<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE article PUBLIC "-//NLM//DTD Journal Publishing DTD v2.3 20070202//EN" "journalpublishing.dtd">
<article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" article-type="research-article" dtd-version="2.3" xml:lang="EN">
<front>
<journal-meta>
<journal-id journal-id-type="publisher-id">Front. Immunol.</journal-id>
<journal-title>Frontiers in Immunology</journal-title>
<abbrev-journal-title abbrev-type="pubmed">Front. Immunol.</abbrev-journal-title>
<issn pub-type="epub">1664-3224</issn>
<publisher>
<publisher-name>Frontiers Media S.A.</publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.3389/fimmu.2025.1513712</article-id>
<article-categories>
<subj-group subj-group-type="heading">
<subject>Immunology</subject>
<subj-group>
<subject>Original Research</subject>
</subj-group>
</subj-group>
</article-categories>
<title-group>
<article-title>The impact of intravenous immunoglobulin therapy on resource utilization associated with viral respiratory tract infections</article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author" corresp="yes">
<name>
<surname>Azar</surname>
<given-names>Antoine</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="author-notes" rid="fn001">
<sup>*</sup>
</xref>
<uri xlink:href="https://loop.frontiersin.org/people/1886328/overview"/>
<role content-type="https://credit.niso.org/contributor-roles/conceptualization/"/>
<role content-type="https://credit.niso.org/contributor-roles/data-curation/"/>
<role content-type="https://credit.niso.org/contributor-roles/formal-analysis/"/>
<role content-type="https://credit.niso.org/contributor-roles/investigation/"/>
<role content-type="https://credit.niso.org/contributor-roles/methodology/"/>
<role content-type="https://credit.niso.org/contributor-roles/resources/"/>
<role content-type="https://credit.niso.org/contributor-roles/supervision/"/>
<role content-type="https://credit.niso.org/contributor-roles/validation/"/>
<role content-type="https://credit.niso.org/contributor-roles/writing-original-draft/"/>
<role content-type="https://credit.niso.org/contributor-roles/writing-review-editing/"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname>Runken</surname>
<given-names>M. Chris</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
<uri xlink:href="https://loop.frontiersin.org/people/1634907/overview"/>
<role content-type="https://credit.niso.org/contributor-roles/conceptualization/"/>
<role content-type="https://credit.niso.org/contributor-roles/data-curation/"/>
<role content-type="https://credit.niso.org/contributor-roles/formal-analysis/"/>
<role content-type="https://credit.niso.org/contributor-roles/investigation/"/>
<role content-type="https://credit.niso.org/contributor-roles/methodology/"/>
<role content-type="https://credit.niso.org/contributor-roles/project-administration/"/>
<role content-type="https://credit.niso.org/contributor-roles/supervision/"/>
<role content-type="https://credit.niso.org/contributor-roles/validation/"/>
<role content-type="https://credit.niso.org/contributor-roles/writing-original-draft/"/>
<role content-type="https://credit.niso.org/contributor-roles/writing-review-editing/"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname>Moughames</surname>
<given-names>Eric</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<role content-type="https://credit.niso.org/contributor-roles/investigation/"/>
<role content-type="https://credit.niso.org/contributor-roles/methodology/"/>
<role content-type="https://credit.niso.org/contributor-roles/resources/"/>
<role content-type="https://credit.niso.org/contributor-roles/writing-original-draft/"/>
<role content-type="https://credit.niso.org/contributor-roles/writing-review-editing/"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname>Howden</surname>
<given-names>Reuben</given-names>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
<uri xlink:href="https://loop.frontiersin.org/people/2963673/overview"/>
<role content-type="https://credit.niso.org/contributor-roles/conceptualization/"/>
<role content-type="https://credit.niso.org/contributor-roles/data-curation/"/>
<role content-type="https://credit.niso.org/contributor-roles/formal-analysis/"/>
<role content-type="https://credit.niso.org/contributor-roles/investigation/"/>
<role content-type="https://credit.niso.org/contributor-roles/methodology/"/>
<role content-type="https://credit.niso.org/contributor-roles/validation/"/>
<role content-type="https://credit.niso.org/contributor-roles/writing-original-draft/"/>
<role content-type="https://credit.niso.org/contributor-roles/writing-review-editing/"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname>Oh</surname>
<given-names>Joshua</given-names>
</name>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
<role content-type="https://credit.niso.org/contributor-roles/conceptualization/"/>
<role content-type="https://credit.niso.org/contributor-roles/data-curation/"/>
<role content-type="https://credit.niso.org/contributor-roles/formal-analysis/"/>
<role content-type="https://credit.niso.org/contributor-roles/investigation/"/>
<role content-type="https://credit.niso.org/contributor-roles/methodology/"/>
<role content-type="https://credit.niso.org/contributor-roles/software/"/>
<role content-type="https://credit.niso.org/contributor-roles/writing-original-draft/"/>
<role content-type="https://credit.niso.org/contributor-roles/writing-review-editing/"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname>Blanchette</surname>
<given-names>Christopher M.</given-names>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
<xref ref-type="aff" rid="aff5">
<sup>5</sup>
</xref>
<uri xlink:href="https://loop.frontiersin.org/people/1287553/overview"/>
<role content-type="https://credit.niso.org/contributor-roles/conceptualization/"/>
<role content-type="https://credit.niso.org/contributor-roles/data-curation/"/>
<role content-type="https://credit.niso.org/contributor-roles/formal-analysis/"/>
<role content-type="https://credit.niso.org/contributor-roles/investigation/"/>
<role content-type="https://credit.niso.org/contributor-roles/methodology/"/>
<role content-type="https://credit.niso.org/contributor-roles/software/"/>
<role content-type="https://credit.niso.org/contributor-roles/supervision/"/>
<role content-type="https://credit.niso.org/contributor-roles/validation/"/>
<role content-type="https://credit.niso.org/contributor-roles/writing-original-draft/"/>
<role content-type="https://credit.niso.org/contributor-roles/writing-review-editing/"/>
</contrib>
</contrib-group>
<aff id="aff1">
<sup>1</sup>
<institution>Division of Allergy and Clinical Immunology, Johns Hopkins University</institution>, <addr-line>Baltimore, MD</addr-line>,&#xa0;<country>United States</country>
</aff>
<aff id="aff2">
<sup>2</sup>
<institution>Global Health Economics Outcomes Research &amp; Real-World Evidence, Grifols Shared Services North America</institution>, <addr-line>Research Triangle Park, NC</addr-line>,&#xa0;<country>United States</country>
</aff>
<aff id="aff3">
<sup>3</sup>
<institution>Department of Applied Physiology, Health &amp; Clinical Sciences, University of North Carolina at Charlotte</institution>, <addr-line>Charlotte, NC</addr-line>,&#xa0;<country>United States</country>
</aff>
<aff id="aff4">
<sup>4</sup>
<institution>Pharmacy Practice and Administration, Rutgers University Ernest Mario School of Pharmacy</institution>, <addr-line>Piscataway, NJ</addr-line>,&#xa0;<country>United States</country>
</aff>
<aff id="aff5">
<sup>5</sup>
<institution>Pharmaceutical &amp; Healthcare Marketing, Saint Joseph&#x2019;s University Erivan Haub School of Business</institution>, <addr-line>Philadelphia, PA</addr-line>,&#xa0;<country>United States</country>
</aff>
<author-notes>
<fn fn-type="edited-by">
<p>Edited by: Pei-Hui Wang, Shandong University, China</p>
</fn>
<fn fn-type="edited-by">
<p>Reviewed by: Xiaosheng Liu, Tsinghua University, China</p>
<p>Haijun Cao, Chinese Academy of Medical Sciences and Peking Union Medical College, China</p>
</fn>
<fn fn-type="corresp" id="fn001">
<p>*Correspondence: Antoine Azar, <email xlink:href="mailto:Antoine.Azar@jhmi.edu">Antoine.Azar@jhmi.edu</email>
</p>
</fn>
</author-notes>
<pub-date pub-type="epub">
<day>06</day>
<month>08</month>
<year>2025</year>
</pub-date>
<pub-date pub-type="collection">
<year>2025</year>
</pub-date>
<volume>16</volume>
<elocation-id>1513712</elocation-id>
<history>
<date date-type="received">
<day>18</day>
<month>10</month>
<year>2024</year>
</date>
<date date-type="accepted">
<day>15</day>
<month>07</month>
<year>2025</year>
</date>
</history>
<permissions>
<copyright-statement>Copyright &#xa9; 2025 Azar, Runken, Moughames, Howden, Oh and Blanchette.</copyright-statement>
<copyright-year>2025</copyright-year>
<copyright-holder>Azar, Runken, Moughames, Howden, Oh and Blanchette</copyright-holder>
<license xlink:href="http://creativecommons.org/licenses/by/4.0/">
<p>This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.</p>
</license>
</permissions>
<abstract>
<sec>
<title>Introduction</title>
<p>Immunocompromised patients with moderate to severe viral respiratory tract infections (VRTIs) may benefit from intravenous immune globulin (IVIG) in combination with antivirals. The impact of this therapy on hospital resource utilization is unknown. The purpose of this study was to assess clinical outcomes and hospital resource utilization associated with IVIG use in immunocompromised patients hospitalized with VRTIs.</p>
</sec>
<sec>
<title>Methods</title>
<p>Using the Premier Healthcare Database, data from 1,927 inpatients with immune deficiency and acute VRTI were analyzed. Outcomes included measures relevant to hospital resource use and patient death rates. Descriptive statistics were used to measure factors associated with IVIG use across the hospital stay. A logistic regression model adjusted for factors associated with the probability of IVIG use within 48 hours of admission. The propensity score was used to weigh subsequent models to assess the length of stay (total and ICU) using a negative binomial model and logistical regression for inpatient death.</p>
</sec>
<sec>
<title>Results</title>
<p>Of the 1,927 patients analyzed, 65 received IVIG. When adjusting for IVIG use within 48 hours of admission and other patient and hospital characteristics, findings showed a significantly shorter hospital length of stay for patients with acute VRTIs when IVIG was given (p = 0.027). The length of ICU stay was also significantly shorter with IVIG use (p = 0.003).</p>
</sec>
<sec>
<title>Discussion</title>
<p>Immunocompromised patients with VRTIs who receive IVIG within 48 hours of ICU admission may have a shorter ICU length of stay and shorter overall hospital length of stay thereby possibly decreasing healthcare resource use.</p>
</sec>
</abstract>
<kwd-group>
<kwd>viral respiratory tract infection</kwd>
<kwd>immune deficiency</kwd>
<kwd>intravenous immune globulin</kwd>
<kwd>healthcare resource utilization</kwd>
<kwd>immunocompromised patients</kwd>
</kwd-group>
<counts>
<fig-count count="1"/>
<table-count count="6"/>
<equation-count count="0"/>
<ref-count count="44"/>
<page-count count="10"/>
<word-count count="3785"/>
</counts>
<custom-meta-wrap>
<custom-meta>
<meta-name>section-in-acceptance</meta-name>
<meta-value>Viral Immunology</meta-value>
</custom-meta>
</custom-meta-wrap>
</article-meta>
</front>
<body>
<sec id="s1" sec-type="intro">
<label>1</label>
<title>Introduction</title>
<p>Severe viral respiratory tract infections (VRTIs) are prevalent in hospital intensive care units and are associated with substantial hospital resource use and treatment costs (<xref ref-type="bibr" rid="B1">1</xref>&#x2013;<xref ref-type="bibr" rid="B3">3</xref>). These infections are predominantly caused by viral pathogens (<xref ref-type="bibr" rid="B4">4</xref>&#x2013;<xref ref-type="bibr" rid="B6">6</xref>). Prior to the emergence of SARS-CoV-2, the most common viral pathogens associated with VRTIs were reported to include rhinovirus, respiratory syncytial virus (RSV), human adenoviruses, parainfluenza virus, influenza virus, and human metapneumovirus (<xref ref-type="bibr" rid="B4">4</xref>, <xref ref-type="bibr" rid="B5">5</xref>, <xref ref-type="bibr" rid="B7">7</xref>).</p>
