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<front>
<journal-meta>
<journal-id journal-id-type="publisher-id">Front. Cardiovasc. Med.</journal-id>
<journal-title>Frontiers in Cardiovascular Medicine</journal-title>
<abbrev-journal-title abbrev-type="pubmed">Front. Cardiovasc. Med.</abbrev-journal-title>
<issn pub-type="epub">2297-055X</issn>
<publisher>
<publisher-name>Frontiers Media S.A.</publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.3389/fcvm.2024.1403242</article-id>
<article-categories>
<subj-group subj-group-type="heading">
<subject>Cardiovascular Medicine</subject>
<subj-group>
<subject>Systematic Review</subject>
</subj-group>
</subj-group>
</article-categories>
<title-group>
<article-title>Relationship between serum uric acid levels and uric acid lowering therapy with the prognosis of patients with heart failure with preserved ejection fraction: a meta-analysis</article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author"><name><surname>Li</surname><given-names>Linzhi</given-names></name>
<xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
<xref ref-type="aff" rid="aff2"><sup>2</sup></xref>
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</contrib>
<contrib contrib-type="author"><name><surname>Chang</surname><given-names>Ying</given-names></name>
<xref ref-type="aff" rid="aff2"><sup>2</sup></xref>
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<contrib contrib-type="author"><name><surname>Li</surname><given-names>Fei</given-names></name>
<xref ref-type="aff" rid="aff2"><sup>2</sup></xref>
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<contrib contrib-type="author" corresp="yes"><name><surname>Yin</surname><given-names>Yuehui</given-names></name>
<xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
<xref ref-type="corresp" rid="cor1">&#x002A;</xref><uri xlink:href="https://loop.frontiersin.org/people/2692355/overview"/>
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<aff id="aff1"><label><sup>1</sup></label><institution>Department of Cardiology, The Second Affiliated Hospital of Chongqing Medical University</institution>, <addr-line>Chongqing</addr-line>, <country>China</country></aff>
<aff id="aff2"><label><sup>2</sup></label><institution>Department of Geriatrics, Chongqing General Hospital</institution>, <addr-line>Chongqing</addr-line>, <country>China</country></aff>
<author-notes>
<fn fn-type="edited-by"><p><bold>Edited by:</bold> Erberto Carluccio, Heart Failure Unit, Italy</p></fn>
<fn fn-type="edited-by"><p><bold>Reviewed by:</bold> Stefano Coiro, Hospital of Santa Maria della Misericordia in Perugia, Italy</p>
<p>Akito Nakagawa, Nakagawa Clinic, Japan</p></fn>
<corresp id="cor1"><label>&#x002A;</label><bold>Correspondence:</bold> Yuehui Yin <email>yhyincardiology@hotmail.com</email></corresp>
</author-notes>
<pub-date pub-type="epub"><day>13</day><month>06</month><year>2024</year></pub-date>
<pub-date pub-type="collection"><year>2024</year></pub-date>
<volume>11</volume><elocation-id>1403242</elocation-id>
<history>
<date date-type="received"><day>19</day><month>03</month><year>2024</year></date>
<date date-type="accepted"><day>29</day><month>05</month><year>2024</year></date>
</history>
<permissions>
<copyright-statement>&#x00A9; 2024 Li, Chang, Li and Yin.</copyright-statement>
<copyright-year>2024</copyright-year><copyright-holder>Li, Chang, Li and Yin</copyright-holder><license license-type="open-access" xlink:href="http://creativecommons.org/licenses/by/4.0/">
<p>This is an open-access article distributed under the terms of the <ext-link ext-link-type="uri" xlink:href="http://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.</p></license>
</permissions>
<abstract>
<sec><title>Aims</title>
<p>This meta-analysis aimed to explore the association between serum uric acid levels and the efficacy of uric acid-lowering therapies on clinical outcomes among patients with heart failure with preserved ejection fraction (HFpEF).</p>
