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<front>
<journal-meta>
<journal-id journal-id-type="publisher-id">Front. Surg.</journal-id>
<journal-title>Frontiers in Surgery</journal-title>
<abbrev-journal-title abbrev-type="pubmed">Front. Surg.</abbrev-journal-title>
<issn pub-type="epub">2296-875X</issn>
<publisher>
<publisher-name>Frontiers Media S.A.</publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.3389/fsurg.2022.870946</article-id>
<article-categories>
<subj-group subj-group-type="heading">
<subject>Surgery</subject>
<subj-group>
<subject>Original Research</subject>
</subj-group>
</subj-group>
</article-categories>
<title-group>
<article-title>Does Chronic Kidney Disease Really Affect the Complications and Prognosis After Liver Resection for Hepatocellular Carcinoma? A Meta-Analysis</article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name><surname>Liu</surname> <given-names>Xiao-Yu</given-names></name>
<xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
<xref ref-type="author-notes" rid="fn002"><sup>&#x02020;</sup></xref>
<uri xlink:href="http://loop.frontiersin.org/people/1368118/overview"/>
</contrib>
<contrib contrib-type="author">
<name><surname>Zhao</surname> <given-names>Zhi-Qiang</given-names></name>
<xref ref-type="aff" rid="aff2"><sup>2</sup></xref>
<xref ref-type="author-notes" rid="fn002"><sup>&#x02020;</sup></xref>
</contrib>
<contrib contrib-type="author">
<name><surname>Cheng</surname> <given-names>Yu-Xi</given-names></name>
<xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
<uri xlink:href="http://loop.frontiersin.org/people/1368514/overview"/>
</contrib>
<contrib contrib-type="author">
<name><surname>Tao</surname> <given-names>Wei</given-names></name>
<xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
<uri xlink:href="http://loop.frontiersin.org/people/1442644/overview"/>
</contrib>
<contrib contrib-type="author">
<name><surname>Yuan</surname> <given-names>Chao</given-names></name>
<xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
<uri xlink:href="http://loop.frontiersin.org/people/1442360/overview"/>
</contrib>
<contrib contrib-type="author">
<name><surname>Zhang</surname> <given-names>Bin</given-names></name>
<xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
<uri xlink:href="http://loop.frontiersin.org/people/1393909/overview"/>
</contrib>
<contrib contrib-type="author" corresp="yes">
<name><surname>Wang</surname> <given-names>Chun-Yi</given-names></name>
<xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
<xref ref-type="corresp" rid="c001"><sup>&#x0002A;</sup></xref>
</contrib>
</contrib-group>
<aff id="aff1"><sup>1</sup><institution>Department of Gastrointestinal Surgery, The First Affiliated Hospital of Chongqing Medical University</institution>, <addr-line>Chongqing</addr-line>, <country>China</country></aff>
<aff id="aff2"><sup>2</sup><institution>Department of General Surgery, Qijiang Hospital of the First Affiliated Hospital of Chongqing Medical University</institution>, <addr-line>Chongqing</addr-line>, <country>China</country></aff>
<author-notes>
<fn fn-type="edited-by"><p>Edited by: Mattia Garancini, San Gerardo Hospital, Italy</p></fn>
<fn fn-type="edited-by"><p>Reviewed by: Farzad Kakaee, Tabriz University of Medical Sciences, Iran; Chai Hong Rim, Korea University, South Korea</p></fn>
<corresp id="c001">&#x0002A;Correspondence: Chun-Yi Wang <email>1962989853&#x00040;qq.com</email></corresp>
<fn fn-type="other" id="fn001"><p>This article was submitted to Visceral Surgery, a section of the journal Frontiers in Surgery</p></fn>
<fn fn-type="equal" id="fn002"><p>&#x02020;These authors have contributed equally to this work</p></fn></author-notes>
<pub-date pub-type="epub">
<day>06</day>
<month>04</month>
<year>2022</year>
</pub-date>
<pub-date pub-type="collection">
<year>2022</year>
</pub-date>
<volume>9</volume>
<elocation-id>870946</elocation-id>
<history>
<date date-type="received">
<day>07</day>
<month>02</month>
<year>2022</year>
</date>
<date date-type="accepted">
<day>10</day>
<month>03</month>
<year>2022</year>
</date>
</history>
<permissions>
<copyright-statement>Copyright &#x000A9; 2022 Liu, Zhao, Cheng, Tao, Yuan, Zhang and Wang.</copyright-statement>
<copyright-year>2022</copyright-year>
<copyright-holder>Liu, Zhao, Cheng, Tao, Yuan, Zhang and Wang</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>Purpose</title>
<p>The purpose of this meta-analysis was to analyze whether chronic kidney disease (CKD) affected the complications and prognosis after liver resection for hepatocellular carcinoma.</p></sec>
<sec>
<title>Methods</title>