<p>Immunocompromised patients are particularly vulnerable to VRTIs. Patients receiving immunosuppressive therapy or who have disorders associated with immune deficiency, including patients with a history of cancer, solid organ transplant, bone marrow transplant, and primary immunodeficiency disorders may be at a higher risk of VRTIs, complications of infection, and acute or chronic organ transplant rejection (<xref ref-type="bibr" rid="B5">5</xref>, <xref ref-type="bibr" rid="B7">7</xref>, <xref ref-type="bibr" rid="B8">8</xref>).</p>
<p>The mainstay therapy for VRTI is supportive care. Patients with severe respiratory infections may present with pneumonia, acute respiratory distress syndrome, decompensated heart failure, or exacerbation of underlying chronic lung disease. These conditions may lead to acute hypoxemia and respiratory failure requiring treatment with non-invasive ventilation, oxygen therapy, and/or invasive ventilation, requiring admission to the intensive care unit (ICU). In addition, fluid management is essential to maintain cardiovascular function. Antiviral therapy is often initiated when available to inhibit viral replication (<xref ref-type="bibr" rid="B9">9</xref>).</p>
<p>For immunocompromised patients or other high-risk groups, additional adjuvant therapy with immune-modulating agents, such as corticosteroids, convalescent plasma, or intravenous immune globulin (IVIG), may be considered (<xref ref-type="bibr" rid="B9">9</xref>&#x2013;<xref ref-type="bibr" rid="B12">12</xref>). Beneficial clinical outcomes with the use of antiviral agents in combination with intravenous immune globulin have been described in case reports and small prospective trials (<xref ref-type="bibr" rid="B13">13</xref>&#x2013;<xref ref-type="bibr" rid="B18">18</xref>). Improvement in respiratory function, oxygenation, and chest radiograph appearance have been reported (<xref ref-type="bibr" rid="B14">14</xref>&#x2013;<xref ref-type="bibr" rid="B16">16</xref>), with some trials indicating that antiviral therapy in combination with IVIG may improve survival (<xref ref-type="bibr" rid="B17">17</xref>, <xref ref-type="bibr" rid="B18">18</xref>). Although some studies suggest a potential role for use of IVIG in select patients, the impact of IVIG treatment in VRTI is not fully understood. The objective of this study was to assess clinical outcomes as well as hospital resource utilization associated with IVIG use among immunocompromised patients hospitalized for VRTI.</p>
</sec>
<sec id="s2">
<label>2</label>
<title>Methods</title>
<sec id="s2_1">
<label>2.1</label>
<title>Data source and description</title>
<p>Data from the Premier Perspective Hospital dataset January 1, 2011 to December 31, 2017 were used in this analysis. Premier, Inc. is an alliance of more than 4,000 hospitals and health systems. Premier operates an extensive, detailed clinical and financial database that is populated with hospital data received by Premier in connection with the healthcare operations services provided to hospitals through its informatics products (<xref ref-type="bibr" rid="B19">19</xref>).</p>
<p>The Premier Healthcare Database contains approximately 25% of annual inpatient admissions data in the United States from more than 1,000 hospitals/healthcare systems. The data, from standard hospital discharge files, contains patient demographics and disease state, and information on billed services, including medications, laboratory, diagnostics, and therapeutic services in de-identified daily patient service records. In addition, information on hospital characteristics, including geographic location, bed size, and teaching status, is also available (<xref ref-type="bibr" rid="B19">19</xref>).</p>
<p>All deliverables are de-identified in accordance with HIPAA and therefore the study is exempt from Institutional Review Board review. The time of admission is provided as a month and the time of discharge is provided as a month and year. Day-of-service level details are reported using chronological days (e.g., day 1, day 2) (<xref ref-type="bibr" rid="B19">19</xref>).</p>
</sec>
<sec id="s2_2">
<label>2.2</label>
<title>Study design and measures</title>
<p>For this cross-sectional study design, we used measures occurring within the hospital stay. Hospital data are analyzed at the discharge unit of analysis, not the patient level. A patient may contribute more than one hospitalization to the analysis; however, the measures are limited to the observation within each hospitalization.</p>
<p>The sample included all patient discharges with ICD codes indicating at least one diagnostic code for Acute Viral Respiratory Tract Infection (<xref ref-type="app" rid="app1">Appendix A</xref>) in addition to one diagnostic code for Any Immune Deficiency (<xref ref-type="app" rid="app2">Appendix B</xref>). Discharges were then assigned to treatment groups based on the use of IVIG within the first 48 hours of hospital admission.</p>
<p>Independent variables were identified as patient and hospital characteristics that may confound the relationship between IVIG use and hospital-based outcomes among patients admitted for an acute respiratory viral infection. These patient characteristics included demographics as well as documentation of relevant diseases and treatments indicating diseases that may increase bias association between IVIG use and the outcomes. Hospital characteristics included urban versus rural designation, teaching status, and bed size.</p>
<p>All diagnoses were retrieved at the date of discharge while treatments and procedures were identified on the date of administration. Treatments included antivirals and steroids. Procedures identified were mechanical ventilation, indicating respiratory decompensation, as well as transplantation, which is associated with a compromised immune system. Diagnoses included viral infections and chronic respiratory diseases. Treatments and procedures were measured as binary measures of occurrence. Hospital characteristics were measured to address for clustering of more severe patients in larger hospitals as well as for regional differences. Outcomes included measures relevant to hospital resource use and death. Length of stay, both the total hospital as well as ICU stay were measured in days as a count variable whereas death was measured as a binary variable and measured at discharge.</p>
</sec>
<sec id="s2_3">
<label>2.3</label>
<title>Statistical analysis</title>
<p>All statistical analyses were conducted using SAS version 9.4. All tests were conducted assuming a two-tailed test of significance and alpha level set a-priori at 0.05. Descriptive statistics used Chi-square or Fisher&#x2019;s Exact test and T-tests where appropriate.</p>
<p>To measure the factors associated with IVIG use across the hospitalization, simple bivariate comparisons across the treatment groups were conducted on measures of central tendencies or proportions using appropriate statistical tests. T-tests were used for the comparison of means between cases and controls and Chi-square or Fischer&#x2019;s Exact tests were used for the comparison of proportions between cases and controls.</p>
<p>Due to the imbalance of control cases to viral infection cases, an Inverse Probability Weighting (IPW)-based Regression Model was used where 5,000 controls were randomly drawn. The logistic regression model was developed to adjust for factors associated with the probability of IVIG use within 48 hours of admission. A published study with a very similar patient cohort, showed that IVIG use within 48 hours of hospital admission led to significant changes in outcomes (<xref ref-type="bibr" rid="B20">20</xref>). The propensity score was then used to weight subsequent models to assess the length of stay (total and ICU) using a negative binomial model and logistical regression for inpatient death.</p>
<p>Due to the observational nature of the data used in this study, IPW was used to effectively mimic randomization of treatment. Initially by predicting the probability of a treatment in a regression model using a propensity score given all known covariates. Then, using the inverse of this propensity score for each observation as a weight within the subsequent regression models for each outcome. This method balances baseline covariates evenly across the study population. This method has been described in greater detail elsewhere (<xref ref-type="bibr" rid="B21">21</xref>).</p>
<p>As described in a previous study using similar analyses (<xref ref-type="bibr" rid="B20">20</xref>), propensity score weights were generated using logistic regression with IVIG treatment as the outcome with the following covariates: age, gender, transplant status, baseline respiratory support (supplemental oxygen, ventilator use), antiviral medications, viral organism, immunodeficiency type, and a comorbidity index, which is an additive scale including hypertension, diabetes, heart disease, and renal/urinary tract disease.</p>
<p>The effect of IVIG was evaluated with regard to each of the outcomes using a series of IPW multiple regression analyses. Poisson models were used to evaluate hospital length of stay and ICU length of stay. Logistic regression was used for evaluation of death outcomes. In each model, we controlled for age, gender, transplant status, baseline respiratory support, and antiviral medications. A stratified analysis was performed for patients with specific types of transplants and specific types of viral organisms.</p>
</sec>
</sec>
<sec id="s3" sec-type="results">
<label>3</label>
<title>Results</title>
<sec id="s3_1">
<label>3.1</label>
<title>Patient characteristics</title>
<p>A total of 1,927 inpatients with immune deficiency and acute respiratory viral infections were analyzed (<xref ref-type="fig" rid="f1">
<bold>Figure&#xa0;1</bold>
</xref>). Of those patients, 65 received IVIG during their hospitalization. Patients receiving IVIG were significantly younger in age, more likely to receive ribavirin or other antiviral agents, have a history of primary immune deficiency disorder (PIDD), transplant for bone, lung, or other solid organ transplant, bone marrow transplant, and require intubation during hospitalization compared with patients who did not receive IVIG. Patients who did not receive IVIG were more likely to have cancer or be a recipient of a kidney transplant. (See <xref ref-type="table" rid="T1">
<bold>Table&#xa0;1</bold>
</xref>).</p>
<fig id="f1" position="float">
<label>Figure&#xa0;1</label>
<caption>
<p>A flow chart of patient disposition selecting patients for acute viral respiratory tract infection, immune deficiency and intravenous immunoglobulin (IVIG).</p>
</caption>
<graphic mimetype="image" mime-subtype="tiff" xlink:href="fimmu-16-1513712-g001.tif">
<alt-text content-type="machine-generated">Flowchart detailing a sample selection process. Starting with a total sample of 29,349,676 from January 1, 2011, to December 31, 2017. From these, 1,500,092 cases of acute viral respiratory tract infection are identified. Of these, 1,927 have immune deficiency. Of those, 65 used IVIG, while 1,862 did not.</alt-text>
</graphic>
</fig>
<table-wrap id="T1" position="float">
<label>Table&#xa0;1</label>
<caption>
<p>Patient characteristics of inpatients with any immune deficiency and specific viral respiratory tract infection by IVIG treatment*.</p>
</caption>
<table frame="hsides">
<thead>
<tr>
<th valign="top" align="left">Characteristic</th>
<th valign="top" colspan="2" align="center">Total Patients</th>
<th valign="top" colspan="2" align="center">IVIG Group</th>
<th valign="top" colspan="2" align="center">No IVIG Group</th>
<th valign="top" align="center">
</th>
</tr>
<tr>
<th valign="top" align="left">Total (n, %)</th>
<th valign="top" align="center">1927</th>
<th valign="top" align="center">100.00%</th>
<th valign="top" align="center">65</th>
<th valign="top" align="center">100.00%</th>
<th valign="top" align="center">1862</th>
<th valign="top" align="center">100.00%</th>
<th valign="top" align="center">p-value</th>
</tr>
</thead>
<tbody>
<tr>
<td valign="top" align="left">Age (mean, median, SD)</td>
<td valign="top" colspan="2" align="center">53.88/62/25.61</td>
<td valign="top" colspan="2" align="center">34.83/36/26.83</td>
<td valign="top" colspan="2" align="center">54.54/62/26.36</td>
<td valign="top" align="right">
<bold>&lt;0.0001</bold>
</td>
</tr>
<tr>
<th valign="top" colspan="8" align="left">Sex</th>
</tr>
<tr>
<td valign="top" align="left">&#x2003;Male</td>
