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<front>
<journal-meta>
<journal-id journal-id-type="publisher-id">Front. Endocrinol.</journal-id>
<journal-title-group>
<journal-title>Frontiers in Endocrinology</journal-title>
<abbrev-journal-title abbrev-type="pubmed">Front. Endocrinol.</abbrev-journal-title>
</journal-title-group>
<issn pub-type="epub">1664-2392</issn>
<publisher>
<publisher-name>Frontiers Media S.A.</publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.3389/fendo.2026.1768327</article-id>
<article-version article-version-type="Version of Record" vocab="NISO-RP-8-2008"/>
<article-categories>
<subj-group subj-group-type="heading">
<subject>Systematic Review</subject>
</subj-group>
</article-categories>
<title-group>
<article-title>Comparative analysis of bone density measurement techniques: a systematic review of quantitative ultrasound and dual-energy X-ray absorptiometry</article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author" corresp="yes">
<name><surname>Hadadi</surname><given-names>Ibrahim</given-names></name>
<xref ref-type="corresp" rid="c001"><sup>*</sup></xref>
<uri xlink:href="https://loop.frontiersin.org/people/3317595/overview"/>
<role vocab="credit" vocab-identifier="https://credit.niso.org/" vocab-term="conceptualization" vocab-term-identifier="https://credit.niso.org/contributor-roles/conceptualization/">Conceptualization</role>
<role vocab="credit" vocab-identifier="https://credit.niso.org/" vocab-term="Data curation" vocab-term-identifier="https://credit.niso.org/contributor-roles/data-curation/">Data curation</role>
<role vocab="credit" vocab-identifier="https://credit.niso.org/" vocab-term="Formal analysis" vocab-term-identifier="https://credit.niso.org/contributor-roles/formal-analysis/">Formal analysis</role>
<role vocab="credit" vocab-identifier="https://credit.niso.org/" vocab-term="Funding acquisition" vocab-term-identifier="https://credit.niso.org/contributor-roles/funding-acquisition/">Funding acquisition</role>
<role vocab="credit" vocab-identifier="https://credit.niso.org/" vocab-term="investigation" vocab-term-identifier="https://credit.niso.org/contributor-roles/investigation/">Investigation</role>
<role vocab="credit" vocab-identifier="https://credit.niso.org/" vocab-term="methodology" vocab-term-identifier="https://credit.niso.org/contributor-roles/methodology/">Methodology</role>
<role vocab="credit" vocab-identifier="https://credit.niso.org/" vocab-term="Project-administration" vocab-term-identifier="https://credit.niso.org/contributor-roles/project-administration/">Project administration</role>
<role vocab="credit" vocab-identifier="https://credit.niso.org/" vocab-term="resources" vocab-term-identifier="https://credit.niso.org/contributor-roles/resources/">Resources</role>
<role vocab="credit" vocab-identifier="https://credit.niso.org/" vocab-term="software" vocab-term-identifier="https://credit.niso.org/contributor-roles/software/">Software</role>
<role vocab="credit" vocab-identifier="https://credit.niso.org/" vocab-term="supervision" vocab-term-identifier="https://credit.niso.org/contributor-roles/supervision/">Supervision</role>
<role vocab="credit" vocab-identifier="https://credit.niso.org/" vocab-term="validation" vocab-term-identifier="https://credit.niso.org/contributor-roles/validation/">Validation</role>
<role vocab="credit" vocab-identifier="https://credit.niso.org/" vocab-term="visualization" vocab-term-identifier="https://credit.niso.org/contributor-roles/visualization/">Visualization</role>
<role vocab="credit" vocab-identifier="https://credit.niso.org/" vocab-term="Writing &#x2013; original draft" vocab-term-identifier="https://credit.niso.org/contributor-roles/writing-original-draft/">Writing &#x2013; original draft</role>
<role vocab="credit" vocab-identifier="https://credit.niso.org/" vocab-term="Writing &#x2013; review &amp; editing" vocab-term-identifier="https://credit.niso.org/contributor-roles/writing-review-editing/">Writing &#x2013; review &amp; editing</role>
</contrib>
</contrib-group>
<aff id="aff1"><institution>Department of Radiological Sciences, College of Applied Medical Sciences, King Khalid University</institution>, <city>Abha</city>,&#xa0;<country country="sa">Saudi Arabia</country></aff>
<author-notes>
<corresp id="c001"><label>*</label>Correspondence: Ibrahim Hadadi, <email xlink:href="mailto:ihadadi@kku.edu.sa">ihadadi@kku.edu.sa</email></corresp>
</author-notes>
<pub-date publication-format="electronic" date-type="pub" iso-8601-date="2026-03-04">
<day>04</day>
<month>03</month>
<year>2026</year>
</pub-date>
<pub-date publication-format="electronic" date-type="collection">
<year>2026</year>
</pub-date>
<volume>17</volume>
<elocation-id>1768327</elocation-id>
<history>
<date date-type="received">
<day>29</day>
<month>12</month>
<year>2025</year>
</date>
<date date-type="accepted">
<day>09</day>
<month>02</month>
<year>2026</year>
</date>
<date date-type="rev-recd">
<day>06</day>
<month>02</month>
<year>2026</year>
</date>
</history>
<permissions>
<copyright-statement>Copyright &#xa9; 2026 Hadadi.</copyright-statement>
<copyright-year>2026</copyright-year>
<copyright-holder>Hadadi</copyright-holder>
<license>
<ali:license_ref start_date="2026-03-04">https://creativecommons.org/licenses/by/4.0/</ali:license_ref>
<license-p>This is an open-access article distributed under the terms of the <ext-link ext-link-type="uri" xlink:href="https://creativecommons.org/licenses/by/4.0/">Creative Commons Attribution License (CC BY)</ext-link>. 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.</license-p>
</license>
</permissions>
<abstract>
<sec>
<title>Background</title>
<p>Bone mineral density (BMD) and bone-related parameters are essential for osteoporosis detection. Different screening modalities are used, including quantitative ultrasound (QUS) and dual-energy X-ray absorptiometry (DXA). This systematic review aimed to evaluate the correlation and clinical utility of DXA and QUS measurements.</p>
</sec>
<sec>
<title>Methods</title>
<p>A literature search (2005&#x2013;2025) was conducted in PubMed, Scopus, Web of Science, EMBASE, Google Scholar, and Cochrane Library for English-language studies. A narrative synthesis was performed to summarize the study characteristics and outcomes.</p>
</sec>
<sec>
<title>Results</title>
<p>Of the 1,247 identified records, 24 studies met the inclusion criteria. DXA and QUS were used to assess bone parameters, such as BMD, bone mineral content (BMC), speed of sound (SOS), broadband ultrasound attenuation (BAU), and stiffness index (SI). The correlation between DXA and QUS varied widely (r = 0.17&#x2013;0.86), with variable diagnostic performance across studies. Studies involving postmenopausal women and older populations reported similar trends, whereas the findings were inconsistent in pediatric and disease-specific populations.</p>
</sec>
<sec>
<title>Conclusion</title>
<p>QUS is suitable for preliminary screening, especially in resource-limited settings, but cannot replace DXA for definitive diagnosis. Further well-designed studies with longer follow-up are required to better define the role of QUS in osteoporosis screening.</p>
</sec>
<sec>
<title>Systematic Review Registration</title>
<p><ext-link ext-link-type="uri" xlink:href="https://www.crd.york.ac.uk/prospero/">https://www.crd.york.ac.uk/prospero/</ext-link>, identifier CRD420251146250.</p>
</sec>
</abstract>
<kwd-group>
<kwd>bone mineral content</kwd>
<kwd>bone mineral density</kwd>
<kwd>bone quality</kwd>
<kwd>DXA</kwd>
<kwd>fractures</kwd>
<kwd>osteoporosis</kwd>
<kwd>QUS</kwd>
</kwd-group>
<funding-group>
<funding-statement>The author(s) declared that financial support was not received for this work and/or its publication.</funding-statement>
</funding-group>
<counts>
<fig-count count="1"/>
<table-count count="6"/>
<equation-count count="0"/>
<ref-count count="49"/>
<page-count count="15"/>
<word-count count="6142"/>
</counts>
<custom-meta-group>
<custom-meta>
<meta-name>section-at-acceptance</meta-name>
<meta-value>Bone Research</meta-value>
</custom-meta>
</custom-meta-group>
</article-meta>
</front>
<body>
<sec id="s1" sec-type="intro">
<label>1</label>
<title>Introduction</title>
<p>Osteoporosis is characterized by a progressive decline in bone mineral density (BMD) and deterioration of the bone microarchitecture, which substantially increases skeletal fragility (<xref ref-type="bibr" rid="B1">1</xref>, <xref ref-type="bibr" rid="B2">2</xref>). Often remaining asymptomatic until the occurrence of a fragility fracture, the condition is frequently underdiagnosed, despite its significant global health impact. Such fractures account for millions of new clinical cases annually and are a primary driver of increased morbidity and mortality in aging populations (<xref ref-type="bibr" rid="B3">3</xref>&#x2013;<xref ref-type="bibr" rid="B5">5</xref>).</p>
<p>Although the World Health Organization (WHO) diagnostic criteria for osteoporosis remain centered on BMD T-scores measured at clinically relevant skeletal sites, the clinical application of these standards relies heavily on Dual-energy X-ray absorptiometry (DXA) (<xref ref-type="bibr" rid="B6">6</xref>). Currently, the reference standard, DXA, is favored for its reproducibility and low radiation exposure (<xref ref-type="bibr" rid="B7">7</xref>, <xref ref-type="bibr" rid="B8">8</xref>). However, DXA measurements may be affected by technical and procedural factors, including patient positioning and analysis protocols, and its availability is largely restricted to hospital-based settings (<xref ref-type="bibr" rid="B8">8</xref>).</p>
<p>A significant limitation of DXA is its reliance on two-dimensional areal density, which does not account for bone volume. Consequently, larger bones may yield artificially inflated BMD values compared to smaller bones with identical volumetric densities, potentially leading to diagnostic inaccuracies based solely on bone size (<xref ref-type="bibr" rid="B9">9</xref>). Furthermore, it is largely confined to hospitals and remains poorly suited for bedside screening or use in rural and community settings. Quantitative ultrasound (QUS) has emerged as a viable non-invasive, portable, and radiation-free alternative, to DXA offering the portability required for broader clinical and community-based applications. Its parameters include broadband ultrasound attenuation (BUA), speed of sound (SOS), and stiffness index (SI) (<xref ref-type="bibr" rid="B10">10</xref>). QUS is usually used for easily accessible bones, such as the calcaneus, tibia, patella, metatarsal bones, phalanges, and radius (<xref ref-type="bibr" rid="B11">11</xref>). Large population-based datasets, including the UK Biobank, have further supported the use of QUS-derived estimates of bone status in epidemiological and genetic studies (<xref ref-type="bibr" rid="B12">12</xref>). Both DXA and QUS are associated with fracture risk prediction, particularly for hip fractures in older populations. However, established clinical guidelines emphasize that QUS should serve as a pre-screening tool to identify individuals who may benefit from confirmatory DXA assessment, rather than as a replacement for the reference standard (<xref ref-type="bibr" rid="B13">13</xref>, <xref ref-type="bibr" rid="B14">14</xref>).</p>