</sec>
<sec><title>Methods</title>
<p>A comprehensive literature search was conducted through October 21, 2023, across PubMed, Embase, Cochrane Library, and Web of Science databases. The pooled effect sizes were estimated and presented with their respective 95&#x0025; confidence intervals (CI). Subgroup analyses were conducted based on various factors, including sample size (&#x003C;1,000 vs. &#x2265;1,000), follow-up duration (&#x003C;2 years vs. &#x2265;2 years), study quality (assessed by a score of &#x003C;7 vs. &#x2265;7), ethnicity (Non-Asian vs. Asian), study design (prospective vs. retrospective), type of heart failure (HF) (acute vs. chronic), presence of hyperuricemia (yes or no), left ventricular ejection fraction (LVEF) thresholds (&#x2265;45&#x0025; vs. &#x2265;50&#x0025;), and the type of uric acid-lowering therapy (traditional vs. novel).</p>
</sec>
<sec><title>Results</title>
<p>The analysis included a total of 12 studies. Elevated serum uric acid levels were significantly linked to an increased risk of all-cause mortality [relative risk (RR): 1.21, 95&#x0025; CI: 1.06&#x2013;1.37, <italic>P&#x2009;</italic>&#x003D;&#x2009;0.004] and cardiovascular (CV) mortality (RR: 1.71, 95&#x0025; CI: 1.42&#x2013;2.04, <italic>P&#x2009;</italic>&#x003C;&#x2009;0.001) in HFpEF patients. Subgroup analyses confirmed this association, particularly in non-Asian populations, those with chronic HFpEF, and studies with a follow-up duration of two years or more. Additionally, higher uric acid levels were associated with an increased risk of HF-related hospitalization [hazard ratio (HR): 1.61, 95&#x0025; CI: 1.12&#x2013;2.34, <italic>P</italic>&#x2009;&#x003D;&#x2009;0.011]. Regarding treatment, uric acid-lowering therapy did not show a significant effect on reducing mortality in HFpEF patients. However, it was associated with a decreased risk of hospitalization due to HF (RR: 0.85, 95&#x0025; CI: 0.79&#x2013;0.91, <italic>P</italic>&#x2009;&#x003C;&#x2009;0.001).</p>
</sec>
<sec><title>Conclusion</title>
<p>The findings of this study highlight the prognostic significance of serum uric acid levels in HFpEF and suggest that uric acid-lowering therapy may be beneficial in reducing the incidence of HF hospitalizations. Further research is warranted to elucidate the mechanisms by which uric acid-lowering therapy confers its potential benefits.</p>
</sec>
</abstract>
<kwd-group>
<kwd>serum uric</kwd>
<kwd>uric acid lowering therapy</kwd>
<kwd>heart failure with preserved ejection fraction</kwd>
<kwd>meta-analysis</kwd>
<kwd>relationship</kwd>
</kwd-group>
<counts>
<fig-count count="8"/>
<table-count count="4"/><equation-count count="0"/><ref-count count="54"/><page-count count="15"/><word-count count="0"/></counts><custom-meta-wrap><custom-meta><meta-name>section-at-acceptance</meta-name><meta-value>Heart Failure and Transplantation</meta-value></custom-meta></custom-meta-wrap>
</article-meta>
</front>
<body>
<sec id="s1" sec-type="intro"><title>Introduction</title>
<p>Heart failure (HF) is a clinical syndrome resulting from injury and congestion of the heart with a considerable rate of morbidity, mortality, poor functional capacity and quality of life, and high costs (<xref ref-type="bibr" rid="B1">1</xref>). Patients with HF with preserved ejection fraction (HFpEF) [left ventricular ejection fraction (LVEF) &#x2265;50&#x0025;] comprise nearly half of those with chronic HF (<xref ref-type="bibr" rid="B2">2</xref>). The incidence and prevalence of HFpEF continue to rise in tandem with the increasing age and burdens of obesity, sedentariness, and cardio metabolic disorders (<xref ref-type="bibr" rid="B3">3</xref>). HFpEF affects up to 32 million people worldwide (<xref ref-type="bibr" rid="B4">4</xref>). Functional capacity and quality of life are severely impaired in HFpEF, and morbidity and mortality are high (<xref