<td valign="middle" align="right">922</td>
<td valign="middle" align="right">47.85%</td>
<td valign="middle" align="right">36</td>
<td valign="middle" align="right">55.38%</td>
<td valign="middle" align="right">922</td>
<td valign="middle" align="right">49.52%</td>
<td valign="middle" align="right"/>
</tr>
<tr>
<td valign="top" align="left">&#x2003;Female</td>
<td valign="middle" align="right">940</td>
<td valign="middle" align="right">48.78%</td>
<td valign="middle" align="right">29</td>
<td valign="middle" align="right">44.62%</td>
<td valign="middle" align="right">940</td>
<td valign="middle" align="right">50.48%</td>
<td valign="middle" align="right"/>
</tr>
<tr>
<td valign="top" align="left">Lung Disease</td>
<td valign="middle" align="right">181</td>
<td valign="middle" align="right">9.39%</td>
<td valign="middle" align="right">2</td>
<td valign="middle" align="right">3.08%</td>
<td valign="middle" align="right">179</td>
<td valign="middle" align="right">9.61%</td>
<td valign="middle" align="right">0.0758</td>
</tr>
<tr>
<td valign="top" align="left">Ribavirin</td>
<td valign="middle" align="right">7</td>
<td valign="middle" align="right">0.36%</td>
<td valign="middle" align="right">4</td>
<td valign="middle" align="right">6.15%</td>
<td valign="middle" align="right">3</td>
<td valign="middle" align="right">0.16%</td>
<td valign="middle" align="right">
<bold>&lt;0.0001</bold>
</td>
</tr>
<tr>
<td valign="top" align="left">Antiviral</td>
<td valign="middle" align="right">436</td>
<td valign="middle" align="right">22.63%</td>
<td valign="middle" align="right">26</td>
<td valign="middle" align="right">40.00%</td>
<td valign="middle" align="right">410</td>
<td valign="middle" align="right">22.02%</td>
<td valign="middle" align="right">
<bold>0.0007</bold>
</td>
</tr>
<tr>
<td valign="top" align="left">Prednisone</td>
<td valign="middle" align="right">720</td>
<td valign="middle" align="right">37.36%</td>
<td valign="middle" align="right">26</td>
<td valign="middle" align="right">40.00%</td>
<td valign="middle" align="right">694</td>
<td valign="middle" align="right">37.27%</td>
<td valign="middle" align="right">0.6549</td>
</tr>
<tr>
<td valign="top" align="left">PIDD</td>
<td valign="middle" align="right">266</td>
<td valign="middle" align="right">13.80%</td>
<td valign="middle" align="right">33</td>
<td valign="middle" align="right">50.77%</td>
<td valign="middle" align="right">233</td>
<td valign="middle" align="right">12.51%</td>
<td valign="middle" align="right">
<bold>&lt;0.0001</bold>
</td>
</tr>
<tr>
<td valign="top" align="left">Transplant &#x2013; Other</td>
<td valign="middle" align="right">253</td>
<td valign="middle" align="right">13.13%</td>
<td valign="middle" align="right">14</td>
<td valign="middle" align="right">21.54%</td>
<td valign="middle" align="right">239</td>
<td valign="middle" align="right">12.84%</td>
<td valign="middle" align="right">
<bold>0.0411</bold>
</td>
</tr>
<tr>
<td valign="top" align="left">Transplant &#x2013; Kidney</td>
<td valign="middle" align="right">134</td>
<td valign="middle" align="right">6.95%</td>
<td valign="middle" align="right">0</td>
<td valign="middle" align="right">0.00%</td>
<td valign="middle" align="right">134</td>
<td valign="middle" align="right">7.20%</td>
<td valign="middle" align="right">
<bold>0.0249</bold>
</td>
</tr>
<tr>
<td valign="top" align="left">Transplant &#x2013; Heart</td>
<td valign="middle" align="right">24</td>
<td valign="middle" align="right">1.25%</td>
<td valign="middle" align="right">0</td>
<td valign="middle" align="right">0.00%</td>
<td valign="middle" align="right">24</td>
<td valign="middle" align="right">1.29%</td>
<td valign="middle" align="right">0.357</td>
</tr>
<tr>
<td valign="top" align="left">Transplant &#x2013; Bone</td>
<td valign="middle" align="right">71</td>
<td valign="middle" align="right">3.68%</td>
<td valign="middle" align="right">6</td>
<td valign="middle" align="right">9.23%</td>
<td valign="middle" align="right">65</td>
<td valign="middle" align="right">3.49%</td>
<td valign="middle" align="right">
<bold>0.0157</bold>
</td>
</tr>
<tr>
<td valign="top" align="left">Transplant &#x2013; Lung</td>
<td valign="middle" align="right">20</td>
<td valign="middle" align="right">1.04%</td>
<td valign="middle" align="right">3</td>
<td valign="middle" align="right">4.62%</td>
<td valign="middle" align="right">17</td>
<td valign="middle" align="right">0.91%</td>
<td valign="middle" align="right">
<bold>0.0038</bold>
</td>
</tr>
<tr>
<td valign="top" align="left">Transplant &#x2013; Bone Marrow</td>
<td valign="middle" align="right">12</td>
<td valign="middle" align="right">0.62%</td>
<td valign="middle" align="right">5</td>
<td valign="middle" align="right">7.69%</td>
<td valign="middle" align="right">7</td>
<td valign="middle" align="right">0.38%</td>
<td valign="middle" align="right">
<bold>&lt;0.0001</bold>
</td>
</tr>
<tr>
<td valign="top" align="left">Cancer</td>
<td valign="middle" align="right">1420</td>
<td valign="middle" align="right">73.69%</td>
<td valign="middle" align="right">26</td>
<td valign="middle" align="right">40.00%</td>
<td valign="middle" align="right">1394</td>
<td valign="middle" align="right">74.87%</td>
<td valign="middle" align="right">
<bold>&lt;0.0001</bold>
</td>
</tr>
<tr>
<td valign="top" align="left">Rhinovirus</td>
<td valign="middle" align="right">567</td>
<td valign="middle" align="right">29.42%</td>
<td valign="middle" align="right">19</td>
<td valign="middle" align="right">29.23%</td>
<td valign="middle" align="right">548</td>
<td valign="middle" align="right">29.43%</td>
<td valign="middle" align="right">0.9723</td>
</tr>
<tr>
<td valign="top" align="left">Metapneumovirus</td>
<td valign="middle" align="right">290</td>
<td valign="middle" align="right">15.05%</td>
<td valign="middle" align="right">12</td>
<td valign="middle" align="right">18.46%</td>
<td valign="middle" align="right">278</td>
<td valign="middle" align="right">14.93%</td>
<td valign="middle" align="right">0.4338</td>
</tr>
<tr>
<td valign="top" align="left">RSV</td>
<td valign="middle" align="right">770</td>
<td valign="middle" align="right">39.96%</td>
<td valign="middle" align="right">24</td>
<td valign="middle" align="right">36.92%</td>
<td valign="middle" align="right">746</td>
<td valign="middle" align="right">40.06%</td>
<td valign="middle" align="right">0.6113</td>
</tr>
<tr>
<td valign="top" align="left">Cystic Fibrosis</td>
<td valign="middle" align="right">0</td>
<td valign="middle" align="right">0.00%</td>
<td valign="middle" align="right">0</td>
<td valign="middle" align="right">0.00%</td>
<td valign="middle" align="right">0</td>
<td valign="middle" align="right">0.00%</td>
<td valign="middle" align="right">NA</td>
</tr>
<tr>
<td valign="top" align="left">Intubation</td>
<td valign="middle" align="right">27</td>
<td valign="middle" align="right">1.40%</td>
<td valign="middle" align="right">4</td>
<td valign="middle" align="right">6.15%</td>
<td valign="middle" align="right">23</td>
<td valign="middle" align="right">1.24%</td>
<td valign="middle" align="right">
<bold>0.0009</bold>
</td>
</tr>
<tr>
<td valign="top" align="left">Teaching hospital</td>
<td valign="middle" align="right">1086</td>
<td valign="middle" align="right">56.36%</td>
<td valign="middle" align="right">39</td>
<td valign="middle" align="right">60.00%</td>
<td valign="middle" align="right">1047</td>
<td valign="middle" align="right">56.23%</td>
<td valign="middle" align="right">0.5471</td>
</tr>
</tbody>
</table>
<table-wrap-foot>
<fn>
<p>*Fischer&#x2019;s Exact Test or Chi-Square tests for proportions; t-test for means.</p>
</fn>
<fn>
<p>IVIG, intravenous immunoglobulin; PIDD, primary immune deficiency disorder; RSV, respiratory syncytial virus; SD, standard deviation.</p>
</fn>
<fn>
<p>Values in bold are considered significant (p &lt; 0.05).</p>
</fn>
</table-wrap-foot>
</table-wrap>
<p>Isolated respiratory viruses in the total population were respiratory syncytial virus (39.9%), rhinovirus (29.4%), and metapneumovirus (15.1%). There were no differences in type of virus detected between the two treatment groups (See <xref ref-type="table" rid="T1">
<bold>Table&#xa0;1</bold>
</xref>).</p>
</sec>
<sec id="s3_2">
<label>3.2</label>
<title>Hospital characteristics</title>
<p>No significant differences in hospital characteristics were found between the two treatment groups. The majority of patients were treated in urban teaching hospitals that had a bed capacity of over 400 beds (See <xref ref-type="table" rid="T2">
<bold>Table&#xa0;2</bold>
</xref>).</p>
<table-wrap id="T2" position="float">
<label>Table&#xa0;2</label>
<caption>
<p>Hospital characteristics of inpatients with acute viral respiratory tract infection by IVIG treatment*.</p>
</caption>
<table frame="hsides">
<thead>
<tr>
<th valign="top" align="left">Characteristic</th>
<th valign="top" colspan="2" align="center">Total Patients</th>
<th valign="top" colspan="2" align="center">IVIG Group</th>
<th valign="top" colspan="2" align="center">No IVIG Group</th>
<th valign="top" align="center"/>
</tr>
<tr>
<th valign="top" align="left">Total (n, %)</th>
<th valign="top" align="center">1927</th>
<th valign="top" align="center">100.00%</th>
<th valign="top" align="center">65</th>
<th valign="top" align="center">100.00%</th>
<th valign="top" align="center">1862</th>
<th valign="top" align="center">100.00%</th>
<th valign="top" align="center">p-value</th>
</tr>
</thead>
<tbody>
<tr>
<td valign="top" align="left">Urban</td>
<td valign="top" align="right">1766</td>
<td valign="top" align="right">91.65%</td>
<td valign="top" align="right">62</td>
<td valign="top" align="right">95.38%</td>
<td valign="top" align="right">1704</td>
<td valign="top" align="right">91.51%</td>
<td valign="top" align="right">0.268</td>
</tr>
<tr>
<td valign="top" align="left">Rural</td>
<td valign="top" align="right">161</td>
<td valign="top" align="right">8.35%</td>
<td valign="top" align="right">3</td>
<td valign="top" align="right">4.62%</td>
<td valign="top" align="right">158</td>
<td valign="top" align="right">8.49%</td>
<td valign="top" align="right"/>
</tr>
<tr>
<td valign="top" align="left">Teaching Status</td>
<td valign="top" align="right">1086</td>
<td valign="top" align="right">56.36%</td>
<td valign="top" align="right">39</td>
<td valign="top" align="right">60.00%</td>
<td valign="top" align="right">1047</td>
<td valign="top" align="right">56.23%</td>
<td valign="top" align="right">0.547</td>
</tr>
<tr>
<td valign="top" align="left">Bed Size</td>
<td valign="top" align="right"/>
<td valign="top" align="right"/>
<td valign="top" align="right"/>
<td valign="top" align="right"/>
<td valign="top" align="right"/>
<td valign="top" align="right"/>
<td valign="top" align="right">0.084</td>
</tr>
<tr>
<td valign="top" align="left">&#x2003;0-99</td>
<td valign="top" align="right">54</td>
<td valign="top" align="right">2.8%</td>
<td valign="top" align="right">0</td>
<td valign="top" align="right">0.00%</td>
<td valign="top" align="right">54</td>
<td valign="top" align="right">2.90%</td>
<td valign="top" align="right"/>
</tr>
<tr>
<td valign="top" align="left">&#x2003;100-199</td>
<td valign="top" align="right">235</td>
<td valign="top" align="right">12.20%</td>
<td valign="top" align="right">5</td>
<td valign="top" align="right">7.69%</td>
<td valign="top" align="right">230</td>
<td valign="top" align="right">12.35%</td>
<td valign="top" align="right"/>
</tr>
<tr>
<td valign="top" align="left">&#x2003;200-299</td>
<td valign="top" align="right">222</td>
<td valign="top" align="right">11.52%</td>
<td valign="top" align="right">12</td>
<td valign="top" align="right">18.46%</td>
<td valign="top" align="right">210</td>
<td valign="top" align="right">11.28%</td>
<td valign="top" align="right"/>
</tr>
<tr>
<td valign="top" align="left">&#x2003;300-399</td>
<td valign="top" align="right">264</td>
<td valign="top" align="right">13.70%</td>
<td valign="top" align="right">4</td>
<td valign="top" align="right">6.15%</td>
<td valign="top" align="right">260</td>
<td valign="top" align="right">13.96%</td>
<td valign="top" align="right"/>
</tr>
<tr>
<td valign="top" align="left">&#x2003;400-499</td>
<td valign="top" align="right">194</td>
<td valign="top" align="right">10.07%</td>
<td valign="top" align="right">6</td>
<td valign="top" align="right">9.23%</td>
<td valign="top" align="right">188</td>
<td valign="top" align="right">10.10%</td>