<p>The PubMed, Embase, and Cochrane Library databases were searched from inception to 22 February 2022 to find eligible studies. Complications, overall survival (OS), and disease-free survival (DFS) were collected, and this meta-analysis was performed with RevMan 5.3.</p></sec>
<sec>
<title>Results</title>
<p>A total of nine studies including 6,541 patients were included in this meta-analysis. After pooling all baseline information, the CKD group had a higher rate of Child-Pugh grade B than the Non-CKD group (OR = 1.58, 95% CI = 1.3 to 1.93, <italic>P</italic> &#x0003C; 0.00001). As for surgery-related information, the CKD group had larger blood loss (MD = &#x02212;404.79, 95% CI = &#x02212;509.70 to &#x02212;299.88, <italic>P</italic> &#x0003C; 0.00001), and higher rate of blood transfusion (OR = 2.47, 95% CI = 1.85 to 3.3, <italic>P</italic> &#x0003C; 0.00001). In terms of complications, the CKD group had a higher rate of overall complications (OR = 2.1, 95% CI = 1.57 to 2.81, <italic>P</italic> &#x0003C; 0.00001) and a higher rate of &#x02265; grade III complications (OR = 2.04, 95% CI = 1.57 to 2.81, <italic>P</italic> = 0.0002). The CKD group had poor OS compared with the non-CKD group (HR = 1.28, 95% CI = 1.1 to 1.49, <italic>P</italic> = 0.001). However, in terms of DFS, no significant difference was found (HR = 1.11, 95% CI = 0.96 to 1.28, <italic>P</italic> = 0.16).</p></sec>
<sec>
<title>Conclusion</title>
<p>Preexisting CKD was associated with higher ratio of complications and poor OS.</p></sec></abstract>
<kwd-group>
<kwd>chronic kidney disease</kwd>
<kwd>hepatocellular carcinoma</kwd>
<kwd>overall survival</kwd>
<kwd>complications</kwd>
<kwd>meta-analysis</kwd>
</kwd-group>
<counts>
<fig-count count="4"/>
<table-count count="2"/>
<equation-count count="0"/>
<ref-count count="33"/>
<page-count count="8"/>
<word-count count="4310"/>
</counts>
</article-meta>
</front>
<body>
<sec sec-type="intro" id="s1">
<title>Introduction</title>
<p>Hepatocellular carcinoma (HCC) is the fifth most common malignant tumor and the fourth most common cause of cancer-related deaths in the world (<xref ref-type="bibr" rid="B1">1</xref>, <xref ref-type="bibr" rid="B2">2</xref>). It is estimated that 840,000 newly diagnosed HCC cases are reported each year worldwide (<xref ref-type="bibr" rid="B3">3</xref>). Liver resection is commonly radical treatment (<xref ref-type="bibr" rid="B4">4</xref>, <xref ref-type="bibr" rid="B5">5</xref>).</p>
<p>Chronic kidney disease (CKD) is a serious public health problem in the 21st century (<xref ref-type="bibr" rid="B6">6</xref>) and leads to premature death, reduced quality of life, and heavy economic burden on patients (<xref ref-type="bibr" rid="B7">7</xref>). The morbidity and mortality of CKD are increasing rapidly worldwide (<xref ref-type="bibr" rid="B8">8</xref>), and compared with the non-CKD population, the morbidity and mortality usually come from cardiovascular disease (<xref ref-type="bibr" rid="B9">9</xref>, <xref ref-type="bibr" rid="B10">10</xref>).</p>
<p>Previous studies have reported the relationship between CKD and cancer surgeries, and CKD increased complications and mortality (<xref ref-type="bibr" rid="B11">11</xref>, <xref ref-type="bibr" rid="B12">12</xref>). Multiple systems are impaired with progression of CKD (<xref ref-type="bibr" rid="B11">11</xref>), which might account for higher complications and poorer overall survival.</p>
<p>As for HCC, CKD might have a potential effect on outcomes. However, it remains controversial whether preexisting CKD has an impact on complications and prognosis after liver resection for hepatocellular carcinoma. Some studies reported that CKD had no effect on complications or prognosis; (<xref ref-type="bibr" rid="B13">13</xref>, <xref ref-type="bibr" rid="B14">14</xref>) however, other studies reported that CKD was associated with increased complications and poor prognosis (<xref ref-type="bibr" rid="B15">15</xref>, <xref ref-type="bibr" rid="B16">16</xref>). Therefore, the purpose of this meta-analysis was to analyze whether CKD affected the complications and prognosis after liver resection for hepatocellular carcinoma.</p></sec>
<sec sec-type="methods" id="s2">
<title>Methods</title>
<sec>
<title>Literature Search Strategy</title>
<p>The PubMed, Embase, and Cochrane Library databases were systematically searched by two authors, and searching date was 22 February 2022. The search strategy mainly focused on the following two items, HCC and CKD. For HCC, the search strategy was as follows: (liver cancer) OR (hepatocellular carcinoma) OR (hepatocarcinoma) OR (HCC); for CKD, the search strategy was as follows: (chronic kidney disease) OR (hemodialysis) OR (estimated glomerular filtration rate) OR (dialysis) OR (cystatin c). Then, we used &#x0201C;and&#x0201D; to combine two key words. The scope of the search strategy was limited to the Title and Abstract, and the language was limited to articles published in English.</p></sec>