<p>Although QUS has been expanded for clinical adoption, its performance relative to DXA remains inconsistent across different populations and devices. These discrepancies in the literature are often rooted in the heterogeneity of QUS technologies, differing skeletal measurement sites, and varying definitions of outcomes. Beyond fracture risk prediction, the degree of clinical interchangeability between these modalities remains contentious. This systematic review investigates these correlations to clarify the clinical utility of QUS and to define its specific role within established osteoporosis screening frameworks.</p>
</sec>
<sec id="s2">
<label>2</label>
<title>Methodology</title>
<p>This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, with a completed PRISMA checklist provided as a Supplementary File (<xref ref-type="bibr" rid="B15">15</xref>). The study protocol was registered in the International Prospective Register of Systematic Reviews (PROSPERO) under the registration number CRD420251146250 on 12 September 2025. The registration process was retrospective. No amendments were made to the protocol after registration.</p>
<sec id="s2_1">
<label>2.1</label>
<title>Search strategy</title>
<p>For the selection of studies, the PICO framework was used: P (Population): Patents scanned for bone density measurement, I (Intervention): QUS used for scanning, C (Comparator): DXA used for comparison, O (Outcomes): Bone density measurements, including BMD, which reflects the mineral concentration/unit area, BMC quantifies the total mineral amount in a bone region, SOS reflects bone density and elasticity, BUA measures the reduction in the ultrasound signal when it passes through bone, SI is the combination of SOS and BUA, diagnostic accuracy and precision, correlation, and clinical outcomes. These parameters were selected because they represent both the structural and functional aspects of bone health. The literature search was conducted in PubMed, Scopus, Web of Science, EMBASE, Google Scholar, and Cochrane Library. The search covered publications from January 2005 to July 2025. The search terms were strategically combined using Boolean operators and included variations of the key concepts (<xref ref-type="table" rid="T1"><bold>Table&#xa0;1</bold></xref>).</p>
<table-wrap id="T1" position="float">
<label>Table&#xa0;1</label>
<caption>
<p>Search terms and their combinations to search relevant literature.</p>
</caption>
<table frame="hsides">
<thead>
<tr>
<th valign="middle" align="left">Category</th>
<th valign="middle" align="left">Search terms</th>
</tr>
</thead>
<tbody>
<tr>
<td valign="middle" align="left">Primary measurement techniques</td>
<td valign="middle" align="left">&#x201c;quantitative ultrasound,&#x201d; OR &#x201c;QUS,&#x201d; OR &#x201c;dual-energy X-ray absorptiometry,&#x201d; OR &#x201c;DXA,&#x201d; OR &#x201c;DEXA&#x201d;</td>
</tr>
<tr>
<td valign="middle" align="left">Clinical parameters</td>
<td valign="middle" align="left">&#x201c;bone density,&#x201d; OR &#x201c;bone mineral density,&#x201d; OR &#x201c;BMD,&#x201d; OR &#x201c;osteoporosis diagnosis&#x201d;</td>
</tr>
<tr>
<td valign="middle" align="left">Study types</td>
<td valign="middle" align="left">&#x201c;comparative studies,&#x201d; OR &#x201c;validation studies,&#x201d; OR &#x201c;clinical trials&#x201d;</td>
</tr>
<tr>
<td valign="middle" align="left">Population terms</td>
<td valign="middle" align="left">&#x201c;postmenopausal,&#x201d; OR &#x201c;elderly,&#x201d; OR &#x201c;adult,&#x201d; &#x201c;children,&#x201d; OR &#x201c;diabetic&#x201d;</td>
</tr>
<tr>
<td valign="middle" align="left">Outcome</td>
<td valign="middle" align="left">&#x201c;correlation&#x201d; OR &#x201c;accuracy,&#x201d; OR &#x201c;precision,&#x201d; OR &#x201c;sensitivity,&#x201d; &#x201c;specificity&#x201d;</td>
</tr>
<tr>
<td valign="middle" align="left">Final Search String</td>
<td valign="middle" align="left">(1&#x2003;AND 2 AND 3 AND 4 AND 5)</td>
</tr>
</tbody>
</table>
</table-wrap>
</sec>
<sec id="s2_2">
<label>2.2</label>
<title>Inclusion and exclusion criteria</title>
<p>Studies were eligible if they were comparative and analyzed the two modalities of bone density assessment. In terms of outcomes, the primary outcome was direct comparison of bone density measurements, with secondary&#x2002;outcomes including diagnostic accuracy and precision, correlation between techniques, and clinical outcomes, where possible with clear reporting around measuring protocols. Studies published between January 2005 and July 2025 in English language and peer-reviewed journals.</p>
<p>Studies that did&#x2002;not compare the two modalities with accuracy and precision outcomes were excluded. In addition, case reports, reviews, commentaries, animal studies, non-English publications, conference abstracts without full texts, letters to the editor, and opinion&#x2002;pieces were excluded. Exclusion criteria were also applied on technical grounds, including obsolete technology, non-standard protocols, lack of&#x2002;description of methodology, absence of statistical analysis, and insufficient quality control, among others.</p>
</sec>
<sec id="s2_3">
<label>2.3</label>
<title>Studies selection process</title>
<p>Studies were initially identified through searches of multiple databases, and duplicate records were excluded. The titles and abstracts of the retrieved records were screened by the author according to predefined inclusion and exclusion criteria. Full-text articles of potentially relevant studies were subsequently retrieved and assessed for eligibility by the author. Eligibility criteria were uniformly applied across all screening stages to ensure consistency in study selection. Studies excluded at the full-text stage were documented, along with the reasons for exclusion. All studies meeting the eligibility criteria were included in this systematic review for qualitative synthesis.</p>
</sec>
<sec id="s2_4">
<label>2.4</label>
<title>Data extraction process</title>
<p>Four areas were covered in the extraction process. Study characteristics were extracted first, including the author, year of publication, study design, methodology, sample size, population characteristics, study geographical location, and setting. Second, technical parameters were&#x2002;recorded, including the measurement protocols for each modality, equipment specifications and calibration methodologies, quality control procedures, and information on the measurement sites and parameters. Third, outcome data obtained (i.e., the number of&#x2002;participants meeting defined primary and secondary outcomes, estimates of statistical analyses performed, correlation coefficients, and diagnostic accuracy measures). Finally, quality indicators were evaluated to assess the strength of the study design, statistical handling, control of confounders, and completeness of follow-up.</p>
</sec>
<sec id="s2_5">
<label>2.5</label>
<title>Definition of study variables</title>
<p>The primary variables of interest included BMD measurements obtained using DXA at clinically relevant skeletal sites and QUS-derived parameters, including BUS, SOS, and SI, as defined in the original studies. The outcome variables included reported measures of association between QUS and DXA, diagnostic performance metrics where available, and fracture-related outcomes. The secondary variables comprised skeletal measurement sites, participant demographic characteristics, and technical characteristics of the measurement devices, as reported in the included studies.</p>
</sec>
<sec id="s2_6">
<label>2.6</label>
<title>Quality assessment</title>
<p>Standardized evaluation tools relevant to each study design were employed to appraise the&#x2002;methodological quality of the included studies. The quality of observational studies was evaluated using the Newcastle&#x2013;Ottawa Scale according to&#x2002;selection, comparability, and outcome assessment. The methodological quality of the <italic>in vitro</italic> studies was assessed using the QUIN assessment tool. This assessment tool comprises items such as aim/objectives, sample size calculation, comparison group, methodology explanation, operator details, randomization, method of measurement of outcomes, outcome assessment or details, blinding, statistical analysis, and presentation of results. Single <italic>in vitro</italic> study was evaluated according to these items and rated as yes (allocating 1&#x2013;2 points), no with 0 points or not applicable, high risk of bias (RoB) scores &lt;50%, 50%&#x2013;70% were the medium RoB, and &gt;70% were the low RoB (<xref ref-type="bibr" rid="B16">16</xref>). These established tools provide a rigorous and objective assessment of the methodological quality of all eligible studies.</p>
</sec>
<sec id="s2_7">
<label>2.7</label>
<title>Certainty of evidence</title>
<p>The Grading, Reporting, Assessment, Development, and Evaluation (GRADE) framework was used to assess the certainty of the evidence. Outcomes were rated in the domain of methodological limitations, indirectness, imprecision, inconsistency, and publication bias as low, high, or not serious.</p>
</sec>
<sec id="s2_8">
<label>2.8</label>
<title>Statistical analysis</title>
<p>Descriptive statistics were used to summarize the study characteristics, population demographics, measurement parameters, and reported outcomes. Given the substantial clinical and methodological heterogeneity across the included studies, no quantitative pooling or meta-analysis was performed. Instead, the findings were synthesized descriptively, with reported associations between QUS and DXA measurements, diagnostic performance metrics, and fracture-related outcomes summarized narratively, as presented in the original studies. Where applicable, results were described according to relevant study characteristics to facilitate a qualitative comparison.</p>
</sec>
</sec>
<sec id="s3" sec-type="results">
<label>3</label>
<title>Results</title>
<sec id="s3_1">
<label>3.1</label>
<title>Study selection and characteristics</title>
<sec id="s3_1_1">
<label>3.1.1</label>
<title>Identification of the included studies</title>
<p>A total of 1,247 records were identified through database searches. Prior to screening, 255 records were removed, including 71 duplicate records, 94 records marked as ineligible by automation tools, and 90 records removed for other reasons. The remaining 992 records were screened based on their titles and abstracts, of which 748 were excluded. Full-text reports were sought for 244 records, of which 53 were not retrieved. The remaining 191 full-text articles were assessed for eligibility, and 167 were excluded for predefined reasons (PICO not followed, n = 85; required outcomes not reported, n = 39; no comparison with DXA, n = 43). Ultimately, 24 studies were included in the qualitative synthesis (<xref ref-type="fig" rid="f1"><bold>Figure&#xa0;1</bold></xref>).</p>