ref-type="bibr" rid="B5">5</xref>). Patients with HFpEF are hospitalized approximately 1.4 times per year and have an annual mortality rate of approximately 15&#x0025; (<xref ref-type="bibr" rid="B4">4</xref>). Effective treatments for HFpEF are still lacking (<xref ref-type="bibr" rid="B6">6</xref>, <xref ref-type="bibr" rid="B7">7</xref>), despite the inhibitors of sodium-glucose transport protein 2 (SGLT2) inhibitors, which have demonstrated positive effects on the prognosis of HFpEF patients (<xref ref-type="bibr" rid="B8">8</xref>, <xref ref-type="bibr" rid="B9">9</xref>). Therefore, it is of great significance for disease management to investigate the prognostic factors of patients with HFpEF.</p>
<p>Uric acid, the end-product of purine metabolism in humans, is not only a cause of gout, but also may play a role in developing cardiovascular diseases (CVD) (<xref ref-type="bibr" rid="B10">10</xref>, <xref ref-type="bibr" rid="B11">11</xref>). A systematic review and meta-analysis published in 2021 indicated that serum uric acid is positively associated with the risk of adverse events in chronic HF patients (<xref ref-type="bibr" rid="B12">12</xref>). Another systematic review and meta-analysis demonstrated that every 1&#x2005;mg/dl reduction in uric acid was associated with a significantly lower risk of a composite of cardiovascular (CV) death and hospitalization for HF (<xref ref-type="bibr" rid="B13">13</xref>). Previous systematic reviews or meta-analyses have focused on the relationship between uric acid levels and the prognosis of HF patients. There has not yet been a meta-analysis examining the association between uric acid levels and the outcomes for patients with HFpEF. In addition, several studies have found a relationship between uric acid-lowering therapy and prognosis in HF. A systematic review and meta-analysis of clinical studies found that uric acid-lowering treatments increased all-cause and CV mortality (<xref ref-type="bibr" rid="B14">14</xref>). In a recent meta-analysis, targeting uric acid-lowering did not improve the prognosis of patients with HF (<xref ref-type="bibr" rid="B15">15</xref>). In view of the conflicting results and the lack of meta-analysis on the outcome of uric acid-lowering therapy in patients with HFpEF, a meta-analysis is warranted.</p>
<p>Herein, this meta-analysis aims to investigate the relationship between serum uric acid levels and the therapeutic impact of uric acid-lowering therapy on the clinical outcomes of patients with HFpEF. This meta-analysis may contribute to the management of patients with HFpEF.</p>
</sec>
<sec id="s2" sec-type="methods"><title>Methods</title>
<p>This study followed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines (<xref ref-type="bibr" rid="B16">16</xref>).</p>
<sec id="s2a"><title>Search methods for identification of studies</title>
<p>From inception to October 21, 2023, PubMed, Embase, Cochrane Library, and Web of Science databases were searched. English search terms include &#x201C;serum uric acid&#x201D; AND &#x201C;urate lowering drug&#x201D; AND &#x201C;heart failure&#x201D;. The search strategy of the PubMed database was shown in <xref ref-type="sec" rid="s10">Supplementary Material Table S1</xref>. The retrieved literature was imported into EndNote20, where an initial screening was conducted by reviewing the titles and abstracts. Following this preliminary assessment, full texts of the screened literature were read to exclude studies that did not meet the inclusion criteria. Subsequently, the remaining literature was incorporated into this study. Search strategies were methodically executed by two independent researchers (Linzhi Li and Ying Chang), with any arising discrepancies resolved through consultation with a third author (Fei Li).</p>
</sec>
<sec id="s2b"><title>Eligibility criteria</title>