<td valign="top" align="right"/>
</tr>
<tr>
<td valign="top" align="left">&#x2003;500+</td>
<td valign="top" align="right">958</td>
<td valign="top" align="right">49.71%</td>
<td valign="top" align="right">38</td>
<td valign="top" align="right">58.46%</td>
<td valign="top" align="right">920</td>
<td valign="top" align="right">49.41%</td>
<td valign="top" align="right"/>
</tr>
</tbody>
</table>
<table-wrap-foot>
<fn>
<p>*Fischer&#x2019;s Exact Test for proportions.</p>
</fn>
<fn>
<p>IVIG, intravenous immunoglobulin.</p>
</fn>
</table-wrap-foot>
</table-wrap>
</sec>
<sec id="s3_3">
<label>3.3</label>
<title>Healthcare resource use</title>
<p>Without adjustment, there were no significant differences in total hospital length of stay or inpatient death between the two treatment groups. However, patients who received IVIG had a significantly shorter ICU length of stay (mean &#xb1; SD). The mean length of stay in the ICU for patients who received IVIG was 1.63 &#xb1; 3.59 days compared with 3.40 &#xb1; 7.71 days for those patients who did not receive IVIG (p &lt;0.0001) resulting in a 50% reduction in ICU length of stay. (See <xref ref-type="table" rid="T3">
<bold>Table&#xa0;3</bold>
</xref>).</p>
<table-wrap id="T3" position="float">
<label>Table&#xa0;3</label>
<caption>
<p>Healthcare resource use associated with IVIG treatment among inpatients with any immune deficiency and acute viral respiratory tract infection*.</p>
</caption>
<table frame="hsides">
<thead>
<tr>
<th valign="top" align="left">Characteristic</th>
<th valign="top" colspan="3" align="center">Total Patients</th>
<th valign="top" colspan="2" align="center">IVIG Group</th>
<th valign="top" colspan="3" align="center">No IVIG Group</th>
<th valign="top" align="center"/>
</tr>
<tr>
<th valign="top" align="left">Total (n, %)</th>
<th valign="top" colspan="2" align="center">1927</th>
<th valign="top" align="center">100.00%</th>
<th valign="top" align="center">65</th>
<th valign="top" align="center">100.00%</th>
<th valign="top" colspan="2" align="center">1862</th>
<th valign="top" align="center">100.00%</th>
<th valign="top" align="center">p-value</th>
</tr>
</thead>
<tbody>
<tr>
<td valign="top" align="left">Length of hospital stay in days (mean/median/SD)</td>
<td valign="top" colspan="3" align="center">10.90/7/13.46</td>
<td valign="top" colspan="2" align="center">10.86/7/12.96</td>
<td valign="top" colspan="3" align="center">12.15/6/23.69</td>
<td valign="top" align="right">0.662</td>
</tr>
<tr>
<td valign="top" align="left">Length of ICU stay in days (mean/median/SD)</td>
<td valign="top" colspan="3" align="center">3.34/0/7.62</td>
<td valign="top" colspan="2" align="center">1.63/0/3.59</td>
<td valign="top" colspan="3" align="center">3.40/0/7.71</td>
<td valign="top" align="right">&lt;0.0001</td>
</tr>
<tr>
<td valign="top" align="left">ICU stay</td>
<td valign="top" colspan="2" align="center">881</td>
<td valign="top" align="center">45.72%</td>
<td valign="top" align="center">20</td>
<td valign="top" align="center">30.77%</td>
<td valign="top" colspan="2" align="center">861</td>
<td valign="top" align="center">46.24%</td>
<td valign="top" align="right">&lt;0.0001</td>
</tr>
<tr>
<td valign="top" align="left">Inpatient death</td>
<td valign="top" colspan="2" align="center">176</td>
<td valign="top" align="center">9.13%</td>
<td valign="top" align="center">4</td>
<td valign="top" align="center">6.15%</td>
<td valign="top" colspan="2" align="center">172</td>
<td valign="top" align="center">8.93%</td>
<td valign="top" align="center">0.514</td>
</tr>
</tbody>
</table>
<table-wrap-foot>
<fn>
<p>*Fischer&#x2019;s Exact Test for proportions; t-test for means.</p>
</fn>
<fn>
<p>ICU, intensive care unit; IVIG, intravenous immunoglobulin; SD, standard deviation.</p>
</fn>
</table-wrap-foot>
</table-wrap>
<p>When adjusting for IVIG use within 48 hours of admission as well as immune system complications, hospital characteristics, relative concomitant medications, and demographics we find that IVIG reduces utilization. The adjustment now revealed a significantly shorter length of hospital stay when patients with VRTI were given IVIG (-3.24; 95% CI, -6.11 to -0.37; p = 0.027). The length of ICU stay was significantly shorter with IVIG use (-1.83; 95% CI, -3.04 to -0.62; p = 0.003). However, no difference was seen with inpatient death rates (See <xref ref-type="table" rid="T4">
<bold>Table&#xa0;4</bold>
</xref>).</p>
<table-wrap id="T4" position="float">
<label>Table&#xa0;4</label>
<caption>
<p>Adjusted outcomes IVIG vs. No IVIG.</p>
</caption>
<table frame="hsides">
<thead>
<tr>
<th valign="top" align="left">Measure</th>
<th valign="top" align="center">Coefficient</th>
<th valign="top" colspan="2" align="center">95% CI</th>
<th valign="top" align="center">p-value</th>
</tr>
</thead>
<tbody>
<tr>
<td valign="top" align="left">Length of hospital stay in days*</td>
<td valign="top" align="right">-3.24</td>
<td valign="top" align="right">-6.11</td>
<td valign="top" align="right">-0.37</td>
<td valign="top" align="right">0.027</td>
</tr>
<tr>
<td valign="top" align="left">Length of ICU stay in days*</td>
<td valign="top" align="right">-1.83</td>
<td valign="top" align="right">-3.04</td>
<td valign="top" align="right">-0.62</td>
<td valign="top" align="right">0.003</td>
</tr>
<tr>
<td valign="top" align="left">Inpatient death<sup>+</sup>
</td>
<td valign="top" align="right">1.08</td>
<td valign="top" align="right">0.33</td>
<td valign="top" align="right">3.54</td>
<td valign="top" align="right">0.903</td>
</tr>
</tbody>
</table>
<table-wrap-foot>
<fn>
<p>*Adjustment for immune type (transplant, cancer), RSV, PIDD, age, prednisone, antiviral, ribavirin, urban, teaching, intubation, lung disease using inverse probability weighted regression.</p>
</fn>
<fn>
<p>+Adjustment for immune type (transplant, cancer), RSV, PIDD, age, prednisone, antiviral, ribavirin, urban, intubation, lung disease using logistic regression.</p>
</fn>
<fn>
<p>CI, confidence interval; ICU, intensive care unit; IVIG, intravenous immunoglobulin; PIDD, primary immune deficiency disorder; RSV, respiratory syncytial virus.</p>
</fn>
</table-wrap-foot>
</table-wrap>
</sec>
</sec>
<sec id="s4" sec-type="discussion">
<label>4</label>
<title>Discussion</title>
<p>Over 70 years ago, the use of gamma globulin to successfully reduce the frequency of serious bacterial infections was first reported (<xref ref-type="bibr" rid="B22">22</xref>). However, there are still limited data on the impact of IVIG use in specific clinical situations. The effects of IVIG administration have been studied as a treatment in RSV, respiratory infections following chemotherapy and hematopoietic transplantation, and the combination of aerosolized ribavirin and IVIG, demonstrating its efficacy in a range of clinical situations (<xref ref-type="bibr" rid="B17">17</xref>, <xref ref-type="bibr" rid="B23">23</xref>&#x2013;<xref ref-type="bibr" rid="B25">25</xref>).</p>
<p>The impact of IVIG therapy on hospital length of stay may vary depending on the specific patient population and the condition being treated. Moreover, patient comorbidities and disease severity may play a role in determining outcomes like hospital length of stay. Little is known about IVIG treatment of immunocompromised patients who are hospitalized for VRTI. In this study immunocompromised patients hospitalized with VRTIs, who received IVIG within the first 48 hours of admission, had a shorter length of stay in the ICU and a shorter overall hospital length of stay, which could lead to improved clinical outcomes and significant cost savings. A shorter length of stay following IVIG treatment has also been reported in COVID-19 patients in a prospective randomized trial and in a meta-analysis of critically ill COVID-19 patients (<xref ref-type="bibr" rid="B26">26</xref>, <xref ref-type="bibr" rid="B27">27</xref>). Conversely, in other meta-analyses of COVID-19 patients, IVIG demonstrated no benefit with regard to patient outcomes and hospital length of stay or even an increase in hospital length of stay (<xref ref-type="bibr" rid="B28">28</xref>, <xref ref-type="bibr" rid="B29">29</xref>). The inconsistency in the literature with regard to the efficacy of IVIG treatment in influencing length of stay in COVID-19 patients may be related to how recent COVID-19 became a major public health problem and more research is needed to improve clarity.</p>
<p>Patients with an RSV infection made up almost 40% of our sample. Previous studies on the efficacy of IVIG treatment in RSV patients focused on pediatric populations and although outcomes were improved, hospital length of stay was not shorter a result supported in a recent Cochrane Systematic review (<xref ref-type="bibr" rid="B23">23</xref>, <xref ref-type="bibr" rid="B30">30</xref>, <xref ref-type="bibr" rid="B31">31</xref>). In the present study, patients treated with IVIG were adults and therefore the combination of these studies suggests that IVIG treatment can be efficacious in a broad age range, but this may vary depending on the specifics of patient populations. Reduced hospital length of stay with IVIG treatment has also been reported in relation to other conditions. For example, when patients with Guillain-Barr&#xe9; Syndrome were treated with IVIG, mechanical ventilation weaning was improved, and hospital length of stay was significantly shorter compared to patients treated with plasma exchange (<xref ref-type="bibr" rid="B32">32</xref>, <xref ref-type="bibr" rid="B33">33</xref>). This suggests that IVIG treatment may be beneficial in a range of infection types.</p>
<p>In this study, patients who were treated with IVIG were more likely to have had a transplant of some kind. Use of IVIG desensitization in renal transplant recipients was associated with a significantly improved survival (<xref ref-type="bibr" rid="B34">34</xref>, <xref ref-type="bibr" rid="B35">35</xref>). Moreover, IVIG treatment in liver transplant patients may also reduce organ rejection, which is important considering the limited availability of viable organs (<xref ref-type="bibr" rid="B36">36</xref>, <xref ref-type="bibr" rid="B37">37</xref>). Improved transplant patient survival and reduced organ rejection rates could be considered a proxy for the amount of time a patient spends in the hospital and therefore we provide further evidence to support this notion.</p>
<p>One interesting outcome of this study was that IVIG treatment reduced hospital length of stay without improving mortality rates, which does not align with previous analyses. However, while speculative, this result may be biased since patients with more severe illness were more likely to be treated with IVIG. Conversely, in a recent meta-analysis, mortality in streptococcal toxic shock syndrome patients treated with clindamycin and IVIG (vs. clindamycin only) reduced by more than half (<xref ref-type="bibr" rid="B38">38</xref>). Further, in severely ill COVID-19 patients, high dose IVIG reduced mortality rates (<xref ref-type="bibr" rid="B39">39</xref>). Overall, evidence suggests that IVIG treatment may be associated with a lower risk of mortality in some clinical settings. However, the effect of IVIG may depend on the underlying condition, the indication for treatment, and the individual patient as suggested by the differences in the result of this study compared to previous works.</p>
<p>A primary focus of this study was the use of IVIG in patients with VRTIs, for which data is lacking. Interest in the use of IVIG in the treatment of VRTI is based on the recognition of the immunomodulatory effects of high-dose IVIG therapy. The proposed mechanisms of immunomodulation are mediated by the two functional domains of IgG: the F(ab)&#x2019;2 fragment that is responsible for specific antigen binding and the Fc fragment that is responsible for Fc receptor and complement binding. F(ab)&#x2019;2-mediated mechanisms of immunomodulation include passive immunity through the neutralization of pathogenic antigens and an anti-inflammatory effect through neutralization of pro-inflammatory cytokines and chemokines. Fc-mediated anti-inflammatory effects are thought to result from the saturation of Fc receptors (Fc&#x3b3;Rs) and upregulation of the inhibitory Fc receptor (Fc&#x3b3;RIIB) (<xref ref-type="bibr" rid="B40">40</xref>). Viral respiratory tract infections have been associated with excessive production of pro-inflammatory cytokines, which can mediate damage to normal tissue in the lungs and other organs. In these hyper-immune conditions, high-dose IVIG may play an important role in immune modulation (<xref ref-type="bibr" rid="B40">40</xref>).</p>