<sec>
<title>Inclusion and Exclusion Criteria</title>
<p>The inclusion criteria of this meta-study were as follows: (1) Patients diagnosed with HCC and received primary liver resection; (2) The preexisting disease included CKD group and Non-CKD group; and (3) Postoperative short-term complications or long-term prognosis were reported. The exclusion criteria were as follows: (1) data that could not be extracted in the meta-analysis; and (2) research type was case report, letter to editor, comments, reviews, or and conference. Two reviewers conducted the inclusion and exclusion separately, and a disagreement was resolved by another reviewer.</p></sec>
<sec>
<title>Data Extraction</title>
<p>The extracted data were as follows: (1) first author, year of publication, country, study design, study date, definition of CKD; (2) baseline information including sex, age, tumor size, vascular invasion, intrahepatic metastases, Child-Pugh grade, and liver cirrhosis; (3) surgery-related information including blood loss, blood transfusion, and postoperative hospital stay; (4) postoperative information including overall complications, surgical site infection, bile leakage, liver failure, pleural effusion, ascites, and postoperative bleeding; and (5) overall survival (OS) and disease-free survival (DFS).</p></sec>
<sec>
<title>Quality Assessment</title>
<p>To assess the methodological quality of included retrospective studies, we adopted the Newcastle-Ottawa Scale (NOS) (<xref ref-type="bibr" rid="B17">17</xref>)If the NOS score was equal to nine points, we considered the methodological quality of a study to be high; if the NOS score was less than seven points, we considered the methodological quality of a study to be low; if the NOS score was between seven and eight, we considered the methodological quality of a research study was moderate.</p></sec>
<sec>
<title>Statistical Analysis</title>
<p>The meta-analysis was performed using RevMan 5.3 (The Cochrane Collaboration, London, United Kingdom). In this meta-analysis, pooled hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated for the OS and DFS of patients with hepatocellular carcinoma, and HRs were extracted from multivariate analyses and/or univariate analyses, or estimated from Kaplane-Meier survival curves (<xref ref-type="bibr" rid="B18">18</xref>, <xref ref-type="bibr" rid="B19">19</xref>). Continuous variables were presented as the mean and standard deviation (SD), and categorical variables were presented as proportions. For dichotomous and continuous variables, odds ratios (ORs) and mean differences (MDs), and 95% CIs were calculated. The I<sup>2</sup> value and the results of the chi-squared test were used to assess statistical heterogeneity (<xref ref-type="bibr" rid="B20">20</xref>, <xref ref-type="bibr" rid="B21">21</xref>). High heterogeneity was considered when I<sup>2</sup> &#x0003E; 50%; in such a case, a random effects model was used, and <italic>p</italic> &#x0003C; 0.1 was considered statistically significant. A fixed effects model was used when I<sup>2</sup> &#x02264; 50%, and <italic>p</italic> &#x0003C; 0.05 was considered statistically significant.</p></sec></sec>
<sec sec-type="results" id="s3">
<title>Results</title>
<sec>
<title>Study Selection</title>
<p>A total of 2,016 studies were identified in the three databases, 540 studies in Pubmed, 1,091 studies in Embase, and 385 studies in the Cochrane Library. After removing duplicate studies, 1,368 studies were left for initial screening. After that, 26 studies were accessed with full text for potential eligibility. In total, nine studies were included in this meta-analysis, and the flow chart is shown in <xref ref-type="fig" rid="F1">Figure 1</xref>.</p>
<fig id="F1" position="float">
<label>Figure 1</label>
<caption><p>Flowchart of study selection.</p></caption>
<graphic mimetype="image" mime-subtype="tiff" xlink:href="fsurg-09-870946-g0001.tif"/>
</fig></sec>
<sec>
<title>Patient Characteristics</title>
<p>Nine studies (<xref ref-type="bibr" rid="B13">13</xref>&#x02013;<xref ref-type="bibr" rid="B16">16</xref>, <xref ref-type="bibr" rid="B22">22</xref>&#x02013;<xref ref-type="bibr" rid="B26">26</xref>) with a total of 6,541 patients were included in this meta-analysis. Five studies were from Japan, and four studies were from China. The year of publication was from 2001 to 2021, and all the studies were retrospective. The definition of CKD and non-CKD was according to eGFR, dialysis, and creatinine. Newcastle-Ottawa Scale (NOS) scores were accessed in each study and are shown in <xref ref-type="table" rid="T1">Table 1</xref>.</p>