<p>Inclusion criteria were formulated based on the Population, Intervention, Comparator, Outcome, and Study design (PICOS) framework, encompassing: (1) P: patients with HFpEF; (2) I and C: serum uric acid levels/uric acid-lowering therapy; (3) O: all-cause mortality, CV mortality, HF hospitalization, and Kansas City Cardiomyopathy Questionnaire (KCCQ) clinical summary score; (3) S: cohort studies, and RCTs; (5) literature published in English.</p>
<p>Exclusion criteria: (1) animal experimental studies; (2) withdrawn studies; (3) reviews, meta-analyses, guidelines, consensus statements, errata, case reports, conference abstracts, editorial materials, letters, and trial registration records; (4) studies not relevant to the topic.</p>
</sec>
<sec id="s2c"><title>Data extraction</title>
<p>Two reviewers (Linzhi Li and Ying Chang) independently collected data from the selected studies. Data extracted from the included studies encompassed the first name of the author, year of publication, country, study design, sample size, age (years), sample size of male, LVEF (&#x0025;), definition of higher uric acid level (mg/dl), follow-up, and outcome. In instances of discrepancy, consensus was reached by referring to a third investigator (Fei Li) for arbitration.</p>
</sec>
<sec id="s2d"><title>Assessment of quality of studies</title>
<p>The Newcastle-Ottawa Scale (NOS) (<xref ref-type="bibr" rid="B17">17</xref>) was used to assess the quality of cohort studies, with a total score of 9 points. Studies scoring 0&#x2013;3 points were considered low quality, 4&#x2013;6 points as medium quality, and 7&#x2013;9 points as high quality. The Jadad scale (<xref ref-type="bibr" rid="B18">18</xref>) was utilized to evaluate the quality of RCTs, which comprises four items: generation of random sequences, allocation concealment, blinding (each item scoring up to 2 points), and withdrawals and dropouts (scoring 1 point). Studies scoring 1&#x2013;3 points were deemed low quality, while those scoring 4&#x2013;7 points were classified as high quality.</p>
</sec>
<sec id="s2e"><title>Statistical analysis</title>
<p>All data were analyzed using Stata 15.0 software. For categorical variables, the relative risk (RR) or hazard ratio (HR) was used as the effect size, while for continuous outcomes, the weighted mean difference (WMD) was employed. The results of the combined effect size were presented with the effect size and its 95&#x0025; confidence interval (CI). Heterogeneity tests were conducted for each outcome measure, with a random-effects model analysis being performed if <italic>I</italic><sup>2</sup>&#x2009;&#x2265;&#x2009;50&#x0025;, and a fixed-effects model analysis otherwise. Subgroup analyses were carried out based on sample size (&#x003C;1,000, and &#x2265;1,000), follow-up duration (&#x003C;2 years, and &#x2265;2 years), literature quality (&#x003C;7, and &#x2265;7), ethnicity (Non-Asian, and Asian), study type (prospective, and retrospective), type of HF (acute, and chronic), hyperuricemia (yes, or no), LVEF (&#x2265;45&#x0025;, or &#x2265;50&#x0025;), and the type of uric acid-lowering therapy used (traditional, or novel). Sensitivity analyses were conducted for all outcomes. When ten or more studies were included for outcomes, publication bias was assessed with funnel plot. A <italic>P</italic> value of &#x003C;0.05 was considered statistically significant.</p>
</sec>
</sec>
<sec id="s3" sec-type="results"><title>Results</title>
<sec id="s3a"><title>Study selection process and characteristics of included studies</title>