<fig id="f1" position="float">
<label>Figure&#xa0;1</label>
<caption>
<p>PRISMA flow chart showing study selection process.</p>
</caption>
<graphic mimetype="image" mime-subtype="tiff" xlink:href="fendo-17-1768327-g001.tif">
<alt-text content-type="machine-generated">PRISMA flowchart graphic illustrating the study selection process for a systematic review. Records identified from databases totaled one thousand two hundred forty-seven, with two hundred fifty-five removed before screening. Nine hundred ninety-two records were screened, seven hundred forty-eight excluded, one hundred ninety-one reports assessed, and twenty-four studies included, with exclusion reasons given.</alt-text>
</graphic></fig>
</sec>
<sec id="s3_1_2">
<label>3.1.2</label>
<title>Demographic and study population characteristics</title>
<p>A total of 24 studies conducted across multiple countries were included, encompassing populations from Europe, Asia, Africa, and Oceania (<xref ref-type="table" rid="T2"><bold>Table&#xa0;2</bold></xref>). All studies followed non-randomized designs, with the majority employing cross-sectional methodologies (<xref ref-type="bibr" rid="B17">17</xref>&#x2013;<xref ref-type="bibr" rid="B27">27</xref>), followed by retrospective (<xref ref-type="bibr" rid="B28">28</xref>&#x2013;<xref ref-type="bibr" rid="B31">31</xref>), prospective (<xref ref-type="bibr" rid="B32">32</xref>, <xref ref-type="bibr" rid="B33">33</xref>, <xref ref-type="bibr" rid="B40">40</xref>), and longitudinal designs (<xref ref-type="bibr" rid="B34">34</xref>, <xref ref-type="bibr" rid="B35">35</xref>). A single study followed the cohort, validation, <italic>in vitro</italic>, and case-control study designs (<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>Comprehensive narrative analysis (study and participants) of included studies.</p>
</caption>
<table frame="hsides">
<thead>
<tr>
<th valign="middle" colspan="5" align="left">Study characteristics</th>
<th valign="middle" colspan="4" align="left">Participant characteristics</th>
</tr>
<tr>
<th valign="middle" align="left">Study ID</th>
<th valign="middle" align="left">Country</th>
<th valign="middle" align="left">Study design</th>
<th valign="middle" align="left">Sample size</th>
<th valign="middle" align="left">Study settings</th>
<th valign="middle" align="left">Gender (M:F)</th>
<th valign="middle" align="left">Age (Years)</th>
<th valign="middle" align="left">BMI (Kg/m<sup>2</sup>)</th>
<th valign="middle" align="left">Comorbidities</th>
</tr>
</thead>
<tbody>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B19">19</xref>)</td>
<td valign="middle" align="left">Saudi Arabia</td>
<td valign="middle" align="left">Cross-sectional</td>
<td valign="middle" align="left">437 (Osteoporosis, osteopenia, normal)</td>
<td valign="middle" align="left">Primary care clinics, employee health clinic</td>
<td valign="middle" align="left">0:437</td>
<td valign="middle" align="left">47</td>
<td valign="middle" align="left">NA</td>
<td valign="middle" align="left">NA</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B37">37</xref>)</td>
<td valign="middle" align="left">Germany</td>
<td valign="middle" align="left"><italic>In vitro</italic></td>
<td valign="middle" align="left">26 (Cadavers)</td>
<td valign="middle" align="left">Hospital-based</td>
<td valign="middle" align="left">12:14</td>
<td valign="middle" align="left">56&#x2013;96</td>
<td valign="middle" align="left">NA</td>
<td valign="middle" align="left">NA</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B24">24</xref>)</td>
<td valign="middle" align="left">China</td>
<td valign="middle" align="left">Cross-sectional</td>
<td valign="middle" align="left">Postmenopausal with T2DM:76,<break/>Postmenopausal without T2DM:86</td>
<td valign="middle" align="left">Hospital-based</td>
<td valign="middle" align="left">Postmenopausal with T2DM: 0:76,<break/>Postmenopausal without T2DM: 0:86</td>
<td valign="middle" align="left">46&#x2013;83</td>
<td valign="middle" align="left">24.2</td>
<td valign="middle" align="left">Diabetes</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B22">22</xref>)</td>
<td valign="middle" align="left">Greece</td>
<td valign="middle" align="left">Cross-sectional</td>
<td valign="middle" align="left">Severe hemophilia A: 17, moderate hemophilia: 10</td>
<td valign="middle" align="left">Hospital-based</td>
<td valign="middle" align="left">NA</td>
<td valign="middle" align="left">11.75&#x2013;13.19</td>
<td valign="middle" align="left">NA</td>
<td valign="middle" align="left">Hemophilia and one patient with hepatitis C</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B27">27</xref>)</td>
<td valign="middle" align="left">Sweden</td>
<td valign="middle" align="left">Cross-sectional</td>
<td valign="middle" align="left">80 postmenopausal women</td>
<td valign="middle" align="left">Hospital-based</td>
<td valign="middle" align="left">0:80</td>
<td valign="middle" align="left">63</td>
<td valign="middle" align="left">24.6</td>
<td valign="middle" align="left">NA</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B29">29</xref>)</td>
<td valign="middle" align="left">India</td>
<td valign="middle" align="left">Retrospective</td>
<td valign="middle" align="left">101 (Normal, premenopausal, postmenopausal)</td>
<td valign="middle" align="left">University campus</td>
<td valign="middle" align="left">0:101</td>
<td valign="middle" align="left">20&#x2013;65</td>
<td valign="middle" align="left">Normal = 23.47, premenopausal = 26.02, postmenopausal = 26.99</td>
<td valign="middle" align="left">NA</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B39">39</xref>)</td>
<td valign="middle" align="left">Malaysia</td>
<td valign="middle" align="left">Validation study</td>
<td valign="middle" align="left">134 children</td>
<td valign="middle" align="left">Part of SEANUTS</td>
<td valign="middle" align="left">69:65</td>
<td valign="middle" align="left">9.3</td>
<td valign="middle" align="left">Male = 17.7, Female = 17.6</td>
<td valign="middle" align="left">NA</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B38">38</xref>)</td>
<td valign="middle" align="left">Germany</td>
<td valign="middle" align="left">Case-control</td>
<td valign="middle" align="left">Postmenopausal women: 91, Health control: 91</td>
<td valign="middle" align="left">Clinical</td>
<td valign="middle" align="left">Postmenopausal women: 0:91, Health control: 0:91</td>
<td valign="middle" align="left">Postmenopausal women: 78.2, Health control: 75.7</td>
<td valign="middle" align="left">Postmenopausal women: 25.1, Health control: 26.6</td>
<td valign="middle" align="left">NA</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B30">30</xref>)</td>
<td valign="middle" align="left">Thailand</td>
<td valign="middle" align="left">Retrospective</td>
<td valign="middle" align="left">181 children</td>
<td valign="middle" align="left">School-based and part of SEANUTS</td>
<td valign="middle" align="left">90:91</td>
<td valign="middle" align="left">9.1</td>
<td valign="middle" align="left">Male = 17.9, Female = 17</td>
<td valign="middle" align="left">NA</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B20">20</xref>)</td>
<td valign="middle" align="left">Spain</td>
<td valign="middle" align="left">Cross-sectional</td>
<td valign="middle" align="left">107 adolescents</td>
<td valign="middle" align="left">The PRO-BONE Study</td>
<td valign="middle" align="left">107:0</td>
<td valign="middle" align="left">13.2</td>
<td valign="middle" align="left">18.7</td>
<td valign="middle" align="left">NA</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B28">28</xref>)</td>
<td valign="middle" align="left">Nepal</td>
<td valign="middle" align="left">Retrospective</td>
<td valign="middle" align="left">115 (females with menopause)</td>
<td valign="middle" align="left">Hospital-based</td>
<td valign="middle" align="left">50:65</td>
<td valign="middle" align="left">60.17</td>
<td valign="middle" align="left">NA</td>
<td valign="middle" align="left">Diabetes, COPD, hyperthyroidism, rheumatic arthritis, chronic renal failure</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B25">25</xref>)</td>
<td valign="middle" align="left">Ireland</td>
<td valign="middle" align="left">Cross-sectional</td>
<td valign="middle" align="left">56</td>
<td valign="middle" align="left">Hospital-based</td>
<td valign="middle" align="left">43: 13 postmenopausal</td>
<td valign="middle" align="left">58</td>
<td valign="middle" align="left">28.4</td>
<td valign="middle" align="left">NA</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B18">18</xref>)</td>
<td valign="middle" align="left">New Zealand</td>
<td valign="middle" align="left">Cross-sectional</td>
<td valign="middle" align="left">124 children</td>
<td valign="middle" align="left">Human nutrition research unit</td>
<td valign="middle" align="left">58:66</td>
<td valign="middle" align="left">10</td>
<td valign="middle" align="left">18.7</td>
<td valign="middle" align="left">NA</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B34">34</xref>)</td>
<td valign="middle" align="left">Vietnam</td>
<td valign="middle" align="left">Longitudinal</td>
<td valign="middle" align="left">2043</td>
<td valign="middle" align="left">Part of the Vietnam Osteoporosis Study</td>
<td valign="middle" align="left">773:1270</td>
<td valign="middle" align="left">44&#x2013;45.9</td>
<td valign="middle" align="left">Male = 23, Female = 23.4</td>
<td valign="middle" align="left">NA</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B32">32</xref>)</td>
<td valign="middle" align="left">Sweden</td>
<td valign="middle" align="left">Prospective</td>
<td valign="middle" align="left">62 diabetic patients</td>
<td valign="middle" align="left">Foot clinics</td>
<td valign="middle" align="left">34:28</td>
<td valign="middle" align="left">50-65</td>
<td valign="middle" align="left">T1DM = 24,<break/>T2DM = 27</td>
<td valign="middle" align="left">Diabetes</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B31">31</xref>)</td>
<td valign="middle" align="left">Taiwan</td>
<td valign="middle" align="left">Retrospective</td>
<td valign="middle" align="left">772 osteoporotic and non-osteoporotic patients</td>
<td valign="middle" align="left">Hospital-based</td>
<td valign="middle" align="left">352:420</td>
<td valign="middle" align="left">72.9</td>
<td valign="middle" align="left">NA</td>
<td valign="middle" align="left">NA</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B35">35</xref>)</td>
<td valign="middle" align="left">South Africa</td>
<td valign="middle" align="left">Longitudinal</td>
<td valign="middle" align="left">Child with HIV: 80, Child without HIV: 90</td>
<td valign="middle" align="left">Hospital-based</td>