<p>Based on the proposed mechanisms of action, high-dose IVIG has been used clinically in the treatment of VRTI. Although the most effective timing of therapy is unclear, some studies suggest that early initiation of immune modulators (corticosteroids or IVIG) in addition to antivirals may provide clinical benefit (<xref ref-type="bibr" rid="B41">41</xref>, <xref ref-type="bibr" rid="B42">42</xref>).</p>
<p>While there is no definitive evidence from randomized clinical&#xa0;trials to support the use of IVIG in the treatment of VRTI, several open-label studies describe the potential benefits of high-dose IVIG therapy in combination with antiviral agents in immunocompromised patients who are at high risk for VRTI. Studies suggest that early treatment of upper respiratory RSV infection with aerosolized ribavirin and IVIG may reduce the frequency of progression to pneumonia and death in adult transplant recipients (<xref ref-type="bibr" rid="B17">17</xref>, <xref ref-type="bibr" rid="B18">18</xref>). Similarly, studies examining outcomes in bone marrow transplant patients with respiratory CMV infection found that treatment with ganciclovir and IVIG was associated with clinical improvement and survival (<xref ref-type="bibr" rid="B43">43</xref>, <xref ref-type="bibr" rid="B44">44</xref>).</p>
<p>The examination of healthcare resource utilization, as described in this study, provides additional data to evaluate the impact of IVIG therapy in the setting of VRTI. The reduction in ICU length of stay and overall hospital length of stay suggests beneficial resource utilization outcomes with IVIG therapy that may indirectly reflect positive clinical outcomes for immunocompromised patients with VRTI.</p>
<p>There are potential limitations in this study. Hospital chargemaster data have the potential for errors and miscoding, which could introduce misclassification bias into the study by incorrectly identifying patients with IVIG treatment. Patients may be duplicated as the data are cross-sectional and each occurrence represents a discharge, not a patient. Therefore, patients having multiple hospitalizations may be occurring in the study analysis as separate discharges. And finally, the dosage of IVIG is not available in the dataset, so it is unknown whether a patient received high-dose or low-dose IVIG and how that might have affected the outcomes.</p>
<p>In summary, immunocompromised patients with VRTI who receive IVIG within 48 hours of ICU admission may have a shorter ICU length of stay and shorter overall hospital length of stay. These findings suggest possible beneficial health outcomes for the patient as well as for hospital resource utilization. Further research via prospective clinical trials is needed to explore the potential impact of IVIG in this setting on other health outcomes and resource use to identify specific patients who may benefit from IVIG therapy as part of their treatment for viral respiratory tract infection.</p>
</sec>
</body>
<back>
<sec id="s5" sec-type="data-availability">
<title>Data availability statement</title>
<p>The data supporting the conclusions of this article is available&#xa0;from the Premier Healthcare Database. Information on the Premier database is available at: <ext-link ext-link-type="uri" xlink:href="https://offers.premierinc.com/rs/381-NBB-525/images/PremierHealthcareDatabaseWhitepaper.pdf">PremierHealthcareDatabaseWhitepaper.pdf (premierinc.com)</ext-link>.</p>
</sec>
<sec id="s6" sec-type="ethics-statement">
<title>Ethics statement</title>
<p>Ethical approval was not required for the study involving humans in accordance with the local legislation and institutional requirements. Written informed consent to participate in this study was not required from the participants or the participants&#x2019; legal guardians/next of kin in accordance with the national legislation and the institutional requirements.</p>
</sec>
<sec id="s7" sec-type="author-contributions">
<title>Author contributions</title>
<p>AA: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Resources, Supervision, Validation, Writing &#x2013; original draft, Writing &#x2013; review &amp; editing. MCR: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Supervision, Validation, Writing &#x2013; original draft, Writing &#x2013; review &amp; editing. EM: Investigation, Methodology, Resources, Writing &#x2013; original draft, Writing &#x2013; review &amp; editing. RH: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Validation, Writing &#x2013; original draft, Writing &#x2013; review &amp; editing. JO: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Software, Writing &#x2013; original draft, Writing &#x2013; review &amp; editing. CB: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Software, Supervision, Validation, Writing &#x2013; original draft, Writing &#x2013; review &amp; editing.</p>
</sec>
<sec id="s8" sec-type="funding-information">
<title>Funding</title>
<p>The author(s) declare that financial support was received for the research and/or publication of this article.</p>
</sec>
<ack>
<title>Acknowledgments</title>
<p>Dori Greene, RN, MS provided medical writing assistance under the direction of the authors.</p>
</ack>
<sec id="s9" sec-type="COI-statement">
<title>Conflict of interest</title>
<p>MCR is a full-time employee of Grifols.</p>
<p>The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.</p>
<p>The authors declare that this study received funding from Grifols. The funder was involved in the study design, analysis, data interpretation, writing of this article, as well as the decision to submit it for publication.</p>
<p>The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision.</p>
</sec>
<sec id="s10" sec-type="ai-statement">
<title>Generative AI statement</title>
<p>The author(s) declare that no Generative AI was used in the creation of this manuscript.</p>
</sec>
<sec id="s11" sec-type="disclaimer">
<title>Publisher&#x2019;s note</title>
<p>All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.</p>
</sec>
<ref-list>
<title>References</title>
<ref id="B1">
<label>1</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Vincent</surname> <given-names>JL</given-names>
</name>
<name>
<surname>Rello</surname> <given-names>J</given-names>
</name>
<name>
<surname>Marshall</surname> <given-names>J</given-names>
</name>
<name>
<surname>Silva</surname> <given-names>E</given-names>
</name>
<name>
<surname>Anzueto</surname> <given-names>A</given-names>
</name>
<name>
<surname>Martin</surname> <given-names>CD</given-names>
</name>
<etal/>
</person-group>. <article-title>International study of the prevalence and outcomes of infection in intensive care units</article-title>. <source>JAMA</source>. (<year>2009</year>) <volume>302</volume>:<page-range>2323&#x2013;9</page-range>. doi:&#xa0;<pub-id pub-id-type="doi">10.1001/jama.2009.1754</pub-id>, PMID: <pub-id pub-id-type="pmid">19952319</pub-id></citation></ref>
<ref id="B2">
<label>2</label>
<citation citation-type="web">
<person-group person-group-type="author">
<name>
<surname>Pfuntner</surname> <given-names>A</given-names>
</name>
<name>
<surname>Wier</surname> <given-names>LM</given-names>
</name>
<name>
<surname>Steiner</surname> <given-names>C</given-names>
</name>
</person-group>. <article-title>Costs for hospital stays in the United States</article-title>. In: <source>HCUP Statistical Brief 168</source>. <publisher-name>Agency for Healthcare Research and Quality</publisher-name>, <publisher-loc>Rockville, MD</publisher-loc> (<year>2011</year>). Available online at: <uri xlink:href="https://hcup-us.ahrq.gov/reports/statbriefs/sb168-Hospital-Costs-United-States-2011.pdf">https://hcup-us.ahrq.gov/reports/statbriefs/sb168-Hospital-Costs-United-States-2011.pdf</uri>.</citation></ref>
<ref id="B3">
<label>3</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Amand</surname> <given-names>C</given-names>
</name>
<name>
<surname>Tong</surname> <given-names>S</given-names>
</name>
<name>
<surname>Kieffer</surname> <given-names>A</given-names>
</name>
<name>
<surname>Kyaw</surname> <given-names>MH</given-names>
</name>
</person-group>. <article-title>Healthcare resource use and economic&#xa0;burden attributable to respiratory syncytial virus in the United States: a claims database analysis</article-title>. <source>BMC Health Serv Res</source>. (<year>2018</year>) <volume>18</volume>:<fpage>294</fpage>&#x2013;<lpage>308</lpage>. doi:&#xa0;<pub-id pub-id-type="doi">10.1186/s12913-018-3066-1</pub-id>, PMID: <pub-id pub-id-type="pmid">29678177</pub-id></citation></ref>
<ref id="B4">
<label>4</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Jain</surname> <given-names>S</given-names>
</name>
<name>
<surname>Self</surname> <given-names>WH</given-names>
</name>
<name>
<surname>Wunderink</surname> <given-names>RG</given-names>
</name>
<name>
<surname>Fakhran</surname> <given-names>S</given-names>
</name>
<name>
<surname>Balk</surname> <given-names>R</given-names>
</name>
<name>
<surname>Bramley</surname> <given-names>AM</given-names>
</name>
<etal/>
</person-group>. <article-title>Community-acquired pneumonia requiring hospitalization among U.S. adults</article-title>. <source>New Engl J Med</source>. (<year>2015</year>) <volume>373</volume>:<page-range>415&#x2013;27</page-range>. doi:&#xa0;<pub-id pub-id-type="doi">10.1056/NEJMoa1500245</pub-id>, PMID: <pub-id pub-id-type="pmid">26172429</pub-id></citation></ref>
<ref id="B5">
<label>5</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Hong</surname> <given-names>HL</given-names>
</name>
<name>
<surname>Hong</surname> <given-names>SB</given-names>
</name>
<name>
<surname>Ko</surname> <given-names>GB</given-names>
</name>
<name>
<surname>Huh</surname> <given-names>JW</given-names>
</name>
<name>
<surname>Sung</surname> <given-names>H</given-names>
</name>
<name>
<surname>Do</surname> <given-names>KH</given-names>
</name>
<etal/>
</person-group>. <article-title>Viral infection is not uncommon in adult patients with severe hospital-acquired pneumonia</article-title>. <source>PloS One</source>. (<year>2014</year>) <volume>9</volume>:<elocation-id>e95865</elocation-id>. doi:&#xa0;<pub-id pub-id-type="doi">10.1371/journal.pone.0095865</pub-id>, PMID: <pub-id pub-id-type="pmid">24752070</pub-id></citation></ref>
<ref id="B6">
<label>6</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Shorr</surname> <given-names>AF</given-names>
</name>
<name>
<surname>Zilberberg</surname> <given-names>MD</given-names>
</name>
<name>
<surname>Micek</surname> <given-names>ST</given-names>
</name>
<name>
<surname>Kollef</surname> <given-names>MH</given-names>
</name>
</person-group>. <article-title>Viruses are prevalent in non-ventilated hospital-acquired pneumonia</article-title>. <source>Respir Med</source>. (<year>2017</year>) <volume>122</volume>:<fpage>76</fpage>&#x2013;<lpage>80</lpage>. doi:&#xa0;<pub-id pub-id-type="doi">10.1016/j.rmed.2016.11.023</pub-id>, PMID: <pub-id pub-id-type="pmid">27993295</pub-id></citation></ref>
<ref id="B7">
<label>7</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Vilchez</surname> <given-names>RA</given-names>
</name>
<name>
<surname>McCurry</surname> <given-names>K</given-names>
</name>
<name>
<surname>Dauber</surname> <given-names>J</given-names>
</name>
<name>
<surname>Iacono</surname> <given-names>A</given-names>
</name>
<name>
<surname>Griffith</surname> <given-names>B</given-names>
</name>
<name>
<surname>Fung</surname> <given-names>J</given-names>
</name>
<etal/>
</person-group>. <article-title>Influenza virus infection in adult solid organ transplant recipients</article-title>. <source>Am J Transplant</source>. (<year>2002</year>) <volume>2</volume>:<page-range>287&#x2013;91</page-range>. doi:&#xa0;<pub-id pub-id-type="doi">10.1034/j.1600-6143.2002.20315.x</pub-id>, PMID: <pub-id pub-id-type="pmid">12096793</pub-id></citation></ref>
<ref id="B8">
<label>8</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Gaunt</surname> <given-names>ER</given-names>
</name>
<name>
<surname>Harvala</surname> <given-names>H</given-names>
</name>
<name>
<surname>McIntyre</surname> <given-names>C</given-names>
</name>
<name>
<surname>Templeton</surname> <given-names>KE</given-names>