<table-wrap position="float" id="T1">
<label>Table 1</label>
<caption><p>Characteristics of the studies included in the meta-analysis.</p></caption>
<table frame="hsides" rules="groups">
<thead><tr>
<th valign="top" align="left"><bold>Author</bold></th>
<th valign="top" align="center"><bold>Year published</bold></th>
<th valign="top" align="left"><bold>Country</bold></th>
<th valign="top" align="left"><bold>Study design</bold></th>
<th valign="top" align="center"><bold>Study date</bold></th>
<th valign="top" align="center" style="border-bottom: thin solid #000000;" colspan="3"><bold>Sample size</bold></th>
<th valign="top" align="center" style="border-bottom: thin solid #000000;" colspan="2"><bold>Definition of CKD and Non-CKD</bold></th>
<th valign="top" align="center"><bold>NOS</bold></th>
</tr>
<tr>
<th/>
<th/>
<th/>
<th/>
<th/>
<th valign="top" align="center"><bold>CKD group</bold></th>
<th valign="top" align="center"><bold>Non-CKD group</bold></th>
<th valign="top" align="center"><bold>Total</bold></th>
<th valign="top" align="center"><bold>CKD group</bold></th>
<th valign="top" align="center"><bold>Non-CKD group</bold></th>
<th/>
</tr>
</thead>
<tbody>
<tr>
<td valign="top" align="left">Yoshikawa T</td>
<td valign="top" align="center">2021</td>
<td valign="top" align="left">Japan</td>
<td valign="top" align="left">Retrospective</td>
<td valign="top" align="center">2011&#x02013;2019</td>
<td valign="top" align="center">28</td>
<td valign="top" align="center">176</td>
<td valign="top" align="center">204</td>
<td valign="top" align="center">eGFR &#x0003C;45</td>
<td valign="top" align="center">eGFR &#x02265; 45</td>
<td valign="top" align="center">7</td>
</tr>
<tr>
<td valign="top" align="left">Ho SY</td>
<td valign="top" align="center">2021</td>
<td valign="top" align="left">China</td>
<td valign="top" align="left">Retrospective</td>
<td valign="top" align="center">2002&#x02212;2017</td>
<td valign="top" align="center">43</td>
<td valign="top" align="center">129</td>
<td valign="top" align="center">172</td>
<td valign="top" align="center">Dialysis</td>
<td valign="top" align="center">Non-dialysis</td>
<td valign="top" align="center">8</td>
</tr>
<tr>
<td valign="top" align="left">Shirata C</td>
<td valign="top" align="center">2018</td>
<td valign="top" align="left">Japan</td>
<td valign="top" align="left">Retrospective</td>
<td valign="top" align="center">2002&#x02013;2014</td>
<td valign="top" align="center">62</td>
<td valign="top" align="center">673</td>
<td valign="top" align="center">735</td>
<td valign="top" align="center">eGFR &#x0003C;45</td>
<td valign="top" align="center">eGFR &#x02265; 45</td>
<td valign="top" align="center">7</td>
</tr>
<tr>
<td valign="top" align="left">Yeh CC</td>
<td valign="top" align="center">2013</td>
<td valign="top" align="left">China</td>
<td valign="top" align="left">Retrospective</td>
<td valign="top" align="center">1996&#x02013;2008</td>
<td valign="top" align="center">149</td>
<td valign="top" align="center">596</td>
<td valign="top" align="center">745</td>
<td valign="top" align="center">eGFR &#x0003C;15</td>
<td valign="top" align="center">eGFR &#x02265; 15</td>
<td valign="top" align="center">8</td>
</tr>
<tr>
<td valign="top" align="left">Hsu CY</td>
<td valign="top" align="center">2012</td>
<td valign="top" align="left">China</td>
<td valign="top" align="left">Retrospective</td>
<td valign="top" align="center">NA</td>
<td valign="top" align="center">502</td>
<td valign="top" align="center">1701</td>
<td valign="top" align="center">2203</td>
<td valign="top" align="center">eGFR &#x0003C;60</td>
<td valign="top" align="center">eGFR &#x02265; 60</td>
<td valign="top" align="center">8</td>
</tr>
<tr>
<td valign="top" align="left">Orii T</td>
<td valign="top" align="center">2008</td>
<td valign="top" align="left">Japan</td>
<td valign="top" align="left">Retrospective</td>
<td valign="top" align="center">1990&#x02013;2006</td>
<td valign="top" align="center">17</td>
<td valign="top" align="center">51</td>
<td valign="top" align="center">68</td>
<td valign="top" align="center">CRF</td>
<td valign="top" align="center">Non-CRF</td>
<td valign="top" align="center">6</td>
</tr>
<tr>
<td valign="top" align="left">Toshima T</td>
<td valign="top" align="center">2012</td>
<td valign="top" align="left">Japan</td>
<td valign="top" align="left">Retrospective</td>
<td valign="top" align="center">1986&#x02013;2009</td>
<td valign="top" align="center">17</td>
<td valign="top" align="center">705</td>
<td valign="top" align="center">722</td>
<td valign="top" align="center">Cr &#x0003E; 2</td>