<td valign="middle" align="left">Child with HIV: 40:40, Child without HIV: 51:39</td>
<td valign="middle" align="left">7.14&#x2013;7.29</td>
<td valign="middle" align="left">16.1&#x2013;16.6</td>
<td valign="middle" align="left">HIV</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B33">33</xref>)</td>
<td valign="middle" align="left">China</td>
<td valign="middle" align="left">Prospective</td>
<td valign="middle" align="left">274 (Healthy, osteopenia, Osteoporosis)</td>
<td valign="middle" align="left">Hospital-based</td>
<td valign="middle" align="left">NA</td>
<td valign="middle" align="left">53.78&#x2013;67.11</td>
<td valign="middle" align="left">Health = 24.40, Osteopenia = 23.87, Osteoporosis = 22.75</td>
<td valign="middle" align="left">NA</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B36">36</xref>)</td>
<td valign="middle" align="left">UK</td>
<td valign="middle" align="left">Cohort</td>
<td valign="middle" align="left">216,753</td>
<td valign="middle" align="left">UK-biobank</td>
<td valign="middle" align="left">100,065:116,688</td>
<td valign="middle" align="left">57.8&#x2013;58.7</td>
<td valign="middle" align="left">NA</td>
<td valign="middle" align="left">NA</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B21">21</xref>)</td>
<td valign="middle" align="left">Thailand</td>
<td valign="middle" align="left">Cross-sectional</td>
<td valign="middle" align="left">67</td>
<td valign="middle" align="left">Hospital-based</td>
<td valign="middle" align="left">67:0</td>
<td valign="middle" align="left">&gt;50</td>
<td valign="middle" align="left">NA</td>
<td valign="middle" align="left">COPD</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B26">26</xref>)</td>
<td valign="middle" align="left">India</td>
<td valign="middle" align="left">Cross-sectional</td>
<td valign="middle" align="left">90 (postmenopausal women)</td>
<td valign="middle" align="left">Hospital-based</td>
<td valign="middle" align="left">0:90</td>
<td valign="middle" align="left">55.82</td>
<td valign="middle" align="left">25.40</td>
<td valign="middle" align="left">Back pain</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B40">40</xref>)</td>
<td valign="middle" align="left">Switzerland</td>
<td valign="middle" align="left">Prospective cohort</td>
<td valign="middle" align="left">1345 (postmenopausal women)</td>
<td valign="middle" align="left">Community-based (OsteoLaus cohort)</td>
<td valign="middle" align="left">0:1345</td>
<td valign="middle" align="left">65</td>
<td valign="middle" align="left">NA</td>
<td valign="middle" align="left">NA</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B17">17</xref>)</td>
<td valign="middle" align="left">Italy</td>
<td valign="middle" align="left">Cross-sectional</td>
<td valign="middle" align="left">201 (females were menopausal)</td>
<td valign="middle" align="left">Two Italian centers</td>
<td valign="middle" align="left">11:190</td>
<td valign="middle" align="left">62.1</td>
<td valign="middle" align="left">NA</td>
<td valign="middle" align="left">Rheumatic musculoskeletal disease, CKD, and Diabetes</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B23">23</xref>)</td>
<td valign="middle" align="left">Uganda</td>
<td valign="middle" align="left">Cross-sectional</td>
<td valign="middle" align="left">167</td>
<td valign="middle" align="left">Hospital-based and subtype of the CHAPAS-4 trial</td>
<td valign="middle" align="left">85:82</td>
<td valign="middle" align="left">9.4</td>
<td valign="middle" align="left">NA</td>
<td valign="middle" align="left">HIV</td>
</tr>
</tbody>
</table>
<table-wrap-foot>
<fn>
<p>Age (years) is expressed as mean, SEANUTS, South East Asian Nutrition Surveys; M, Male; F, Female; BMI, Body Mass Index; CKD, Chronic Kidney Disease; COPD, Chronic Obstructive Pulmonary Disease; T1DM, Type 1 Diabetes Mellitus; T2DM, Type 2 Diabetes Mellitus; NA, Not Available.</p></fn>
</table-wrap-foot>
</table-wrap>
<p>The cumulative sample size across all 24 studies (223,676 participants), with individual study populations ranging from 27 to 216,753 participants (<xref ref-type="bibr" rid="B22">22</xref>, <xref ref-type="bibr" rid="B36">36</xref>). Furthermore, 26 cadavers were used to compare the screening techniques (<xref ref-type="bibr" rid="B37">37</xref>). Most studies were hospital-based and conducted as part of larger research cohorts. Variation was also observed in the sex distribution of the included studies. Most studies (14, 58.3%) included mixed populations, while others specifically focused on menopause/postmenopausal females or males or targeted distinct groups such as diabetic patients or elderly individuals (<xref ref-type="bibr" rid="B19">19</xref>&#x2013;<xref ref-type="bibr" rid="B21">21</xref>, <xref ref-type="bibr" rid="B24">24</xref>, <xref ref-type="bibr" rid="B25">25</xref>, <xref ref-type="bibr" rid="B27">27</xref>, <xref ref-type="bibr" rid="B29">29</xref>, <xref ref-type="bibr" rid="B38">38</xref>). The mean age across studies ranged from 7.14 to 96 years (<xref ref-type="bibr" rid="B35">35</xref>, <xref ref-type="bibr" rid="B37">37</xref>), and reported body mass index values ranged from 17 Kg/m<sup>2</sup> to 28.44 Kg/m<sup>2</sup> (<xref ref-type="bibr" rid="B25">25</xref>, <xref ref-type="bibr" rid="B29">29</xref>). The comorbidities are listed in <xref ref-type="table" rid="T2"><bold>Table&#xa0;2</bold></xref>.</p>
</sec>
</sec>
<sec id="s3_2">
<label>3.2</label>
<title>Technical characteristics of screening modalities</title>
<p>Overall, studies have compared DXA and QUS screening modalities and evaluated various bone parameters, including BMD, BMC, SOS, BAU, SI, and fracture rates. Various models of both screening modalities were used. The calibration methods also differed with some studies using manufacturer-supplied phantoms. Quality control procedures, including routine instrument checks, have been reported in some studies. A significant variation was observed in the measurement sites: QUS primarily targeted the calcaneus (heel), tibia, forearm, and radius, whereas DXA focused more on the lumbar spine, femoral neck, total hip, and sometimes the total body (<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>Technical characteristics of QUS and DXA in screening the participants.</p>
</caption>
<table frame="hsides">
<thead>
<tr>
<th valign="middle" rowspan="2" align="center">Study ID</th>
<th valign="middle" colspan="6" align="center">Technical characteristics</th>
</tr>
<tr>
<th valign="middle" align="center">Modalities compared</th>
<th valign="middle" align="center">Protocol measurements</th>
<th valign="middle" align="center">Equipment specification</th>
<th valign="middle" align="center">Calibration</th>
<th valign="middle" align="center">Quality control procedures</th>
<th valign="middle" align="center">Measurement sites</th>
</tr>
</thead>
<tbody>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B19">19</xref>)</td>
<td valign="middle" align="left">DXA vs QUS</td>
<td valign="middle" align="center">DXA: BMD<break/>QUS: SOS, BUA</td>
<td valign="middle" align="center">DXA: PIXI (Lunar GE, Radiation Corporation, Madison, WI USA)<break/>QUS: Hologic (Sahara clinical Bone Sonometer, USA)</td>
<td valign="middle" align="center">References values were provided by manufacturer for comparison</td>
<td valign="middle" align="center">Procedural manuals were used</td>
<td valign="middle" align="left">DXA: Lumbar spine and femoral neck<break/>QUS: Heel</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B37">37</xref>)</td>
<td valign="middle" align="left">QUS vs DXA</td>
<td valign="middle" align="center">DXA and QUS: Structural and mechanical<break/>properties of bone</td>
<td valign="middle" align="center">QUS: DBM Sonic 1200 (IGEA, Carpi, Italy)<break/>DXA: QDR 1000 Hologic densitometer (Waltham, MA, USA)</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="left">Epiphyseal condyle site and meta-diaphyseal site</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B24">24</xref>)</td>
<td valign="middle" align="left">QUS vs DXA</td>
<td valign="middle" align="center">QUS: SOS<break/>DXA: BMD</td>
<td valign="middle" align="center">QUS: Sunlight Omnisense (7000P device) Petach Tikva, Israel<break/>DXA: DXA system (Lunar Prodigy, GE Healthcare, Madison WI)</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">QUS: SOS verification phantom</td>
<td valign="middle" align="left">QUS: Radius, phalanx, tibia<break/>DXA: Lumber spine, total hip, femoral neck</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B22">22</xref>)</td>
<td valign="middle" align="left">QUS vs DXA</td>
<td valign="middle" align="center">QUS: SOS<break/>DXA: BMD</td>
<td valign="middle" align="center">QUS: Sunlight Omnisense (7000P device) Petach Tikva, Israel<break/>DXA: Cronos bone densitometer (DMS, France)</td>
<td valign="middle" align="center">QUS: Manufacturers&#x2019; verification phantom</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="left">QUS: Peripheral bones<break/>DXA: Lumber spine</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B27">27</xref>)</td>
<td valign="middle" align="left">QUS vs DXA</td>
<td valign="middle" align="center">QUS: SOS, BAU<break/>DXA: BMD, BMC</td>
<td valign="middle" align="center">QUS: LUNAR (Achilles, Madison, WI, USA)<break/>DXA: LUNAR (DPX-L, Lunar Radiation Inc., Madison, WI, USA)</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">Using a phantom every day</td>
<td valign="middle" align="left">QUS: Calcaneal<break/>DXA: Lumber spine</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B29">29</xref>)</td>
<td valign="middle" align="left">QUS vs DXA</td>
<td valign="middle" align="center">QUS: SOS<break/>DXA: BMD</td>
<td valign="middle" align="center">QUS: Omnisense cbone densitometer<break/>DXA: Hologic DiscoverycWi</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="left">QUS: Radius and tibia<break/>DXA: Lumbar spine, total hip, and femoral neck</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B39">39</xref>)</td>
<td valign="middle" align="left">QUS vs DXA</td>
<td valign="middle" align="center">QUS: SOS<break/>DXA: BMD</td>
<td valign="middle" align="center">QUS: Commercial device (Omnisense 8000P, Sunlight, Petah Tikva, Israel)<break/>DXA: Hologic QDR Series Model Discovery W S/N 84687 (Hologic Inc., Waltham, MA, USA)</td>
<td valign="middle" align="center">QUS: Verification phantom was used for calibration provided by the manufacturer<break/>DXA: Spine phantom was used for calibration, supplied by the manufacturer</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="left">QUS: SOS<break/>DXA: BMD</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B38">38</xref>)</td>
<td valign="middle" align="left">DXA vs QUS</td>
<td valign="middle" align="center">DXA: BMD<break/>QUS: SOS, BUA</td>