</name>
<name>
<surname>Simmonds</surname> <given-names>P</given-names>
</name>
</person-group>. <article-title>Disease burden of the most commonly detected viruses in hospitalized patients calculated using the disability adjusted life year (DALY) model</article-title>. <source>J Clin Virol</source>. (<year>2011</year>) <volume>52</volume>:<page-range>215&#x2013;21</page-range>. doi:&#xa0;<pub-id pub-id-type="doi">10.1016/j.jcv.2011.07.017</pub-id>, PMID: <pub-id pub-id-type="pmid">21880543</pub-id></citation></ref>
<ref id="B9">
<label>9</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Arabi</surname> <given-names>YM</given-names>
</name>
<name>
<surname>Fowler</surname> <given-names>R</given-names>
</name>
<name>
<surname>Hayden</surname> <given-names>FG</given-names>
</name>
</person-group>. <article-title>Critical care management of adults with community-acquired severe respiratory viral infection</article-title>. <source>Intensive Care Med</source>. (<year>2020</year>) <volume>46</volume>:<page-range>315&#x2013;28</page-range>. doi:&#xa0;<pub-id pub-id-type="doi">10.1007/s00134-020-05943-5</pub-id>, PMID: <pub-id pub-id-type="pmid">32040667</pub-id></citation></ref>
<ref id="B10">
<label>10</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Walter</surname> <given-names>JM</given-names>
</name>
<name>
<surname>Wunderink</surname> <given-names>RG</given-names>
</name>
</person-group>. <article-title>Severe respiratory viral infections</article-title>. <source>Infect Dis Clin N Am</source>. (<year>2017</year>) <volume>31</volume>:<page-range>455&#x2013;74</page-range>. doi:&#xa0;<pub-id pub-id-type="doi">10.1016/j.idc.2017.05.004</pub-id>, PMID: <pub-id pub-id-type="pmid">28687214</pub-id></citation></ref>
<ref id="B11">
<label>11</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Lai</surname> <given-names>ST</given-names>
</name>
</person-group>. <article-title>Treatment of severe acute respiratory syndrome</article-title>. <source>Eur J Clin Microbiol Infect Dis</source>. (<year>2005</year>) <volume>24</volume>:<page-range>583&#x2013;91</page-range>. doi:&#xa0;<pub-id pub-id-type="doi">10.1007/s10096-005-0004-z</pub-id>, PMID: <pub-id pub-id-type="pmid">16172857</pub-id></citation></ref>
<ref id="B12">
<label>12</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Donovan</surname> <given-names>S</given-names>
</name>
<name>
<surname>Bearman</surname> <given-names>GML</given-names>
</name>
</person-group>. <article-title>Use of intravenous immunoglobulin in critically ill patients</article-title>. <source>Curr Infect Dis Rep</source>. (<year>2014</year>) <volume>16</volume>:<page-range>447&#x2013;54</page-range>. doi:&#xa0;<pub-id pub-id-type="doi">10.1007/s11908-014-0447-4</pub-id>, PMID: <pub-id pub-id-type="pmid">25388018</pub-id></citation></ref>
<ref id="B13">
<label>13</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Perez</surname> <given-names>EE</given-names>
</name>
<name>
<surname>Orange</surname> <given-names>JS</given-names>
</name>
<name>
<surname>Bonilla</surname> <given-names>F</given-names>
</name>
<name>
<surname>Chinen</surname> <given-names>J</given-names>
</name>
<name>
<surname>Chinn</surname> <given-names>IK</given-names>
</name>
<name>
<surname>Dorsey</surname> <given-names>M</given-names>
</name>
<etal/>
</person-group>. <article-title>Update on the use of immunoglobulin in human disease: a review of evidence</article-title>. <source>J Allergy Clin Immunol</source>. (<year>2017</year>) <volume>139</volume>:<fpage>S1</fpage>&#x2013;<lpage>S46</lpage>. doi:&#xa0;<pub-id pub-id-type="doi">10.1016/j.jaci.2016.09.023</pub-id>, PMID: <pub-id pub-id-type="pmid">28041678</pub-id></citation></ref>
<ref id="B14">
<label>14</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Sabroe</surname> <given-names>I</given-names>
</name>
<name>
<surname>McHale</surname> <given-names>J</given-names>
</name>
<name>
<surname>Tait</surname> <given-names>DR</given-names>
</name>
<name>
<surname>Lynn</surname> <given-names>WA</given-names>
</name>
<name>
<surname>Ward</surname> <given-names>KN</given-names>
</name>
<name>
<surname>Shaunak</surname> <given-names>S</given-names>
</name>
</person-group>. <article-title>Treatment of adenoviral pneumonitis with intravenous ribavirin and immunoglobulin</article-title>. <source>Thorax</source>. (<year>1995</year>) <volume>50</volume>:<page-range>1219&#x2013;20</page-range>. doi:&#xa0;<pub-id pub-id-type="doi">10.1136/thx.50.11.1219</pub-id>, PMID: <pub-id pub-id-type="pmid">8553282</pub-id></citation></ref>
<ref id="B15">
<label>15</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Shahda</surname> <given-names>S</given-names>
</name>
<name>
<surname>Carlos</surname> <given-names>WG</given-names>
</name>
<name>
<surname>Kiel</surname> <given-names>PJ</given-names>
</name>
<name>
<surname>Khan</surname> <given-names>BA</given-names>
</name>
<name>
<surname>Hage</surname> <given-names>CA</given-names>
</name>
</person-group>. <article-title>The human metapneumovirus: a case series and review of the literature</article-title>. <source>Transpl Infect Dis</source>. (<year>2011</year>) <volume>13</volume>:<page-range>324&#x2013;8</page-range>. doi:&#xa0;<pub-id pub-id-type="doi">10.1111/j.1399-3062.2010.00575.x</pub-id>, PMID: <pub-id pub-id-type="pmid">21631655</pub-id></citation></ref>
<ref id="B16">
<label>16</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Crooks</surname> <given-names>BN</given-names>
</name>
<name>
<surname>Taylor</surname> <given-names>CE</given-names>
</name>
<name>
<surname>Turner</surname> <given-names>AJ</given-names>
</name>
<name>
<surname>Osman</surname> <given-names>HK</given-names>
</name>
<name>
<surname>Abinun</surname> <given-names>M</given-names>
</name>
<name>
<surname>Flood</surname> <given-names>TJ</given-names>
</name>
<etal/>
</person-group>. <article-title>Respiratory viral infections in primary immune deficiencies: significance and relevance to clinical outcome in a single BMT unit</article-title>. <source>Bone Marrow Transplant</source>. (<year>2000</year>) <volume>26</volume>:<page-range>1097&#x2013;102</page-range>. doi:&#xa0;<pub-id pub-id-type="doi">10.1038/sj.bmt.1702656</pub-id>, PMID: <pub-id pub-id-type="pmid">11108309</pub-id></citation></ref>
<ref id="B17">
<label>17</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Ghosh</surname> <given-names>S</given-names>
</name>
<name>
<surname>Champlin</surname> <given-names>RE</given-names>
</name>
<name>
<surname>Englund</surname> <given-names>J</given-names>
</name>
<name>
<surname>Giralt</surname> <given-names>SA</given-names>
</name>
<name>
<surname>Rolston</surname> <given-names>K</given-names>
</name>
<name>
<surname>Raad</surname> <given-names>I</given-names>
</name>
<etal/>
</person-group>. <article-title>Respiratory syncytial virus upper respiratory tract illnesses in adult blood and marrow transplant recipients: combination therapy with aerosolized ribavirin and intravenous immunoglobulin</article-title>. <source>Bone Marrow Transplant</source>. (<year>2000</year>) <volume>25</volume>:<page-range>751&#x2013;5</page-range>. doi:&#xa0;<pub-id pub-id-type="doi">10.1038/sj.bmt.1702228</pub-id>, PMID: <pub-id pub-id-type="pmid">10745261</pub-id></citation></ref>
<ref id="B18">
<label>18</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Whimbey</surname> <given-names>E</given-names>
</name>
<name>
<surname>Champlin</surname> <given-names>RE</given-names>
</name>
<name>
<surname>Englund</surname> <given-names>JA</given-names>
</name>
<name>
<surname>Mirza</surname> <given-names>NQ</given-names>
</name>
<name>
<surname>Piedra</surname> <given-names>PA</given-names>
</name>
<name>
<surname>Goodrich</surname> <given-names>JM</given-names>
</name>
<etal/>
</person-group>. <article-title>Combination therapy with aerosolized ribavirin and intravenous immunoglobulin for respiratory syncytial virus disease in adult bone marrow transplant recipients</article-title>. <source>Bone Marrow Transplant</source>. (<year>1995</year>) <volume>16</volume>:<page-range>393&#x2013;9</page-range>.</citation></ref>
<ref id="B19">
<label>19</label>
<citation citation-type="web">
<article-title>Premier Healthcare Database White Paper: Data that informs and performs, March 2, 2020</article-title>. <publisher-name>Premier, Inc</publisher-name>. Available online at: <uri xlink:href="https://learn.premierinc.com/white-papers/premier-healthcare-database-whitepaper">https://learn.premierinc.com/white-papers/premier-healthcare-database-whitepaper</uri>.</citation></ref>
<ref id="B20">
<label>20</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Moughames</surname> <given-names>E</given-names>
</name>
<name>
<surname>Sakayan</surname> <given-names>S</given-names>
</name>
<name>
<surname>Prichett</surname> <given-names>L</given-names>
</name>
<name>
<surname>Runken</surname> <given-names>MC</given-names>
</name>
<name>
<surname>Borst</surname> <given-names>D</given-names>
</name>
<name>
<surname>Tversky</surname> <given-names>J</given-names>
</name>
<etal/>
</person-group>. <article-title>Outcomes of intravenous immunoglobulin treatment of immunocompromised patients with viral respiratory infections</article-title>. <source>Ann Allergy Asthma Immunol</source>. (<year>2025</year>) <volume>134</volume>:<fpage>85</fpage>&#x2013;<lpage>90 e1</lpage>. doi:&#xa0;<pub-id pub-id-type="doi">10.1016/j.anai.2024.09.001</pub-id>, PMID: <pub-id pub-id-type="pmid">39251021</pub-id></citation></ref>
<ref id="B21">
<label>21</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Chesnaye</surname> <given-names>NC</given-names>
</name>
<name>
<surname>Stel</surname> <given-names>VS</given-names>
</name>
<name>
<surname>Tripepi</surname> <given-names>G</given-names>
</name>
<name>
<surname>Dekker</surname> <given-names>FW</given-names>
</name>
<name>
<surname>Fu</surname> <given-names>EL</given-names>
</name>
<name>
<surname>Zoccali</surname> <given-names>C</given-names>
</name>
<etal/>
</person-group>. <article-title>An introduction to inverse probability of treatment weighting in observational research</article-title>. <source>Clin Kidney J</source>. (<year>2022</year>) <volume>15</volume>:<fpage>14</fpage>&#x2013;<lpage>20</lpage>. doi:&#xa0;<pub-id pub-id-type="doi">10.1093/ckj/sfab158</pub-id>, PMID: <pub-id pub-id-type="pmid">35035932</pub-id></citation></ref>
<ref id="B22">
<label>22</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Bruton</surname> <given-names>OC</given-names>
</name>
</person-group>. <article-title>Agammaglobulinemia</article-title>. <source>Pediatrics</source>. (<year>1952</year>) <volume>9</volume>:<page-range>722&#x2013;8</page-range>. doi:&#xa0;<pub-id pub-id-type="doi">10.1542/peds.9.6.722</pub-id>
</citation></ref>
<ref id="B23">
<label>23</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Rodriguez</surname> <given-names>WJ</given-names>
</name>
<name>
<surname>Gruber</surname> <given-names>WC</given-names>
</name>
<name>
<surname>Groothuis</surname> <given-names>JR</given-names>
</name>
<name>
<surname>Simoes</surname> <given-names>EA</given-names>
</name>
<name>
<surname>Rosas</surname> <given-names>AJ</given-names>
</name>
<name>
<surname>Lepow</surname> <given-names>M</given-names>
</name>
<etal/>
</person-group>. <article-title>Respiratory syncytial virus immune globulin treatment of RSV lower respiratory tract infection in previously healthy children</article-title>. <source>Pediatrics</source>. (<year>1997</year>) <volume>100</volume>:<page-range>937&#x2013;42</page-range>. doi:&#xa0;<pub-id pub-id-type="doi">10.1542/peds.100.6.937</pub-id>, PMID: <pub-id pub-id-type="pmid">9374560</pub-id></citation></ref>
<ref id="B24">
<label>24</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Mochizuki</surname> <given-names>H</given-names>
</name>
<name>
<surname>Todokoro</surname> <given-names>M</given-names>
</name>
<name>
<surname>Arakawa</surname> <given-names>H</given-names>
</name>
</person-group>. <article-title>RS virus-induced inflammation and the intracellular glutathione redox state in cultured human airway epithelial cells</article-title>. <source>Inflammation</source>. (<year>2009</year>) <volume>32</volume>:<page-range>252&#x2013;64</page-range>. doi:&#xa0;<pub-id pub-id-type="doi">10.1007/s10753-009-9128-0</pub-id>, PMID: <pub-id pub-id-type="pmid">19548075</pub-id></citation></ref>
<ref id="B25">