<p>Initially, records were identified through various English databases: PubMed (<italic>n</italic>&#x2009;&#x003D;&#x2009;6,108), Web of Science (<italic>n</italic>&#x2009;&#x003D;&#x2009;9,266), Embase (<italic>n</italic>&#x2009;&#x003D;&#x2009;10,409), and the Cochrane Library (<italic>n</italic>&#x2009;&#x003D;&#x2009;364), totaling 26,147 records. A total of 10,824 duplicates were removed, leaving 15,323 records. These remaining records were then screened by title and abstract, resulting in the exclusion of 15,227 records. After exclusion, 96 full-text articles were assessed for eligibility. Finally, 12 (<xref ref-type="bibr" rid="B19">19</xref>&#x2013;<xref ref-type="bibr" rid="B30">30</xref>) studies were included in the analysis. <xref ref-type="fig" rid="F1">Figure&#x00A0;1</xref> represents the literature screening process. The span of literature included in the study ranges from 2012 to 2023. Among the included articles, there were three RCTs and nine cohort studies. Six of the included articles were classified as high-quality studies. The shortest follow-up duration in the included literature was 12 weeks, while the longest was 4.81 years. <xref ref-type="table" rid="T1">Tables&#x00A0;1</xref>, <xref ref-type="table" rid="T2">2</xref> summarize the characteristics of the included studies.</p>
<fig id="F1" position="float"><label>Figure 1</label>
<caption><p>The flowchart of the literature screening process.</p></caption>
<graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="fcvm-11-1403242-g001.tif"/>
</fig>
<table-wrap id="T1" position="float"><label>Table 1</label>
<caption><p>Basic information of literature on the association between uric acid and adverse outcomes of HF.</p></caption>
<table frame="hsides" rules="groups">
<colgroup>
<col align="left"/>
<col align="center"/>
<col align="left"/>
<col align="left"/>
<col align="center"/>
<col align="center"/>
<col align="center"/>
<col align="center"/>
<col align="left"/>
<col align="center"/>
<col align="left"/>
<col align="left"/>
<col align="left"/>
<col align="left"/>
<col align="center"/>
</colgroup>
<thead>
<tr>
<th valign="top" align="left">Author</th>
<th valign="top" align="center">Year</th>
<th valign="top" align="center">Country</th>
<th valign="top" align="center">Study<break/>design</th>
<th valign="top" align="center">Sample size</th>
<th valign="top" align="center">Age</th>
<th valign="top" align="center">Male&#xFF0C;<italic>n</italic></th>
<th valign="top" align="center">LVEF (&#x0025;)</th>
<th valign="top" align="center">Definition of higher<break/>UA level (mg/dl)</th>
<th valign="top" align="center">Follow-up</th>
<th valign="top" align="center">Adjustment variables</th>
<th valign="top" align="center">Univariate, HR (95&#x0025; CI)</th>
<th valign="top" align="center">Multivariable, HR (95&#x0025; CI)</th>
<th valign="top" align="center">Outcome</th>
<th valign="top" align="center">NOS, Quality score</th>
</tr>
</thead>
<tbody>
<tr>
<td valign="top" align="left">Shimizu</td>
<td valign="top" align="center">2015</td>
<td valign="top" align="center">Japan</td>
<td>Prospective<break/>cohort</td>
<td valign="top" align="center">424</td>
<td valign="top" align="center">68.36&#x2009;&#x00B1;&#x2009;14.86</td>
<td valign="top" align="center">212</td>
<td valign="top" align="center">61.02&#x2009;&#x00B1;&#x2009;9.10</td>
<td valign="top" align="center">7</td>
<td valign="top" align="center">897 days</td>
<td>Age, gender, systolic blood pressure, LVEF,B-type natriuretic peptide, presence of ischemic etiology, diabetes, atrial fibrillation, chronic kidney disease, anemia, hyperuricemia, and usage of blockers, renin-angiotensin-aldosterone system inhibitors, and diuretics</td>
<td valign="top" align="left">Cardiovascular mortality, 3.53 (1.35, 9.23); All-cause mortality, 2.08 (1.25, 3.46)</td>
<td valign="top" align="left">Cardiovascular mortality, 1.85 (0.58, 5.87); All-cause mortality, 1.98 (1.04, 3.79)</td>
<td valign="top" align="left">All-cause mortality<break/>Cardiovascular mortality</td>
<td>5</td>
</tr>
<tr>
<td valign="top" align="left">Selvaraj</td>
<td>2020</td>
<td>Multiple country</td>
<td>Prospective<break/>cohort</td>
<td>4,795</td>
<td>72.71&#x2009;&#x00B1;&#x2009;8.45</td>
<td>2,316</td>
<td>58&#x2009;&#x00B1;&#x2009;8</td>
<td>66&#x2013;90 years, men 8<break/>women 7.3<break/>18&#x2013;65 years, women 6.9</td>