<td valign="middle" align="center">DXA: Prodigy<sup>&#xae;</sup> bone densitometer (GE/Lunar Corporation, Madison, WI, USA<break/>QUS: Achilles (Lunar, Madison, WI), Sahara (Hologic, Waltham, Massachusetts, USA), InSight (Achilles InSight, GE, USA), Omni (BeamMed, Sunlight), DBM Sonic Bone Profiler (Igea, Capri, Italy) and QUS-2 (Metra/Quidel Inc., San Diego, CA, USA) devices</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">DXA: Quality assurance scans were performed on a daily basis<break/>QUS: As per manufacturer guidelines</td>
<td valign="middle" align="left">DXA: lumbar spine (L1-L4) and the hip (femoral neck and total hip)<break/>QUS: Heel</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B30">30</xref>)</td>
<td valign="middle" align="left">QUS vs DXA</td>
<td valign="middle" align="center">QUS: SOS<break/>DXA: BMD</td>
<td valign="middle" align="center">QUS: Sunlight Omnisense, Petah Tikva, Israel (Model 8000P)<break/>DXA: Lunar Prodigy Pro, Madison, WI, USA (program encore 2008 Version 12.30)</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="left">QUS: Non-dominant arm<break/>DXA: Dominant forearm</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B20">20</xref>)</td>
<td valign="middle" align="left">DXA vs QUS</td>
<td valign="middle" align="center">DXA: BMC<break/>QUS: SOS, BUA</td>
<td valign="middle" align="center">DXA: GE Lunar Healthcare Corp, Madison, WI<break/>QUS: Lunar Achilles Insight<break/>(TM Insight; GE Healthcare, Milwaukee, WI)</td>
<td valign="middle" align="center">Lumber spine phantom as recommended by<break/>the manufacturer for both devices</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="left">DXA: Bilateral<break/>proximal femoral neck, and the total body<break/>QUS: Whole body</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B28">28</xref>)</td>
<td valign="middle" align="left">QUS vs DXA</td>
<td valign="middle" align="center">QUS: SOS<break/>DXA: BMD</td>
<td valign="middle" align="center">QUS: Sunlight MiniOmni bone sonometer (BeamMed Ltd., Tel Aviv, Israel)</td>
<td valign="middle" align="center">DXA: Using spine phantom before the measurements</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="left">Radius, left and right femur, spine</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B25">25</xref>)</td>
<td valign="middle" align="left">QUS vs DXA</td>
<td valign="middle" align="center">QUS: SOS, BUA, SI<break/>DXA: BMD</td>
<td valign="middle" align="center">QUS: General healthcare Lunar (Achilles InSight Densitometer<break/>DXA: Hologic Horizon scanner</td>
<td valign="middle" align="center">QUS: Daily calibration<break/>DXA: International recommendations were used</td>
<td valign="middle" align="center">DXA: International recommendations were used</td>
<td valign="middle" align="left">QUS: Calcaneus<break/>DXA: Spine, lateral spine, total hip, femoral neck</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B18">18</xref>)</td>
<td valign="middle" align="left">QUS vs DXA</td>
<td valign="middle" align="center">QUS: calcaneal BMD, SOS, BUA and SI<break/>DXA: TBLH, BMC, BMD, body composition</td>
<td valign="middle" align="center">QUS: Sahara Clinical Bone Sonometre (Hologic Inc, USA)<break/>DXA: Hologic QDR Discovery A (Hologic Inc., Bedford, MA, USA) with APEX V. 3.2 software</td>
<td valign="middle" align="center">DXA: Calibration materials were used</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="left">QUS: Calcaneus<break/>DXA: Various sites</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B34">34</xref>)</td>
<td valign="middle" align="left">QUS vs DXA</td>
<td valign="middle" align="center">QUS: BUA<break/>DXA: BMD</td>
<td valign="middle" align="center">QUS: Portable ultrasound (Sahara, Hologic Corp., Bedford, MA, USA)<break/>DXA: Hologic Horizon densitometer (Hologic Corp., Bedford, MA, USA)</td>
<td valign="middle" align="center">DXA: Phantom was used before measurement</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="left">QUS: Calcaneus<break/>DXA: Femoral neck, total hip and lumbar spine</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B32">32</xref>)</td>
<td valign="middle" align="left">QUS vs DXA</td>
<td valign="middle" align="center">Bone density and fractures</td>
<td valign="middle" align="center">QUS: Lunar achilles bone densitometer<break/>DXA: Hologic ZDR-4500A</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="left">QUS: Calcaneus in both feet<break/>DXA: Spine and femoral neck</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B31">31</xref>)</td>
<td valign="middle" align="left">QUS vs DXA</td>
<td valign="middle" align="center">DXA: BDM<break/>QUS: SOS</td>
<td valign="middle" align="center">QUS: a Pegasus device (BeamMed Ltd., Tel Aviv, Israel)</td>
<td valign="middle" align="center">DXA: A spine phantom was used prior to measurements</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="left">Hip and spine</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B35">35</xref>)</td>
<td valign="middle" align="left">QUS vs DXA</td>
<td valign="middle" align="center">QUS: SOS, BUA<break/>DXA: BMD</td>
<td valign="middle" align="center">QUS: Lunar Achilles Insights device (GE Healthcare, Madison, WI, USA)<break/>DXA: Hologic Discover Wi bone Densitometer</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">QUS: Built-in quality assurance test before each use</td>
<td valign="middle" align="left">QUS: Calcaneal<break/>DXA: Lumber spine, whole body, radius</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B33">33</xref>)</td>
<td valign="middle" align="left">QUS vs DXA</td>
<td valign="middle" align="center">DXA: BDM<break/>QUS: SOS</td>
<td valign="middle" align="center">QUS: OSTEOKJ7000+ (Kejin, Nanjing, China) with a multichannel convolutional neural<break/>network processes the raw radiofrequency signal<break/>DXA: Prodigy (GE Healthcare,<break/>Waukesha, WI, USA)</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">DXA: Daily standard procedures were followed</td>
<td valign="middle" align="left">QUS: 1/3 distal radius of non-dominant hand<break/>DXA: femoral neck, hip and lumbar spine L1 L4</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B36">36</xref>)</td>
<td valign="middle" align="left">QUS vs DXA</td>
<td valign="middle" align="center">QUS: SOS, BUA<break/>DXA: BMD</td>
<td valign="middle" align="center">QUS: Sahara Clinical<break/>Sonometer (Hologic, Bedford, Massachusetts)</td>
<td valign="middle" align="center">DXA: Manufacturer&#x2019;s phantom was used</td>
<td valign="middle" align="center">QUS: Using a phantom, as per<break/>manufacturer&#x2019;s instructions<break/>DXA: Daily standard procedures were followed</td>
<td valign="middle" align="left">QUS: Heel<break/>DXA: Total body, lumbar, femur</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B21">21</xref>)</td>
<td valign="middle" align="left">QUS vs DXA</td>
<td valign="middle" align="center">QUS: SOS, BUA<break/>DXA: BMD</td>
<td valign="middle" align="center">QUS: Acoustic Osteo-Screener ultrasound device (AOS-100, Aloka Co., Ltd., Japan)<break/>DXA: Osteosys DXAxum T, OsteoSys, Korea</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="left">QUS: Calcaneus<break/>DXA: Lumber spine, femoral neck</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B26">26</xref>)</td>
<td valign="middle" align="left">QUS vs DXA</td>
<td valign="middle" align="center">BMD</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="left">Neck, lumber, wrist</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B40">40</xref>)</td>
<td valign="middle" align="left">QUS vs DXA</td>
<td valign="middle" align="center">QUS: SI, SOS, BUA<break/>DXA: BMD, TBS</td>
<td valign="middle" align="center">QUS: Achilles Express (GE-Lunar, USA)<break/>DXA: Discovery A System (Hologic Inc., Waltham, MA, USA)</td>
<td valign="middle" align="center">Daily calibration of QUS per manufacturer instructions</td>
<td valign="middle" align="center">QUS and DXA performed by same operator; daily phantom calibration</td>
<td valign="middle" align="left">QUS: Heel (right, or left if right fractured)<break/>DXA: Lumbar spine and hip</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B17">17</xref>)</td>
<td valign="middle" align="left">QUS vs DXA</td>
<td valign="middle" align="center">QUS: SOS, BUA<break/>DXA: BMD</td>
<td valign="middle" align="center">QUS: OsteoSys BeeTLe<break/>DXA: Lunar Prodigy (GE Healthcare, Madison, WI, USA) or Discovery Acclaim (Hologic, Waltham, MA, USA) devices</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">All DXA scanners underwent daily quality control</td>
<td valign="middle" align="left">Femoral, total hip and lumbar spine levels</td>
</tr>
<tr>
<td valign="middle" align="left">(<xref ref-type="bibr" rid="B23">23</xref>)</td>
<td valign="middle" align="left">DXA vs QUS</td>
<td valign="middle" align="center">DXA: BMD<break/>QUS: SOS, BUA, BQI</td>
<td valign="middle" align="center">DXA: DXA Hologic Discovery Wi DXA scanner Hologic Bedford<break/>Inc. Bedford MA, USA)<break/>QUS: SONOST 3000 (Osteosys, Seoul, South Korea)</td>
<td valign="middle" align="center">DXA: The DXA scanner was calibrated daily using a spine phantom and auto air calibration<break/>for the whole body; QUS: The QUS machine was calibrated daily using a phantom<break/>prior to taking the measurements according to the manufacturer&#x2019;s manual</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="left">DXA: Head, lumbar spine; QUS: non-dominant foot<break/>QUS: Calcaneus</td>
</tr>
</tbody>
</table>
<table-wrap-foot>
<fn>
<p>SI, Stiffness inDXA; TBLH, Total body Less Head; BMC, Bone Mineral Content; BMD, Bone Mineral Density; BUA, Broadband Ultrasound Attenuation; SOS, Speed of Sound; BQI, Bone Quality InDXA; DXA, Dual-Energy X-ray Absorptiometry; QUS, Quantitative Ultrasound.</p></fn>
</table-wrap-foot>
</table-wrap>
</sec>
<sec id="s3_3">
<label>3.3</label>
<title>Summary of key findings by modality comparison</title>
<p>Correlation analyses were the most frequently reported statistical approach used to evaluate the associations between DXA and QUS measurements. Reported correlation coefficients ranged from low (r = 0.17) to high (r = 0.86) (<xref ref-type="bibr" rid="B29">29</xref>, <xref ref-type="bibr" rid="B31">31</xref>), with some studies reporting no statistically significant associations (<xref ref-type="bibr" rid="B22">22</xref>, <xref ref-type="bibr" rid="B30">30</xref>). The diagnostic performance was evaluated in a subset of studies using receiver operating characteristic analysis. The area under the curve (AUC) values varied across studies, devices, and populations, as summarized in <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>Key findings of modalities used for screening of bone structures and quality.</p>
</caption>
<table frame="hsides">
<thead>
<tr>
<th valign="middle" rowspan="2" align="center">Study ID</th>
<th valign="middle" colspan="5" align="center">Outcomes</th>
</tr>
<tr>
<th valign="middle" align="center">Statistical analysis performed</th>
<th valign="middle" align="center">Correlation coefficient</th>
<th valign="middle" align="center">Diagnostic accuracy</th>
<th valign="middle" align="center">Follow-up</th>
<th valign="middle" align="center">Conclusion</th>