<td valign="top" align="center">Cr &#x02264; 2</td>
<td valign="top" align="center">7</td>
</tr>
<tr>
<td valign="top" align="left">Yeh CN</td>
<td valign="top" align="center">2005</td>
<td valign="top" align="left">China</td>
<td valign="top" align="left">Retrospective</td>
<td valign="top" align="center">1982&#x02013;2001</td>
<td valign="top" align="center">26</td>
<td valign="top" align="center">1198</td>
<td valign="top" align="center">1224</td>
<td valign="top" align="center">Dialysis</td>
<td valign="top" align="center">Non-dialysis</td>
<td valign="top" align="center">8</td>
</tr>
<tr>
<td valign="top" align="left">Cheng SB</td>
<td valign="top" align="center">2001</td>
<td valign="top" align="left">China</td>
<td valign="top" align="left">Retrospective</td>
<td valign="top" align="center">1989&#x02013;1999</td>
<td valign="top" align="center">12</td>
<td valign="top" align="center">456</td>
<td valign="top" align="center">468</td>
<td valign="top" align="center">Dialysis</td>
<td valign="top" align="center">Non-dialysis</td>
<td valign="top" align="center">7</td>
</tr>
</tbody>
</table>
<table-wrap-foot>
<p><italic>CKD, chronic kidney disease; eGFR, estimated glomerular filtration rates, mL/min/1.73 m<sup>2</sup>; CRF, chronic renal failure; Cr, creatinine, mg/dl; NOS, Newcastle-Ottawa Scale; NA, not applicable</italic>.</p>
</table-wrap-foot>
</table-wrap></sec>
<sec>
<title>Baseline Information</title>
<p>The baseline information included sex, age, tumor size, vascular invasion, intrahepatic metastases, liver cirrhosis and Child-Pugh classification, and was compared between the CKD group and the non-CKD group. After pooling all the data, the CKD group had a higher rate of Child-Pugh grade B than the non-CKD group (OR = 1.58, 95% CI = 1.3 to 1.93, <italic>P</italic> &#x0003C; 0.00001) (<xref ref-type="table" rid="T2">Table 2</xref>).</p>
<table-wrap position="float" id="T2">
<label>Table 2</label>
<caption><p>Summary of characteristics between CKD group and Non&#x02013;CKD group.</p></caption>
<table frame="hsides" rules="groups">
<thead><tr>
<th valign="top" align="left"><bold>Characteristics</bold></th>
<th valign="top" align="center"><bold>Studies</bold></th>
<th valign="top" align="center"><bold>Participants (CKD/ non&#x02013;CKD)</bold></th>
<th valign="top" align="center"><bold>Mean difference/odds ratio (95% CI)</bold></th>
<th valign="top" align="center"><bold>Heterogeneity</bold></th>
</tr>
</thead>
<tbody>
<tr>
<td valign="top" align="left">Baseline information</td>
</tr>
<tr>
<td valign="top" align="left">&#x000A0;&#x000A0;Male</td>
<td valign="top" align="center">9</td>
<td valign="top" align="center">856/5685</td>
<td valign="top" align="center">0.85 [0.72, 1.00]; <italic>P =</italic> 0.06</td>
<td valign="top" align="center">I<sup>2</sup> = 0%; <italic>P =</italic> 0.75</td>
</tr>
<tr>
<td valign="top" align="left">&#x000A0;&#x000A0;Age, year</td>
<td valign="top" align="center">5</td>
<td valign="top" align="center">605/3784</td>
<td valign="top" align="center">0.80 [&#x02212;6.69, 8.29]; <italic>P =</italic> 0.83</td>
<td valign="top" align="center">I<sup>2</sup> = 99%; <italic>P &#x0003C;</italic> 0.00001</td>
</tr>
<tr>
<td valign="top" align="left">&#x000A0;&#x000A0;Tumor size, cm</td>
<td valign="top" align="center">4</td>
<td valign="top" align="center">103/2083</td>
<td valign="top" align="center">&#x02212;0.36 [&#x02212;1.76, 1.05]; <italic>P =</italic> 0.62</td>
<td valign="top" align="center">I<sup>2</sup> = 89%; <italic>P &#x0003C;</italic> 0.00001</td>
</tr>
<tr>
<td valign="top" align="left">&#x000A0;&#x000A0;Vascular invasion</td>
<td valign="top" align="center">8</td>
<td valign="top" align="center">705/5041</td>
<td valign="top" align="center">0.86 [0.72, 1.02]; <italic>P =</italic> 0.09</td>
<td valign="top" align="center">I<sup>2</sup> = 0%; <italic>P =</italic> 0.95</td>
</tr>
<tr>
<td valign="top" align="left">&#x000A0;&#x000A0;Intrahepatic metastases</td>
<td valign="top" align="center">3</td>
<td valign="top" align="center">96/1429</td>
<td valign="top" align="center">0.73 [0.40, 1.32]; <italic>P =</italic> 0.29</td>
<td valign="top" align="center">I<sup>2</sup> = 0%; <italic>P =</italic> 0.85</td>
</tr>
<tr>
<td valign="top" align="left">&#x000A0;&#x000A0;Child&#x02013;Pugh grade A</td>
<td valign="top" align="center">8</td>
<td valign="top" align="center">707/5089</td>
<td valign="top" align="center">0.53 [0.44, 0.63]; <italic>P &#x0003C;</italic> 0.00001</td>
<td valign="top" align="center">I<sup>2</sup> = 0%; <italic>P =</italic> 0.86</td>
</tr>
<tr>
<td valign="top" align="left">&#x000A0;&#x000A0;Child&#x02013;Pugh grade B</td>
<td valign="top" align="center">7</td>
<td valign="top" align="center">679/4913</td>