<label>25</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Waghmare</surname> <given-names>A</given-names>
</name>
<name>
<surname>Englund</surname> <given-names>JA</given-names>
</name>
<name>
<surname>Boeckh</surname> <given-names>M</given-names>
</name>
</person-group>. <article-title>How I treat respiratory viral infections in the setting of intensive chemotherapy or hematopoietic cell transplantation</article-title>. <source>Blood</source>. (<year>2016</year>) <volume>127</volume>:<page-range>2682&#x2013;92</page-range>. doi:&#xa0;<pub-id pub-id-type="doi">10.1182/blood-2016-01-634873</pub-id>, PMID: <pub-id pub-id-type="pmid">26968533</pub-id></citation></ref>
<ref id="B26">
<label>26</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Sakoulas</surname> <given-names>G</given-names>
</name>
<name>
<surname>Geriak</surname> <given-names>M</given-names>
</name>
<name>
<surname>Kullar</surname> <given-names>R</given-names>
</name>
<name>
<surname>Greenwood</surname> <given-names>KL</given-names>
</name>
<name>
<surname>Habib</surname> <given-names>M</given-names>
</name>
<name>
<surname>Vyas</surname> <given-names>A</given-names>
</name>
<etal/>
</person-group>. <article-title>Intravenous immunoglobulin (IVIG) significantly reduces respiratory morbidity in COVID-19 pneumonia: a prospective randomized trial</article-title>. <source>medRxiv</source>. (<year>2020</year>). doi:&#xa0;<pub-id pub-id-type="doi">10.1101/2020.07.20.20157891</pub-id>
</citation></ref>
<ref id="B27">
<label>27</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Xiang</surname> <given-names>HR</given-names>
</name>
<name>
<surname>Cheng</surname> <given-names>X</given-names>
</name>
<name>
<surname>Li</surname> <given-names>Y</given-names>
</name>
<name>
<surname>Luo</surname> <given-names>WW</given-names>
</name>
<name>
<surname>Zhang</surname> <given-names>QZ</given-names>
</name>
<name>
<surname>Peng</surname> <given-names>WX</given-names>
</name>
</person-group>. <article-title>Efficacy of IVIG (intravenous immunoglobulin) for corona virus disease (COVID-19): A meta-analysis</article-title>. <source>Int Immunopharmacol</source>. (<year>2021</year>) <volume>96</volume>:<fpage>107732</fpage>. doi:&#xa0;<pub-id pub-id-type="doi">10.1016/j.intimp.2021.107732</pub-id>, PMID: <pub-id pub-id-type="pmid">34162133</pub-id></citation></ref>
<ref id="B28">
<label>28</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Salehi</surname> <given-names>M</given-names>
</name>
<name>
<surname>Mehni</surname> <given-names>MB</given-names>
</name>
<name>
<surname>Akbarian</surname> <given-names>M</given-names>
</name>
<name>
<surname>Ghazi</surname> <given-names>SF</given-names>
</name>
<name>
<surname>Rad</surname> <given-names>NK</given-names>
</name>
<name>
<surname>Moghaddam</surname> <given-names>OM</given-names>
</name>
<etal/>
</person-group>. <article-title>The outcome of using intravenous immunoglobulin (IVIG) in critically ill COVID-19 patients&#x2019;: a retrospective, multi-centric cohort study</article-title>. <source>Eur J Med Res</source>. (<year>2022</year>) <volume>27</volume>:<fpage>18</fpage>. doi:&#xa0;<pub-id pub-id-type="doi">10.1186/s40001-022-00637-8</pub-id>, PMID: <pub-id pub-id-type="pmid">35115056</pub-id></citation></ref>
<ref id="B29">
<label>29</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Marcec</surname> <given-names>R</given-names>
</name>
<name>
<surname>Dodig</surname> <given-names>VM</given-names>
</name>
<name>
<surname>Radanovic</surname> <given-names>I</given-names>
</name>
<name>
<surname>Likic</surname> <given-names>R</given-names>
</name>
</person-group>. <article-title>Intravenous immunoglobulin (IVIg) therapy in hospitalized adult COVID-19 patients: A systematic review and meta-analysis</article-title>. <source>Rev Med Virol</source>. (<year>2022</year>) <volume>32</volume>:<elocation-id>e2397</elocation-id>. doi:&#xa0;<pub-id pub-id-type="doi">10.1002/rmv.2397</pub-id>, PMID: <pub-id pub-id-type="pmid">36097650</pub-id></citation></ref>
<ref id="B30">
<label>30</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Hemming</surname> <given-names>VG</given-names>
</name>
<name>
<surname>Rodriguez</surname> <given-names>W</given-names>
</name>
<name>
<surname>Kim</surname> <given-names>HW</given-names>
</name>
<name>
<surname>Brandt</surname> <given-names>CD</given-names>
</name>
<name>
<surname>Parrott</surname> <given-names>RH</given-names>
</name>
<name>
<surname>Burch</surname> <given-names>B</given-names>
</name>
<etal/>
</person-group>. <article-title>Intravenous immunoglobulin treatment of respiratory syncytial virus infections in infants and young children</article-title>. <source>Antimicrob Agents Chemother</source>. (<year>1987</year>) <volume>31</volume>:<page-range>1882&#x2013;6</page-range>. doi:&#xa0;<pub-id pub-id-type="doi">10.1128/AAC.31.12.1882</pub-id>, PMID: <pub-id pub-id-type="pmid">3439796</pub-id></citation></ref>
<ref id="B31">
<label>31</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Sanders</surname> <given-names>SL</given-names>
</name>
<name>
<surname>Agwan</surname> <given-names>S</given-names>
</name>
<name>
<surname>Hassan</surname> <given-names>M</given-names>
</name>
<name>
<surname>van Driel</surname> <given-names>ML</given-names>
</name>
<name>
<surname>Del Mar</surname> <given-names>CB</given-names>
</name>
</person-group>. <article-title>Immunoglobulin treatment for hospitalised infants and young children with respiratory syncytial virus infection</article-title>. <source>Cochrane Database Syst Rev</source>. (<year>2019</year>) <volume>8</volume>:<fpage>CD009417</fpage>. doi:&#xa0;<pub-id pub-id-type="doi">10.1002/14651858.CD009417.pub2</pub-id>, PMID: <pub-id pub-id-type="pmid">31446622</pub-id></citation></ref>
<ref id="B32">
<label>32</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Bondi</surname> <given-names>M</given-names>
</name>
<name>
<surname>Engel-Haber</surname> <given-names>E</given-names>
</name>
<name>
<surname>Wolff</surname> <given-names>J</given-names>
</name>
<name>
<surname>Grosman-Rimon</surname> <given-names>L</given-names>
</name>
<name>
<surname>Bloch</surname> <given-names>A</given-names>
</name>
<name>
<surname>Zeilig</surname> <given-names>G</given-names>
</name>
</person-group>. <article-title>Functional outcomes following inpatient rehabilitation of Guillain-Barr&#xe9; syndrome patients: Intravenous immunoglobulins versus plasma exchange</article-title>. <source>NeuroRehabilitation</source>. (<year>2021</year>) <volume>48</volume>:<page-range>543&#x2013;51</page-range>. doi:&#xa0;<pub-id pub-id-type="doi">10.3233/NRE-201640</pub-id>, PMID: <pub-id pub-id-type="pmid">34024788</pub-id></citation></ref>
<ref id="B33">
<label>33</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Charra</surname> <given-names>B</given-names>
</name>
<name>
<surname>Hachimi</surname> <given-names>A</given-names>
</name>
<name>
<surname>Benslama</surname> <given-names>A</given-names>
</name>
<name>
<surname>Motaouakkil</surname> <given-names>S</given-names>
</name>
</person-group>. <article-title>Intravenous immunoglobulin vs plasma exchange in treatment of mechanically ventilated adults with Guillain-Barr&#xe9; syndrome</article-title>. <source>Pan Afr Med J</source>. (<year>2014</year>) <volume>18</volume>:<fpage>35</fpage>. doi:&#xa0;<pub-id pub-id-type="doi">10.11604/pamj.2014.18.35.2911</pub-id>, PMID: <pub-id pub-id-type="pmid">25368724</pub-id></citation></ref>
<ref id="B34">
<label>34</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Tedla</surname> <given-names>FM</given-names>
</name>
<name>
<surname>Roche-Recinos</surname> <given-names>A</given-names>
</name>
<name>
<surname>Brar</surname> <given-names>A</given-names>
</name>
</person-group>. <article-title>Intravenous immunoglobulin in kidney transplantation</article-title>. <source>Curr Opin Organ Transplant</source>. (<year>2015</year>) <volume>20</volume>:<page-range>630&#x2013;7</page-range>. doi:&#xa0;<pub-id pub-id-type="doi">10.1097/MOT.0000000000000250</pub-id>, PMID: <pub-id pub-id-type="pmid">26536425</pub-id></citation></ref>
<ref id="B35">
<label>35</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Lee</surname> <given-names>CY</given-names>
</name>
<name>
<surname>Lin</surname> <given-names>WC</given-names>
</name>
<name>
<surname>Wu</surname> <given-names>MS</given-names>
</name>
<name>
<surname>Yang</surname> <given-names>CY</given-names>
</name>
<name>
<surname>Yeh</surname> <given-names>CC</given-names>
</name>
<name>
<surname>Tsai</surname> <given-names>MK</given-names>
</name>
</person-group>. <article-title>Repeated cycles of high-dose intravenous immunoglobulin and plasmapheresis for treatment of late antibody-mediated rejection of renal transplants</article-title>. <source>J Formos Med Assoc</source>. (<year>2016</year>) <volume>115</volume>:<page-range>845&#x2013;52</page-range>. doi:&#xa0;<pub-id pub-id-type="doi">10.1016/j.jfma.2016.07.007</pub-id>, PMID: <pub-id pub-id-type="pmid">27542515</pub-id></citation></ref>
<ref id="B36">
<label>36</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Bucuvalas</surname> <given-names>J</given-names>
</name>
</person-group>. <article-title>Long-term outcomes in pediatric liver transplantation</article-title>. <source>Liver Transpl</source>. (<year>2009</year>) <volume>15 Suppl 2</volume>:<fpage>S6</fpage>&#x2013;<lpage>S11</lpage>. doi:&#xa0;<pub-id pub-id-type="doi">10.1002/lt.v15.2s</pub-id>
</citation></ref>
<ref id="B37">
<label>37</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Kornberg</surname> <given-names>A</given-names>
</name>
</person-group>. <article-title>Intravenous immunoglobulins in liver transplant patients: Perspectives of clinical immune modulation</article-title>. <source>World J Hepatol</source>. (<year>2015</year>) <volume>7</volume>:<page-range>1494&#x2013;508</page-range>. doi:&#xa0;<pub-id pub-id-type="doi">10.4254/wjh.v7.i11.1494</pub-id>, PMID: <pub-id pub-id-type="pmid">26085909</pub-id></citation></ref>
<ref id="B38">
<label>38</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Parks</surname> <given-names>T</given-names>
</name>
<name>
<surname>Wilson</surname> <given-names>C</given-names>
</name>
<name>
<surname>Curtis</surname> <given-names>N</given-names>
</name>
<name>
<surname>Norrby-Teglund</surname> <given-names>A</given-names>
</name>
<name>
<surname>Sriskandan</surname> <given-names>S</given-names>
</name>
</person-group>. <article-title>Polyspecific intravenous immunoglobulin in clindamycin-treated patients with streptococcal toxic shock syndrome: A systematic review and meta-analysis</article-title>. <source>Clin Infect Dis</source>. (<year>2018</year>) <volume>67</volume>:<page-range>1434&#x2013;6</page-range>. doi:&#xa0;<pub-id pub-id-type="doi">10.1093/cid/ciy401</pub-id>, PMID: <pub-id pub-id-type="pmid">29788397</pub-id></citation></ref>
<ref id="B39">
<label>39</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Liu</surname> <given-names>CH</given-names>
</name>
<name>
<surname>Chiu</surname> <given-names>LC</given-names>
</name>
<name>
<surname>Lee</surname> <given-names>CC</given-names>
</name>
<name>
<surname>Chan</surname> <given-names>TM</given-names>
</name>
</person-group>. <article-title>Case Report: High-dose steroid and IVIG&#xa0;successful treatment in a case of COVID-19-associated autoimmune encephalitis:&#xa0;a literature review</article-title>. <source>Front Immunol</source>. (<year>2023</year>) <volume>14</volume>:<elocation-id>1240089</elocation-id>. doi:&#xa0;<pub-id pub-id-type="doi">10.3389/fimmu.2023.1240089</pub-id>, PMID: <pub-id pub-id-type="pmid">37809102</pub-id></citation></ref>
<ref id="B40">
<label>40</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Liu</surname> <given-names>X</given-names>
</name>
<name>
<surname>Cao</surname> <given-names>W</given-names>
</name>
<name>
<surname>Li</surname> <given-names>T</given-names>
</name>
</person-group>. <article-title>High-dose intravenous immunoglobulins in the treatment of severe acute respiratory viral pneumonia: the known mechanisms and clinical effects</article-title>. <source>Front Immunol</source>. (<year>2020</year>) <volume>11</volume>:<elocation-id>1660</elocation-id>. doi:&#xa0;<pub-id pub-id-type="doi">10.3389/fimmu.2020.01660</pub-id>, PMID: <pub-id pub-id-type="pmid">32760407</pub-id></citation></ref>
<ref id="B41">
<label>41</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Lee</surname> <given-names>KY</given-names>