</tr>
</thead>
<tbody>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B19">19</xref>)</td>
<td valign="middle" align="center">Correlation analysis</td>
<td valign="middle" align="center">Low to moderate (r = 0.43&#x2013;0.64, p = 0.000)</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">QUS may not be used as a screening tool</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B37">37</xref>)</td>
<td valign="middle" align="center">Correlation analysis</td>
<td valign="middle" align="center">QUS significantly correlated with DXA (r = 0.69&#x2013;0.79, p &lt;0.05)</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">QUS is superior for structures</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B24">24</xref>)</td>
<td valign="middle" align="center">Correlation analysis</td>
<td valign="middle" align="center">r = 0.26&#x2013;0.75, p &lt;0.05</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">Measurement did not change in parallel</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B22">22</xref>)</td>
<td valign="middle" align="center">Correlation analysis</td>
<td valign="middle" align="center">No correlation</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">No correlation was observed</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B27">27</xref>)</td>
<td valign="middle" align="center">Correlation analysis and sensitivity</td>
<td valign="middle" align="center">Significant correlation</td>
<td valign="middle" align="center">Mean Sensitivity QUS: 79%<break/>Mean specificity QUS:45%</td>
<td valign="middle" align="center">7 years</td>
<td valign="middle" align="center">QUS is highly correlated with DXA</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B29">29</xref>)</td>
<td valign="middle" align="center">Correlation coefficient</td>
<td valign="middle" align="center">Significant correlation (SOS radius and tibia (r = 0.858 and 0.860)</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">QUS is a sensitive screening tool</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B39">39</xref>)</td>
<td valign="middle" align="center">Correlation analysis, ROC</td>
<td valign="middle" align="center">The mean difference between the two techniques was relatively large<break/>(0.6, p &lt;0.001)</td>
<td valign="middle" align="center">AUC: 0.94</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">Radial QUS and DXA are not comparable</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B38">38</xref>)</td>
<td valign="middle" align="center">AUC</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">DXA: AUC: Femoral neck = 0.69, Total hip = 0.71, Lumber spine = 0.59;<break/>QUS: Achilles = 0.68, Sahara = 0.63, InSight = 0.67, Omni = 0.60, DBM = 0.55 and QUS-2 = 0.51</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">The Sahara, Achilles, and InSight QUS devices showed similar hip fracture discrimination when compared to DXA</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B30">30</xref>)</td>
<td valign="middle" align="center">Correlation</td>
<td valign="middle" align="center">No correlation was observed</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">At radius, the SOS measurements were not appropriate for the assessment of bone quality status</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B20">20</xref>)</td>
<td valign="middle" align="center">Correlation</td>
<td valign="middle" align="center">Fair to good intra-class correlation coefficients of agreement (r = 0.60&#x2013;0.68)<break/>between DXA and QUS</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">QUS and DXA had comparable outcomes</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B28">28</xref>)</td>
<td valign="middle" align="center">Correlation, ROC analysis</td>
<td valign="middle" align="center">Significant correlation</td>
<td valign="middle" align="center">AUC = 0.69</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">QUS is a sensitive screening tool</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B25">25</xref>)</td>
<td valign="middle" align="center">Correlation analysis, AUC</td>
<td valign="middle" align="center">QUS significantly correlate</td>
<td valign="middle" align="center">AUC = 0.77</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">QUS identify patients with osteoporosis</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B18">18</xref>)</td>
<td valign="middle" align="center">Pearson correlation coefficients, linear regression</td>
<td valign="middle" align="center">Positive correlations between QUS and DXA (r = 0.30&#x2013;0.45, P &lt;0.01)</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">Calcaneal QUS and DXA are not interchangeable methods for measuring bone density in children</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B34">34</xref>)</td>
<td valign="middle" align="center">Linear regression model</td>
<td valign="middle" align="center">BUA modestly correlated with lumbar spine BMD (r = 0.34; P &lt;0.0001) and femoral neck BMD (r = 0.35; P &lt;0.0001)</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">QUS BUA is not a reliable method for screening osteoporosis</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B32">32</xref>)</td>
<td valign="middle" align="center">Correlation and logistic regression</td>
<td valign="middle" align="center">Positive correlation</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">10&#x2013;11 years</td>
<td valign="middle" align="center">QUS is an appropriate modality and is used for calcaneus as a fracture risk predictor</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B31">31</xref>)</td>
<td valign="middle" align="center">Correlation analysis, ROC analysis</td>
<td valign="middle" align="center">Low correlation (r = 0.17)</td>
<td valign="middle" align="center">AUC: 0.731</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">A meaningful but low correlation between QUS and DXA</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B35">35</xref>)</td>
<td valign="middle" align="center">Correlation analysis</td>
<td valign="middle" align="center">strong correlations at the calcaneus<break/>but modest at the radius</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">12 months</td>
<td valign="middle" align="center">The two methods did not correlate well longitudinally</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B33">33</xref>)</td>
<td valign="middle" align="center">AUC</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">QUS: Sensitivity = 80.86%, Specificity = 84.23%, Accuracy = 83.05%</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">QUS tools are promising future developmental directions</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B36">36</xref>)</td>
<td valign="middle" align="center">Reliability, correlation and sensitivity</td>
<td valign="middle" align="center">Low to modest correlations<break/>(r = 0.29 to 0.44)</td>
<td valign="middle" align="center">Sensitivity: Very poor (0.05&#x2013;0.23) for osteoporosis, and poor<break/>(0.37&#x2013;0.62) for osteopenia</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">QUS has the potential to produce<break/>reliable absolute BMD measurements</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B21">21</xref>)</td>
<td valign="middle" align="center">Correlation, sensitivity, specificity</td>
<td valign="middle" align="center">Significantly moderate correlation</td>
<td valign="middle" align="center">Sensitivity = 10.4%<break/>Specificity = 94.7%</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">QUS cannot replace DXA as an alternative</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B26">26</xref>)</td>
<td valign="middle" align="center">Correlation analysis, AUC</td>
<td valign="middle" align="center">Significant correlation</td>
<td valign="middle" align="center">Sensitivity = 86.36%<break/>Specificity = 86.76%</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">QUS can be used as an alternative screening tool</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B40">40</xref>)</td>
<td valign="middle" align="center">Correlation and logistic regression analysis</td>
<td valign="middle" align="center">Significant correlation</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">6.7 years</td>
<td valign="middle" align="center">QUS predicts fractures independently of FRAX, BMD, and TBS; suitable as pre-screening tool, not for monitoring</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B17">17</xref>)</td>
<td valign="middle" align="center">Repeatability, ROC analysis</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">QUS: AUC: Femoral neck = 0.81, Total hip = 0.72, Lumber spine = 0.78</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">QUS demonstrated good repeatability and performance similar to DXA</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B23">23</xref>)</td>
<td valign="middle" align="center">Correlation, AUC</td>
<td valign="middle" align="center">Moderate to weak correlation</td>
<td valign="middle" align="center">QUS was a weak predictor of DXA Z-score equal to or less than &#x2212;2 (area under the ROC curve = 0.59)</td>
<td valign="middle" align="center">NA</td>
<td valign="middle" align="center">QUS may not be an appropriate substitute for DXA scan</td>
</tr>
</tbody>
</table>
<table-wrap-foot>
<fn>
<p>BMD, Bone Mineral Density; BUA, Broadband Ultrasound Attenuation; SOS, Speed of Sound; DXA, Dual-Energy X-ray Absorptiometry; QUS, Quantitative Ultrasound; ROC, Receiver Operating Characteristic; AUC, Area Under the Curve; r, correlation coefficient.</p></fn>
</table-wrap-foot>
</table-wrap>
</sec>
<sec id="s3_4">
<label>3.4</label>
<title>Clinical applications and patient-specific outcomes</title>
<sec id="s3_4_1">
<label>3.4.1</label>
<title>Postmenopausal women</title>
<p>Eight studies included postmenopausal women (<xref ref-type="bibr" rid="B17">17</xref>, <xref ref-type="bibr" rid="B24">24</xref>, <xref ref-type="bibr" rid="B25">25</xref>, <xref ref-type="bibr" rid="B27">27</xref>&#x2013;<xref ref-type="bibr" rid="B29">29</xref>, <xref ref-type="bibr" rid="B38">38</xref>, <xref ref-type="bibr" rid="B40">40</xref>). These studies reported correlations between QUS parameters and DXA measurements, as well as sensitivity and repeatability metrics (<xref ref-type="table" rid="T4"><bold>Table&#xa0;4</bold></xref>).</p>
</sec>
<sec id="s3_4_2">
<label>3.4.2</label>
<title>Elderly population</title>
<p>Studies conducted in elderly populations (50&#x2013;96 years) have reported associations between QUS parameters and fracture-related outcomes, including hip fractures, using calcaneal measurements across multiple QUS devices (<xref ref-type="bibr" rid="B25">25</xref>&#x2013;<xref ref-type="bibr" rid="B28">28</xref>, <xref ref-type="bibr" rid="B33">33</xref>, <xref ref-type="bibr" rid="B36">36</xref>, <xref ref-type="bibr" rid="B38">38</xref>). The reported correlation coefficients varied across studies, with some demonstrating low correlations between QUS and DXA (r = 0.17) (<xref ref-type="bibr" rid="B31">31</xref>) (<xref ref-type="table" rid="T4"><bold>Table&#xa0;4</bold></xref>).</p>