<td valign="top" align="center">1.58 [1.30, 1.93]; <italic>P &#x0003C;</italic> 0.00001</td>
<td valign="top" align="center">I<sup>2</sup> = 8%; <italic>P =</italic> 0.37</td>
</tr>
<tr>
<td valign="top" align="left">&#x000A0;&#x000A0;Liver cirrhosis</td>
<td valign="top" align="center">5</td>
<td valign="top" align="center">266/2963</td>
<td valign="top" align="center">0.84 [0.64, 1.10]; <italic>P =</italic> 0.21</td>
<td valign="top" align="center">I<sup>2</sup> = 0%; <italic>P =</italic> 0.54</td>
</tr>
<tr>
<td valign="top" align="left">Surgery&#x02013;related information</td>
</tr>
<tr>
<td valign="top" align="left">&#x000A0;&#x000A0;Blood loss, mL</td>
<td valign="top" align="center">3</td>
<td valign="top" align="center">90/1954</td>
<td valign="top" align="center">&#x02212;404.79 [&#x02212;509.70, &#x02212;299.88]; <italic>P &#x0003C;</italic> 0.00001</td>
<td valign="top" align="center">I<sup>2</sup> = 0%; <italic>P =</italic> 0.67</td>
</tr>
<tr>
<td valign="top" align="left">&#x000A0;&#x000A0;Blood transfusion</td>
<td valign="top" align="center">4</td>
<td valign="top" align="center">256/2150</td>
<td valign="top" align="center">2.47 [1.85, 3.30]; <italic>P &#x0003C;</italic> 0.00001</td>
<td valign="top" align="center">I<sup>2</sup> = 3%; <italic>P =</italic> 0.38</td>
</tr>
<tr>
<td valign="top" align="left">&#x000A0;&#x000A0;Hospital stay, days</td>
<td valign="top" align="center">3</td>
<td valign="top" align="center">60/1954</td>
<td valign="top" align="center">4.07 [&#x02212;5.52, 13.67]; <italic>P =</italic> 0.41</td>
<td valign="top" align="center">I<sup>2</sup> = 90%; <italic>P &#x0003C;</italic> 0.00001</td>
</tr>
<tr>
<td valign="top" align="left">Postoperative complications</td>
</tr>
<tr>
<td valign="top" align="left">&#x000A0;&#x000A0;Surgical site infection</td>
<td valign="top" align="center">5</td>
<td valign="top" align="center">223/1984</td>
<td valign="top" align="center">2.11 [1.02, 4.38]; <italic>P =</italic> 0.04</td>
<td valign="top" align="center">I<sup>2</sup> = 16%; <italic>P =</italic> 0.31</td>
</tr>
<tr>
<td valign="top" align="left">&#x000A0;&#x000A0;Bile leakage</td>
<td valign="top" align="center">5</td>
<td valign="top" align="center">136/2061</td>
<td valign="top" align="center">1.60 [0.79, 3.27]; <italic>P =</italic> 0.19</td>
<td valign="top" align="center">I<sup>2</sup> = 0%; <italic>P =</italic> 0.61</td>
</tr>
<tr>
<td valign="top" align="left">&#x000A0;&#x000A0;Liver failure</td>
<td valign="top" align="center">3</td>
<td valign="top" align="center">194/1477</td>
<td valign="top" align="center">1.50 [0.61, 3.70]; <italic>P =</italic> 0.38</td>
<td valign="top" align="center">I<sup>2</sup> = 0%; <italic>P =</italic> 0.40</td>
</tr>
<tr>
<td valign="top" align="left">&#x000A0;&#x000A0;Pleural effusion</td>
<td valign="top" align="center">4</td>
<td valign="top" align="center">119/2010</td>
<td valign="top" align="center">2.74 [1.73, 4.32]; <italic>P &#x0003C;</italic> 0.0001</td>
<td valign="top" align="center">I<sup>2</sup> = 22%; <italic>P =</italic> 0.28</td>
</tr>
<tr>
<td valign="top" align="left">&#x000A0;&#x000A0;Ascites</td>
<td valign="top" align="center">4</td>
<td valign="top" align="center">119/2010</td>
<td valign="top" align="center">1.94 [1.20, 3.13]; <italic>P =</italic> 0.007</td>
<td valign="top" align="center">I<sup>2</sup> = 41%; <italic>P =</italic> 0.17</td>
</tr>
<tr>
<td valign="top" align="left">&#x000A0;&#x000A0;Postoperative bleeding</td>
<td valign="top" align="center">3</td>
<td valign="top" align="center">46/1212</td>
<td valign="top" align="center">4.55 [1.15, 17.96]; <italic>P =</italic> 0.03</td>
<td valign="top" align="center">I<sup>2</sup> = 0%; <italic>P =</italic> 0.44</td>
</tr>
<tr>
<td valign="top" align="left">&#x000A0;&#x000A0;Short&#x02013;term death</td>
<td valign="top" align="center">5</td>
<td valign="top" align="center">277/3099</td>
<td valign="top" align="center">2.28 [1.15, 4.53]; <italic>P =</italic> 0.02</td>
<td valign="top" align="center">I<sup>2</sup> = 13%; <italic>P =</italic> 0.33</td>
</tr>
</tbody>
</table>
<table-wrap-foot>
<p><italic>CKD, chronic kidney disease</italic>.</p>
</table-wrap-foot>
</table-wrap></sec>
<sec>
<title>Surgery-Related Information</title>
<p>The surgery-related information included blood loss, blood transfusion, and hospital stay. After pooling all the data, the CKD group had larger blood loss (MD = &#x02212;404.79, 95% CI = &#x02212;509.7 to &#x02212;299.88, <italic>P</italic> &#x0003C; 0.00001) and a higher rate of blood transfusion (OR = 2.47, 95% CI = 1.85 to 3.3, <italic>P</italic> &#x0003C; 0.00001). However, no significant difference was found between the CKD group and the non-CKD group (MD = 4.07, 95% CI = &#x02212;5.52 to 13.67, <italic>P</italic> = 0.41).</p></sec>