</name>
</person-group>. <article-title>Pneumonia, acute respiratory distress syndrome, and early immune-modulator therapy</article-title>. <source>Int J Mol Sci</source>. (<year>2017</year>) <volume>18</volume>:<fpage>388</fpage>&#x2013;<lpage>402</lpage>. doi:&#xa0;<pub-id pub-id-type="doi">10.3390/ijms18020388</pub-id>, PMID: <pub-id pub-id-type="pmid">28208675</pub-id></citation></ref>
<ref id="B42">
<label>42</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Rhim</surname> <given-names>JW</given-names>
</name>
<name>
<surname>Lee</surname> <given-names>KY</given-names>
</name>
<name>
<surname>Youn</surname> <given-names>YS</given-names>
</name>
<name>
<surname>Kang</surname> <given-names>JH</given-names>
</name>
<name>
<surname>Kim</surname> <given-names>JC</given-names>
</name>
</person-group>. <article-title>Epidemiological and clinical&#xa0;characteristics of childhood pandemic 2009 H1N1 virus infection: an observational cohort study</article-title>. <source>BMC Infect Dis</source>. (<year>2011</year>) <volume>11</volume>:<page-range>225&#x2013;32</page-range>. doi:&#xa0;<pub-id pub-id-type="doi">10.1186/1471-2334-11-225</pub-id>, PMID: <pub-id pub-id-type="pmid">21864391</pub-id></citation></ref>
<ref id="B43">
<label>43</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Emanuel</surname> <given-names>D</given-names>
</name>
<name>
<surname>Cunningham</surname> <given-names>I</given-names>
</name>
<name>
<surname>Jules-Elysee</surname> <given-names>K</given-names>
</name>
<name>
<surname>Brochstein</surname> <given-names>JA</given-names>
</name>
</person-group>. <article-title>Cytomegalovirus pneumonia after bone marrow transplantation successfully treated with the combination of ganciclovir and high-dose intravenous immune globulin</article-title>. <source>Ann Intern Med</source>. (<year>1988</year>) <volume>109</volume>:<page-range>777&#x2013;82</page-range>. doi:&#xa0;<pub-id pub-id-type="doi">10.7326/0003-4819-109-10-777</pub-id>, PMID: <pub-id pub-id-type="pmid">2847609</pub-id></citation></ref>
<ref id="B44">
<label>44</label>
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Ljungman</surname> <given-names>P</given-names>
</name>
<name>
<surname>Engelhard</surname> <given-names>D</given-names>
</name>
<name>
<surname>Link</surname> <given-names>H</given-names>
</name>
<name>
<surname>Biron</surname> <given-names>P</given-names>
</name>
<name>
<surname>Brandt</surname> <given-names>L</given-names>
</name>
<name>
<surname>Brunet</surname> <given-names>S</given-names>
</name>
<etal/>
</person-group>. <article-title>Treatment of interstitial pneumonitis due to cytomegalovirus with ganciclovir and intravenous immune globulin: experience of European Bone Marrow Transplant Group</article-title>. <source>Clin Infect Dis</source>. (<year>1992</year>) <volume>14</volume>:<page-range>831&#x2013;5</page-range>. doi:&#xa0;<pub-id pub-id-type="doi">10.1093/clinids/14.4.831</pub-id>, PMID: <pub-id pub-id-type="pmid">1315585</pub-id></citation></ref>
</ref-list>
<app-group>
<app id="app1">
<title>APPENDIX A</title>
<table-wrap>
<caption>
<p>
<bold>Acute Viral Respiratory Tract Infections ICD Codes.</bold>
</p>
</caption>
<table frame="hsides">
<thead>
<tr>
<th valign="middle" align="left">Viral Respiratory Tract Infections</th>
<th valign="middle" align="left">ICD-9</th>
<th valign="middle" align="left">ICD-10</th>
</tr>
</thead>
<tbody>
<tr>
<td valign="top" align="left">RSV (acute bronchiolitis due to respiratory syncytial virus)</td>
<td valign="top" align="left">466.11</td>
<td valign="top" align="left">J21.0</td>
</tr>
<tr>
<td valign="top" align="left">RSV (respiratory syncytial virus infection)</td>
<td valign="top" align="left"/>
<td valign="top" align="left">B97.4</td>
</tr>
<tr>
<td valign="top" align="left">RSV (respiratory syncytial virus pneumonia)</td>
<td valign="top" align="left">480.1</td>
<td valign="top" align="left">J12.1</td>
</tr>
<tr>
<td valign="top" align="left">RSV bronchitis</td>
<td valign="top" align="left"/>
<td valign="top" align="left">J20.5</td>
</tr>
<tr>
<td valign="top" align="left">Positive sputum culture for RSV</td>
<td valign="top" align="left"/>
<td valign="top" align="left">R84.5</td>
</tr>
<tr>
<td valign="top" align="left">Acute bronchitis due to parainfluenza virus</td>
<td valign="top" align="left"/>
<td valign="top" align="left">J20.4</td>
</tr>
<tr>
<td valign="top" align="left">Acute bronchitis due to Rhinovirus</td>
<td valign="top" align="left"/>
<td valign="top" align="left">J20.6</td>
</tr>
<tr>
<td valign="top" align="left">Parainfluenza virus bronchopneumonia</td>
<td valign="top" align="left"/>
<td valign="top" align="left">J12.2</td>
</tr>
<tr>
<td valign="top" align="left">Parainfluenza virus infection</td>
<td valign="top" align="left"/>
<td valign="top" align="left">B33.8</td>
</tr>
<tr>
<td valign="top" align="left">Parainfluenza type 1 infection; Rhinovirus</td>
<td valign="top" align="left"/>
<td valign="top" align="left">B34.8</td>
</tr>
<tr>
<td valign="top" align="left">Acute bronchiolitis due to human metapneumovirus</td>
<td valign="top" align="left"/>
<td valign="top" align="left">J21.1</td>
</tr>
<tr>
<td valign="top" align="left">Pneumonia due to human metapneumovirus</td>
<td valign="top" align="left"/>
<td valign="top" align="left">J12.3</td>
</tr>
<tr>
<td valign="top" align="left">Infection due to human metapneumovirus</td>
<td valign="top" align="left"/>
<td valign="top" align="left">B97.81</td>
</tr>
<tr>
<td valign="top" align="left">Pneumonia due to adenovirus</td>
<td valign="top" align="left">480.0</td>
<td valign="top" align="left">J12.0</td>
</tr>
</tbody>
</table>
<table-wrap-foot>
<fn>
<p>ICD, International Classification of Diseases; RSV, respiratory syncytial virus.</p>
</fn>
</table-wrap-foot>
</table-wrap>
</app>
<app id="app2">
<title>APPENDIX B</title>
<table-wrap>
<caption>
<p>
<bold>Immune Deficiency ICD Codes</bold>.</p>
</caption>
<table frame="hsides">
<thead>
<tr>
<th valign="middle" align="left">Immune Deficiency Diagnosis</th>
<th valign="middle" align="left">Sample</th>
<th valign="middle" align="left">ICD 9</th>
<th valign="middle" align="left">ICD 10</th>
</tr>
</thead>
<tbody>
<tr>
<td valign="top" align="left">Hospitalized for chemotherapy treatment</td>
<td valign="top" align="center">1</td>
<td valign="top" align="left">V58.11</td>
<td valign="top" align="left">Z51.11</td>
</tr>
<tr>
<td valign="top" align="left">Complication of chemotherapy</td>
<td valign="top" align="center">1</td>
<td valign="top" align="left"/>
<td valign="top" align="left">T88.7XXA</td>
</tr>
<tr>
<td valign="top" align="left">Cancer</td>
<td valign="top" align="center">1</td>
<td valign="top" align="left">199.1</td>
<td valign="top" align="left">C80.1</td>
</tr>
<tr>
<td valign="top" align="left">History of immunosuppressive therapy</td>
<td valign="top" align="center">1</td>
<td valign="top" align="left">V87.46</td>
<td valign="top" align="left">Z92.25</td>
</tr>
<tr>
<td valign="top" align="left">Transplant, organ</td>
<td valign="top" align="center">1</td>
<td valign="top" align="left">V42</td>
<td valign="top" align="left">Z94.9</td>
</tr>
<tr>
<td valign="top" align="left">Kidney replaced by transplant</td>
<td valign="top" align="center">1</td>
<td valign="top" align="left">V42.0</td>
<td valign="top" align="left">Z94.0</td>
</tr>
<tr>
<td valign="top" align="left">Heart replaced by transplant</td>
<td valign="top" align="center">1</td>
<td valign="top" align="left">V42.1</td>
<td valign="top" align="left">Z94.1</td>
</tr>
<tr>
<td valign="top" align="left">Bone replaced by transplant</td>
<td valign="top" align="center">1</td>
<td valign="top" align="left">V42.4</td>
<td valign="top" align="left">Z94.81</td>
</tr>
<tr>
<td valign="top" align="left">Lung replaced by transplant</td>
<td valign="top" align="center">1</td>
<td valign="top" align="left">V42.6</td>
<td valign="top" align="left">Z94.2</td>
</tr>
<tr>
<td valign="top" align="left">Liver replaced by transplant</td>
<td valign="top" align="center">1</td>
<td valign="top" align="left">V42.7</td>
<td valign="top" align="left">Z94.4</td>
</tr>
<tr>
<td valign="top" align="left">Other specified organ or tissue replaced by transplant</td>
<td valign="top" align="center">1</td>
<td valign="top" align="left">V42.8</td>
<td valign="top" align="left"/>
</tr>
<tr>
<td valign="top" align="left">Unspecified organ or tissue replaced by transplant</td>
<td valign="top" align="center">1</td>
<td valign="top" align="left">V42.9</td>
<td valign="top" align="left"/>
</tr>
<tr>
<td valign="top" align="left">Bone marrow replaced by transplant</td>
<td valign="top" align="center">1</td>
<td valign="top" align="left">V42.81</td>
<td valign="top" align="left"/>
</tr>
<tr>
<td valign="top" align="left">Transplant follow up</td>
<td valign="top" align="center">1</td>
<td valign="top" align="left"/>
<td valign="top" align="left">Z48.298</td>
</tr>
<tr>
<td valign="top" align="left">Transplant recipient</td>
<td valign="top" align="center">1</td>
<td valign="top" align="left"/>
<td valign="top" align="left">Z94.89</td>
</tr>
<tr>
<td valign="top" align="left">History of bone marrow transplant</td>
<td valign="top" align="center">1</td>
<td valign="top" align="left"/>
<td valign="top" align="left">Z94.81</td>
</tr>
<tr>
<td valign="top" align="left">History of organ or tissue transplant</td>
<td valign="top" align="center">1</td>
<td valign="top" align="left"/>
<td valign="top" align="left">Z94.9</td>
</tr>
<tr>
<td valign="top" align="left">Complications, organ transplant</td>
<td valign="top" align="center">1</td>
<td valign="top" align="left">996.80</td>
<td valign="top" align="left">T86.90</td>
</tr>
<tr>
<td valign="top" align="left">Primary Immunodeficiency Disorder</td>
<td valign="top" align="center">1, 2</td>
<td valign="top" align="left">279.0X, 279.12, 279.2X</td>
<td valign="top" align="left">D80.1, D80.2, D80.3, D80.4, D80.5, D80.7, D81.0, D81.1, D81.2, D81.6, D81.7, D81.89, D81.9, D82.0, D83.0, D83.1, D83.2, D83.8, D83.9</td>
</tr>
<tr>
<td valign="top" align="left">Immunodeficiency disorder due to antibody deficiency</td>
<td valign="top" align="center">1</td>
<td valign="top" align="left"/>
<td valign="top" align="left">D80.6</td>
</tr>
<tr>
<td valign="top" align="left">Immunodeficiency due to chemotherapy</td>
<td valign="top" align="center">1</td>
<td valign="top" align="left">V58.11</td>
<td valign="top" align="left">Z79.899</td>
</tr>
<tr>
<td valign="top" align="left">Immunodeficiency secondary to neoplasm</td>
<td valign="top" align="center">1</td>
<td valign="top" align="left"/>
<td valign="top" align="left">D84.8, D49.9</td>
</tr>
<tr>
<td valign="top" align="left">CVID (Common Variable Immunodeficiency)</td>
<td valign="top" align="center">1, 2</td>
<td valign="top" align="left">279.06</td>
<td valign="top" align="left">D83.9</td>
</tr>
<tr>
<td valign="top" align="left">Deficiency, humoral</td>
<td valign="top" align="center">1, 2</td>
<td valign="top" align="left">279.00</td>
<td valign="top" align="left"/>
</tr>
<tr>
<td valign="top" align="left">Immunodeficiency associated with major defect</td>
<td valign="top" align="center">1</td>
<td valign="top" align="left"/>
<td valign="top" align="left">D82.9</td>
</tr>
<tr>
<td valign="top" align="left">Immunodeficiency with predominantly antibody defects</td>
<td valign="top" align="center">1</td>
<td valign="top" align="left"/>
<td valign="top" align="left">D80.9</td>
</tr>
<tr>
<td valign="top" align="left">Combined Immunodeficiency, unspecified</td>
<td valign="top" align="center">1, 2</td>
<td valign="top" align="left">279.2</td>
<td valign="top" align="left">D81.9</td>
</tr>
<tr>
<td valign="top" align="left">Disorder of immune system</td>
<td valign="top" align="center">1</td>
<td valign="top" align="left"/>
<td valign="top" align="left">D89.9</td>
</tr>
<tr>
<td valign="top" align="left">Disorder of Lymphatic system</td>
<td valign="top" align="center">1</td>
<td valign="top" align="left"/>
<td valign="top" align="left">I89.9</td>
</tr>
<tr>
<td valign="top" align="left">Encounter for antineoplastic immunotherapy</td>
<td valign="top" align="center">1</td>
<td valign="top" align="left">V58.12</td>
<td valign="top" align="left">Z51.12</td>
</tr>
</tbody>
</table>
<table-wrap-foot>
<fn>
<p>ICD, International Classification of Diseases.</p>
</fn>
</table-wrap-foot>
</table-wrap>
</app>
</app-group>
</back>
</article>