</sec>
<sec id="s3_4_3">
<label>3.4.3</label>
<title>Special populations</title>
<p>Studies involving children aged 7.1&#x2013;13.2 years have reported correlations between QUS and DXA measurements ranging from no association to fair correlation (<xref ref-type="bibr" rid="B18">18</xref>, <xref ref-type="bibr" rid="B22">22</xref>, <xref ref-type="bibr" rid="B23">23</xref>, <xref ref-type="bibr" rid="B30">30</xref>, <xref ref-type="bibr" rid="B35">35</xref>, <xref ref-type="bibr" rid="B39">39</xref>). However, one study reported a fair to good correlation (r = 0.60&#x2013;0.80) between QUS and DXA measurements (<xref ref-type="bibr" rid="B20">20</xref>) (<xref ref-type="table" rid="T4"><bold>Table&#xa0;4</bold></xref>).</p>
</sec>
<sec id="s3_4_4">
<label>3.4.4</label>
<title>Disease-specific analysis</title>
<p>Several studies have evaluated disease-specific populations, including patients with diabetes, COPD, rheumatic arthritis, and chronic renal failure. Reported AUC values ranged from 0.69 to 0.81 across different skeletal sites and outcomes (<xref ref-type="bibr" rid="B17">17</xref>, <xref ref-type="bibr" rid="B28">28</xref>). However, other studies have found no comparable outcomes between QUS and DXA in these populations (<xref ref-type="bibr" rid="B21">21</xref>&#x2013;<xref ref-type="bibr" rid="B24">24</xref>, <xref ref-type="bibr" rid="B35">35</xref>) (<xref ref-type="table" rid="T4"><bold>Table&#xa0;4</bold></xref>).</p>
</sec>
</sec>
<sec id="s3_5">
<label>3.5</label>
<title>Quality assessment outcomes</title>
<p>The methodological quality varied across the studies. Most studies demonstrated adequate reporting of the selection and comparability domains, although five studies lacked sufficient descriptions of participant selection (<xref ref-type="bibr" rid="B19">19</xref>, <xref ref-type="bibr" rid="B22">22</xref>, <xref ref-type="bibr" rid="B30">30</xref>, <xref ref-type="bibr" rid="B36">36</xref>, <xref ref-type="bibr" rid="B38">38</xref>). Adequate follow-up was reported in four studies (<xref ref-type="bibr" rid="B27">27</xref>, <xref ref-type="bibr" rid="B32">32</xref>, <xref ref-type="bibr" rid="B35">35</xref>, <xref ref-type="bibr" rid="B38">38</xref>) (<xref ref-type="table" rid="T5"><bold>Table&#xa0;5</bold></xref>). The <italic>in vitro</italic> study demonstrated a low risk of bias across most assessed domains, although sample size justification, randomization, and blinding procedures were not reported (<xref ref-type="bibr" rid="B37">37</xref>).</p>
<table-wrap id="T5" position="float">
<label>Table&#xa0;5</label>
<caption>
<p>Methodological quality assessment.</p>
</caption>
<table frame="hsides">
<thead>
<tr>
<th valign="middle" rowspan="2" align="center">Study ID</th>
<th valign="middle" align="center">Study design</th>
<th valign="middle" colspan="4" align="center">Selection</th>
<th valign="middle" align="center">Comparability</th>
<th valign="middle" colspan="3" align="center">Outcomes</th>
</tr>
<tr>
<th valign="middle" align="left"/>
<th valign="middle" align="center">Item 1</th>
<th valign="middle" align="center">Item 2</th>
<th valign="middle" align="center">Item 3</th>
<th valign="middle" align="center">Item 4</th>
<th valign="middle" align="center">Item 5</th>
<th valign="middle" align="center">Item 6</th>
<th valign="middle" align="center">Item 7</th>
<th valign="middle" align="center">Item 8</th>
</tr>
</thead>
<tbody>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B19">19</xref>)</td>
<td valign="middle" align="left">Cross-sectional</td>
<td valign="middle" align="left">No description</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">No follow-up</td>
<td valign="middle" align="left">No statement</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B24">24</xref>)</td>
<td valign="middle" align="left">Cross-sectional</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">No follow-up</td>
<td valign="middle" align="left">No statement</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B22">22</xref>)</td>
<td valign="middle" align="left">Cross-sectional</td>
<td valign="middle" align="left">No description</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">No follow-up</td>
<td valign="middle" align="left">No statement</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B27">27</xref>)</td>
<td valign="middle" align="left">Cross-sectional</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">No stated</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B29">29</xref>)</td>
<td valign="middle" align="left">Retrospective</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">No follow-up</td>
<td valign="middle" align="left">No statement</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B39">39</xref>)</td>
<td valign="middle" align="left">Validation study</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">No follow-up</td>
<td valign="middle" align="left">No statement</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B38">38</xref>)</td>
<td valign="middle" align="left">Case-control</td>
<td valign="middle" align="left">No description</td>
<td valign="middle" align="left">Not stated</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B30">30</xref>)</td>
<td valign="middle" align="left">Retrospective</td>
<td valign="middle" align="left">No description</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">No follow-up</td>
<td valign="middle" align="left">No statement</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B20">20</xref>)</td>
<td valign="middle" align="left">Cross-sectional</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">No follow-up</td>
<td valign="middle" align="left">No statement</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B28">28</xref>)</td>
<td valign="middle" align="left">Retrospective</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">No follow-up</td>
<td valign="middle" align="left">No statement</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B25">25</xref>)</td>
<td valign="middle" align="left">Cross-sectional</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">No follow-up</td>
<td valign="middle" align="left">No statement</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B18">18</xref>)</td>
<td valign="middle" align="left">Cross-sectional</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">No follow-up</td>
<td valign="middle" align="left">No statement</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B34">34</xref>)</td>
<td valign="middle" align="left">Longitudinal</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">No follow-up</td>
<td valign="middle" align="left">No statement</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B32">32</xref>)</td>
<td valign="middle" align="left">Prospective</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B31">31</xref>)</td>
<td valign="middle" align="left">Retrospective</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">No follow-up</td>
<td valign="middle" align="left">No statement</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B35">35</xref>)</td>
<td valign="middle" align="left">Longitudinal</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B33">33</xref>)</td>
<td valign="middle" align="left">Prospective</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">No follow-up</td>
<td valign="middle" align="left">No statement</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B36">36</xref>)</td>
<td valign="middle" align="left">Cohort</td>
<td valign="middle" align="left">No description</td>
<td valign="middle" align="left"/>
<td valign="middle" align="left"/>
<td valign="middle" align="left"/>
<td valign="middle" align="left"/>
<td valign="middle" align="left"/>
<td valign="middle" align="left">No follow-up</td>
<td valign="middle" align="left">No statement</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B21">21</xref>)</td>
<td valign="middle" align="left">Cross-sectional</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">No follow-up</td>
<td valign="middle" align="left">No statement</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B26">26</xref>)</td>
<td valign="middle" align="left">Cross-sectional</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">No follow-up</td>
<td valign="middle" align="left">No statement</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B40">40</xref>)</td>
<td valign="middle" align="left">Prospective</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">No statement</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B17">17</xref>)</td>
<td valign="middle" align="left">Cross-sectional</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">No follow-up</td>
<td valign="middle" align="left">No statement</td>
</tr>
<tr>
<td valign="middle" align="center">(<xref ref-type="bibr" rid="B23">23</xref>)</td>
<td valign="middle" align="left">Cross-sectional</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">*</td>
<td valign="middle" align="left">No follow-up</td>
<td valign="middle" align="left">No statement</td>
</tr>
</tbody>
</table>
<table-wrap-foot>
<fn>
<p>Items explanation (Cohort studies): Item 1: Representativeness of participants; Item 2: Selection of non-exposed cohort; Item 3: Ascertainment of exposure; Item 4: Demonstration that outcome of interest was not present at start of study; Item 5: Comparability of cohorts; Item 6: Assessment of outcomes; Item 7: Was follow-up long enough; Item 8: Adequate of follow-up of cohorts. Items explanation (Case-control study): Item 1: Is the case definition adequate; Item 2: Representativeness of the cases; Item 3: Selection of controls; Item 4: Definition of controls; Item 5: Comparability of cases and controls; Item 6: Ascertainment of exposure; Item 7: Same method of ascertainment for cases and controls; Item 8: Non-response rate.</p>
<p>The symbol (*) indicates that the study met the specified criterion for that particular item.</p></fn>
</table-wrap-foot>
</table-wrap>
</sec>
<sec id="s3_6">
<label>3.6</label>
<title>Certainty of evidence</title>
<p>Overall, most studies achieved moderate methodological quality based on the Newcastle-Ottawa Scale, with several cross-sectional and retrospective designs scoring lower in the selection and follow-up domains. Common limitations included incomplete description of participant selection, lack of follow-up, and insufficient reporting of confounder control. Despite these issues, the outcome assessments were generally well reported.</p>