<sec>
<title>Postoperative Complications</title>
<p>Seven studies reported postoperative complications, and after pooling the data, the CKD group had a higher rate of overall complications (OR = 2.1, 95% CI = 1.57 to 2.81, <italic>P</italic> &#x0003C; 0.00001) (<xref ref-type="fig" rid="F2">Figure 2A</xref>). In terms of &#x02265; grade III complications, the CKD group had a higher rate of &#x02265; grade III complications as well (OR = 2.04, 95% CI = 1.57 to 2.81, <italic>P</italic> = 0.0002) (<xref ref-type="fig" rid="F2">Figure 2B</xref>).</p>
<fig id="F2" position="float">
<label>Figure 2</label>
<caption><p>Complications between the chronic kidney disease (CKD) group and the non-CKD group. <bold>(A)</bold> Overall complications; <bold>(B)</bold> &#x02265; grade III complications.</p></caption>
<graphic mimetype="image" mime-subtype="tiff" xlink:href="fsurg-09-870946-g0002.tif"/>
</fig>
<p>As for specific complications, the CKD group had a higher rate of surgical site infection (OR = 2.04, 95% CI = 1.57 to 2.81, <italic>P</italic> = 0.0002), pleural effusion (OR = 2.04, 95% CI = 1.57 to 2.81, <italic>P</italic> = 0.0002), ascites (OR = 2.04, 95% CI = 1.57 to 2.81, <italic>P</italic> = 0.0002), postoperative bleeding (OR = 2.04, 95% CI = 1.57 to 2.81, <italic>P</italic> = 0.0002), and short-term death (OR = 2.04, 95% CI = 1.57 to 2.81, <italic>P</italic> = 0.0002) (<xref ref-type="table" rid="T2">Table 2</xref>).</p></sec>
<sec>
<title>Overall Survival</title>
<p>All the nine studies reported OS between the CKD group and the non-CKD group, and the CKD group had poor OS compared with the non-CKD group (HR = 1.28, 95% CI = 1.1 to 1.49, <italic>P</italic> = 0.001) (<xref ref-type="fig" rid="F3">Figure 3A</xref>). However, in terms of DFS, no significant difference was found between the CKD group and the non-CKD group (HR = 1.11, 95% CI = 0.96 to 1.28, <italic>P</italic> = 0.16) (<xref ref-type="fig" rid="F3">Figure 3B</xref>).</p>
<fig id="F3" position="float">
<label>Figure 3</label>
<caption><p>Survival analysis between the CKD group and the non-CKD group. <bold>(A)</bold> Overall survival; <bold>(B)</bold> disease-free survival.</p></caption>
<graphic mimetype="image" mime-subtype="tiff" xlink:href="fsurg-09-870946-g0003.tif"/>
</fig></sec>
<sec>
<title>Sensitivity Analysis and Publication Bias</title>
<p>Sensitive analysis was conducted by excluding one study in turns, and the results remained the same after excluding one study in turns. Publication bias was determined according to a funnel plot; the funnel plot was symmetrical visually (<xref ref-type="fig" rid="F4">Figure 4</xref>).</p>
<fig id="F4" position="float">
<label>Figure 4</label>
<caption><p>Funnel plot of overall survival.</p></caption>
<graphic mimetype="image" mime-subtype="tiff" xlink:href="fsurg-09-870946-g0004.tif"/>
</fig></sec></sec>
<sec sec-type="discussion" id="s4">
<title>Discussion</title>
<p>A total of nine studies with 6,541 patients were included in this meta-analysis. After pooling all the baseline information, the CKD group had a higher rate of Child-Pugh grade B than the non-CKD group. As for the surgery-related information, the CKD group had larger blood loss and a higher rate of blood transfusion. In terms of complications, the CKD group had a higher rate of overall complications and a higher rate of &#x02265; grade III complications. The CKD group had poor OS compared with the non-CKD group; however, in terms of DFS, no significant difference was found.</p>
<p>As previously described, CKD has a certain impact on a variety of operations, including gastric cancer surgery (<xref ref-type="bibr" rid="B27">27</xref>), colorectal cancer surgery (<xref ref-type="bibr" rid="B28">28</xref>) and bladder cancer surgery (<xref ref-type="bibr" rid="B29">29</xref>). CKD could result in increased complications and reduced OS. However, in terms of liver resection for HCC, it remains controversial whether preexisting CKD has an impact on the complications and prognosis (<xref ref-type="bibr" rid="B13">13</xref>&#x02013;<xref ref-type="bibr" rid="B16">16</xref>). Therefore, it is necessary for surgeons to explore whether there is a precise effect of CKD on liver resection for HCC.</p>
<p>In this meta-analysis, we found that postoperative complications were higher in the CKD group than in the non-CKD group. As for specific complications, we found that patients with CKD required more blood transfusions, and that the proportion of postoperative ascites was increased. The possible reason is that patients with CKD often suffer from other serious comorbidities, including diabetes and cardiovascular disease, which might inhibit wound repair and result in complications (<xref ref-type="bibr" rid="B15">15</xref>). In addition, because of nutritional deficiencies, loss of serum immune system components, and lymphocyte suppression, patients with CKD are in an immunosuppressive state; therefore, they might be more likely to suffer from postoperative infections and even death (<xref ref-type="bibr" rid="B30">30</xref>, <xref ref-type="bibr" rid="B31">31</xref>).</p>
<p>There are many factors that could affect the prognosis after liver resection for HCC including presence of vascular penetration, satellite nodules, tumor differentiation, hepatitis, cirrhosis, and tumor staging (<xref ref-type="bibr" rid="B32">32</xref>, <xref ref-type="bibr" rid="B33">33</xref>). In this meta-analysis, the CKD group had poor OS compared with the non-CKD group; however, in terms of DFS, no significant difference was found. The main reason was related to cardiovascular diseases. Patients with CKD had a higher risk of vascular disease and risk of events such as heart failure, myocardial infarction, stroke, atrial fibrillation, and peripheral arterial, after surgery (<xref ref-type="bibr" rid="B14">14</xref>, <xref ref-type="bibr" rid="B15">15</xref>). Theses cardiovascular diseases might decrease OS. However, as for DFS, the main cause was the tumor itself; therefore, no significant difference was found.</p>
<p>Therefore, when patients with concurrent CKD and HCC are admitted to a hospital, examination of the progression of CKD is necessary. In addition, biological parameters including the immune system components and lymphocyte examination must be tested. For surgeons, it is important to reduce surgical time and give more attention to perioperative management.</p>
<p>There were some important data that were insufficient for meta-analysis and were presented in the included studies. Shirata et al. (<xref ref-type="bibr" rid="B24">24</xref>) reported that the CKD group had no effect on patients with Child-Pugh A liver function compared to the non-CKD group, and that poor OS was identified in patients with concurrent CKD and Child-Pugh B liver function. Hsu et al. (<xref ref-type="bibr" rid="B13">13</xref>) reported that CKD could result in a poor outcome of patients who underwent TACE. Another study did propensity score matching (PSM) and found that the CKD group had poor prognosis, (<xref ref-type="bibr" rid="B23">23</xref>) the baseline information had no significant difference after the PSM, and more studies with the PSM method were needed in the future.</p>
<p>There were some limitations that existed in this meta-analysis. First, only nine retrospective studies were included in this study, which was relatively small. Second, countries of the included studies were restricted to China and Japan; therefore, the results could only be applied to eastern Asians. Third, the definition of CKD group and non-CKD group was different, which might result in heterogeneity. Fourth, the included studies ranged from 20 years ago to now. Improvements in primary postoperative care of the patients during these two decades might have reduced mortality and morbidity; thus, bias might occur. Therefore, multicenter, high-quality randomized controlled trials should be performed in the future.</p>
<p>In conclusion, preexisting CKD was associated with higher ratio of complications and poor OS. However, no difference was found in terms of DFS.</p></sec>
<sec sec-type="data-availability" id="s5">
<title>Data Availability Statement</title>
<p>The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.</p></sec>
<sec id="s6">
<title>Ethics Statement</title>
<p>Ethical review and approval was not required for the study on human participants in accordance with the local legislation and institutional requirements. The patients/participants provided their written informed consent to participate in this study.</p></sec>
<sec id="s7">
<title>Author Contributions</title>
<p>X-YL and Z-QZ: data extraction. C-YW: quality assessments. C-YW and X-YL: data analysis and writing (original draft). C-YW, X-YL, Z-QZ, Y-XC, WT, BZ, and CY: writing (review and editing). All authors read and approved the final version of the manuscript.</p></sec>
<sec sec-type="COI-statement" id="conf1">
<title>Conflict of Interest</title>
<p>The 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></sec>
<sec sec-type="disclaimer" id="s8">
<title>Publisher&#x00027;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>
</body>
<back>
<ack><p>We acknowledge all the authors whose publications are referenced in this article.</p>
</ack>
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