<p>In the methodological limitation domain, no serious concerns were identified, as most studies demonstrated a low risk of bias. Similarly, indirectness was not considered serious because the studies provided sufficient details of patient characteristics, screening modalities, and clinical outcomes. Imprecision was also judged as not serious, as the majority of studies adequately explained patient selection, although five studies did not provide complete details of patient selection. Both positive and negative results were reported across studies; thus, publication bias was not suspected. According to GRADE (<xref ref-type="table" rid="T6"><bold>Table&#xa0;6</bold></xref>), the overall certainty of evidence was rated as low to moderate, with inconsistency in correlation values remaining the main factor limiting confidence in the findings.</p>
<table-wrap id="T6" position="float">
<label>Table&#xa0;6</label>
<caption>
<p>Summary of certainty of evidence using the GRADE framework.</p>
</caption>
<table frame="hsides">
<thead>
<tr>
<th valign="middle" align="left">GRADE domain</th>
<th valign="middle" align="left">Judgement description</th>
<th valign="middle" align="left">Concerns</th>
</tr>
</thead>
<tbody>
<tr>
<td valign="middle" align="left">Methodological limitations</td>
<td valign="middle" align="left">Overall, studies were found with low risk of bias, however, concerns in the selection of patients and follow-up exist (<xref ref-type="table" rid="T5"><bold>Table&#xa0;5</bold></xref>).</td>
<td valign="middle" align="left">Not serious</td>
</tr>
<tr>
<td valign="middle" align="left">Indirectness</td>
<td valign="middle" align="left">Studies provided details of the characteristics of patients, screening modalities, and clinical outcomes (correlation coefficient and ROC).</td>
<td valign="middle" align="left">Not serious</td>
</tr>
<tr>
<td valign="middle" align="left">Imprecision</td>
<td valign="middle" align="left">Overall, acceptable number of patients were included in the selected studies. Most studies clearly define the selection criteria for patients.</td>
<td valign="middle" align="left">Not serious</td>
</tr>
<tr>
<td valign="middle" align="left">Inconsistency</td>
<td valign="middle" align="left">Low to fair correlation was reported.</td>
<td valign="middle" align="left">Not serious</td>
</tr>
<tr>
<td valign="middle" align="left">Publication bias</td>
<td valign="middle" align="left">Even the funnel plot was not constructed for publication bias, however, we did not find any publication bias, as both negative and positive outcomes were reported.</td>
<td valign="middle" align="left">Not suspected</td>
</tr>
</tbody>
</table>
<table-wrap-foot>
<fn>
<p>ROC, Receiver Operating Characteristics.</p></fn>
</table-wrap-foot>
</table-wrap>
</sec>
</sec>
<sec id="s4" sec-type="discussion">
<label>4</label>
<title>Discussion</title>
<p>In this systematic review, QUS demonstrated a low-to-fair correlation with DXA across diverse populations, accompanied by variability in diagnostic accuracy and methodological quality among studies. These findings highlight both the potential and limitations of QUS when considered alongside DXA, particularly in the context of screening rather than diagnosis. The observed heterogeneity across studies underscores the importance of population characteristics, measurement sites, and device-specific factors when interpreting QUS performance.</p>
<p>Our findings are partially consistent with those of Fl&#xf6;ter et&#xa0;al. (<xref ref-type="bibr" rid="B41">41</xref>), who reported the variable diagnostic performance and moderate sensitivity of calcaneal QUS compared with DXA. However, their review was limited to the calcaneus, whereas our analysis included multiple skeletal sites, offering a broader and more comprehensive evaluation of the skeletal sites. Similarly, a meta-analysis by Moayyeri et&#xa0;al. (<xref ref-type="bibr" rid="B42">42</xref>), demonstrated a significant association between heel QUS parameters and fracture risk, although the predictive accuracy was moderate and varied across studies. Importantly, their work focused mainly on fracture prediction rather than diagnostic agreement with DXA, highlighting the complementary role of QUS in relation to DXA.</p>
<p>Evidence from the included studies involving postmenopausal women and older adults suggests that QUS is associated with moderately correlated with DXA and has reported sensitivity values for the detection of low bone density. These findings support the potential role of QUS as a preliminary screening tool in high-risk populations, particularly in settings where access to DXA is limited. Early identification of bone loss in postmenopausal women is clinically relevant because therapeutic interventions become less effective with advancing age (<xref ref-type="bibr" rid="B43">43</xref>). In elderly populations, QUS might help triage individuals who require further DXA evaluation, especially in primary care and low-resource environments (<xref ref-type="bibr" rid="B44">44</xref>, <xref ref-type="bibr" rid="B45">45</xref>).</p>
<p>In pediatric populations, the available evidence indicates a poor agreement between QUS and DXA measurements. Studies investigating children and adolescents have consistently shown weak or inconsistent correlations, suggesting that QUS cannot reliably substitute DXA in younger age groups (<xref ref-type="bibr" rid="B46">46</xref>, <xref ref-type="bibr" rid="B47">47</xref>). Factors such as rapid skeletal growth, anatomical variability, and challenges in standardized measurement sites likely contribute to these findings, thereby limiting the clinical applicability of QUS in pediatric settings.</p>
<p>The findings were particularly inconsistent in patients with chronic conditions, such as diabetes, COPD, and chronic kidney disease. These populations exhibited variable correlations and diagnostic agreement between QUS and DXA, influenced by disease-related alterations in bone metabolism, measurement site selection, and T-score thresholds (<xref ref-type="bibr" rid="B14">14</xref>, <xref ref-type="bibr" rid="B48">48</xref>, <xref ref-type="bibr" rid="B49">49</xref>). These findings indicate that QUS should be used cautiously in clinically complex populations and highlight the need for population-specific calibrations and validations.</p>
<p>Substantial variability in the reported correlations across studies may be attributed to differences in QUS device models, manufacturers, calibration methods, skeletal measurement sites, and operator-dependent factors. These methodological differences limit the comparability across studies and complicate the interpretation of pooled findings.</p>
<p>From a clinical and public health perspective, the findings support the use of QUS as a screening or triage tool rather than a diagnostic replacement for DXA. Its portability, affordability, and lack of ionizing radiation make it particularly attractive for large-scale screening in elderly and postmenopausal populations, especially in low-resource settings. However, confirmatory DXA assessment remains essential for diagnosis and clinical decision-making.</p>
<p>This review provides a comprehensive synthesis of the evidence comparing QUS and DXA across multiple populations and skeletal sites. The strengths of this review include the broad inclusion of study designs and populations and the application of standardized quality and certainty assessment tools. Limitations include the inability to perform a meta-analysis due to substantial heterogeneity, lack of standardized QUS protocols, and variability in outcome definitions and thresholds. Additionally, the overall certainty of the evidence was rated as low to moderate, primarily due to inconsistency and indirectness.</p>
<p>Future studies should focus on standardizing the QUS measurement protocols, device calibration, and diagnostic thresholds. Prospective studies with consistent outcome reporting and longer follow-up are required to better define the role of QUS in fracture risk assessment and screening. Population-specific validation studies, particularly in pediatric and disease-specific cohorts, are essential for improving clinical confidence and applicability.</p>
</sec>
<sec id="s5" sec-type="conclusions">
<label>5</label>
<title>Conclusion</title>
<p>This systematic review summarizes the available evidence comparing QUS and DXA for bone assessment in various populations. The findings indicate that QUS may serve as a preliminary screening tool, particularly in older adults and selected clinical populations, although considerable variability exists across studies. Importantly, the current findings do not support the use of QUS as a substitute for DXA, which remains the diagnostic reference standard for osteoporosis. Further well-designed studies with longer follow-ups and standardized methodologies are required to better define the role of QUS in osteoporosis screening pathways.</p>
</sec>
</body>
<back>
<sec id="s6" sec-type="data-availability">
<title>Data availability statement</title>
<p>Publicly available datasets were analyzed in this study. All data extracted for this review are available from the corresponding author upon reasonable request. No analytical code was generated for this review. All materials used during the review process, including data extraction forms and screening templates, are available upon request.</p></sec>
<sec id="s7" sec-type="author-contributions">
<title>Author contributions</title>
<p>IH: Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing &#x2013; original draft, Writing &#x2013; review &amp; editing.</p></sec>
<sec id="s9" sec-type="COI-statement">
<title>Conflict of interest</title>
<p>The author(s) declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.</p></sec>
<sec id="s10" sec-type="ai-statement">
<title>Generative AI statement</title>
<p>The author(s) declared that generative AI was used in the creation of this manuscript. The author used an AI-based language model (ChatGPT 5.1) solely to assist with English language editing and improving the clarity of some sections of this manuscript; all content was critically reviewed, verified, and approved by the author, who takes full responsibility for the final text.</p>
<p>Any alternative text (alt text) provided alongside figures in this article has been generated by Frontiers with the support of artificial intelligence and reasonable efforts have been made to ensure accuracy, including review by the authors wherever possible. If you identify any issues, please contact us.</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>
<mixed-citation publication-type="journal">
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<p>Edited by: <ext-link ext-link-type="uri" xlink:href="https://loop.frontiersin.org/people/1361846">Fabio Vescini</ext-link>, Azienda Sanitaria Universitaria Integrata di Udine, Italy</p></fn>
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<p>Reviewed by: <ext-link ext-link-type="uri" xlink:href="https://loop.frontiersin.org/people/2993816">S&#xfc;reyya Nur</ext-link>, Mustafa Kemal University, T&#xfc;rkiye</p>
<p><ext-link ext-link-type="uri" xlink:href="https://loop.frontiersin.org/people/3124146">Jes&#xfa;s Endara-Mina</ext-link>, Universidad T&#xe9;cnica Particular de Loja, Ecuador</p></fn>
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