<td>4 months</td>
<td>Age, sex, race, region, systolic blood pressure, heart rate, ejection fraction, NYHA class, history of HF hospitalization, duration of HF, atrial fibrillation, diabetes, body mass index, prior myocardial infarction, prior stroke, estimated glomerular filtration rate, haemoglobin, sodium, albumin, randomized treatment, diuretic use and NT-proBNP</td>
<td valign="top" align="left">Cardiovascular mortality, 1.71 (1.40, 2.09); All-cause mortality, 1.56 (1.33, 1.82); HF hospitalization, 2.05 (1.72, 2.45)</td>
<td valign="top" align="left">Cardiovascular mortality,1.58 (1.26, 1.98); All-cause mortality, 1.42 (1.18, 1.69); HF hospitalization, 1.61 (1.34, 1.94)</td>
<td valign="top" align="left">All-cause mortality<break/>Cardiovascular mortality<break/>HF hospitalization</td>
<td>7</td>
</tr>
<tr>
<td valign="top" align="left">Nishino</td>
<td>2022</td>
<td>Japan</td>
<td>Prospective<break/>cohort</td>
<td>464</td>
<td>81.81&#x2009;&#x00B1;&#x2009;8.23</td>
<td>231</td>
<td>60.34&#x2009;&#x00B1;&#x2009;7.85</td>
<td>7</td>
<td>480 days</td>
<td>NR</td>
<td valign="top" align="left">NR</td>
<td valign="top" align="left">NR</td>
<td valign="top" align="left">All-cause mortality<break/>HF hospitalization</td>
<td>6</td>
</tr>
<tr>
<td valign="top" align="left">Ambrosio</td>
<td>2021</td>
<td>Italy</td>
<td>Prospective<break/>cohort</td>
<td>4,938</td>
<td>64.6 (13.20)&#x002A;</td>
<td>3,562</td>
<td>37.5 (13.48)</td>
<td>6.61</td>
<td>18 months</td>
<td>NR</td>
<td valign="top" align="left">NR</td>
<td valign="top" align="left">NR</td>
<td valign="top" align="left">Cardiovascular mortality<break/>HF hospitalization</td>
<td>7</td>
</tr>
<tr>
<td valign="top" align="left">Carnicelli</td>
<td>2020</td>
<td>USA</td>
<td>Retrospective<break/>cohort</td>
<td>7,004</td>
<td>68.16&#x2009;&#x00B1;&#x2009;15.86</td>
<td>2,988</td>
<td>NR</td>
<td>6</td>
<td>2.6 years</td>
<td>Demographics (age, gender, and race),co-morbidities (diabetes, hypertension, and prior myocardial infarction), year of index echocardiogram (categorized), baseline measures (left ventricular ejection fraction, heart rate, systolic blood pressure, and body mass index), baseline medications (beta-blocker, angiotensin converting enzyme inhibitor, angiotensin receptor blocker, calcium channel blockers, and loop diuretic), and baseline laboratory measures (sodium, hemoglobin, blood urea nitrogen, and creatinine)</td>
<td valign="top" align="left">All-cause mortality, 1.24 (1.13, 1.36); HF hospitalization, 1.27 (1.17, 1.38)</td>
<td valign="top" align="left">All-cause mortality, 0.98 (0.89, 1.08); HF hospitalization, 1.03 (0.94, 1.12)</td>
<td valign="top" align="left">All-cause mortality<break/>HF hospitalization</td>
<td>6</td>
</tr>
<tr>
<td valign="top" align="left">Deng</td>
<td>2023</td>
<td>China</td>
<td>Prospective<break/>cohort</td>
<td>210</td>
<td>74 (67, 81)&#x002A;</td>
<td>86</td>
<td>61 (58, 65)</td>
<td>7</td>
<td>278 days</td>
<td>Gender, NYHA class, coronary artery disease, atrial fibrillation, right ventricular dysfunction, NT-proBNP, and Cr</td>
<td valign="top" align="left">HF hospitalization, 2.98 (1.70, 5.21)</td>
<td valign="top" align="left">HF hospitalization, 3.03 (1.52&#x2013;6.03)</td>
<td valign="top" align="left">HF hospitalization</td>
<td>7</td>
</tr>
<tr>
<td valign="top" align="left">Kobayashi</td>
<td>2020</td>
<td>Japan</td>
<td>Prospective<break/>cohort</td>
<td>516</td>
<td>78&#x2009;&#x00B1;&#x2009;11</td>
<td>256</td>
<td>60&#x2009;&#x00B1;&#x2009;8</td>
<td>7.4</td>
<td>749 days</td>
<td>Age, male, systolic blood pressure, sodium, log brain natriuretic peptide, albumin, blood urea nitrogen, use of diuretics before admission</td>
<td valign="top" align="left">NR</td>
<td valign="top" align="left">All-cause mortality, 1.23 (1.10, 1.39)</td>
<td valign="top" align="left">All-cause mortality</td>
<td>6</td>
</tr>
<tr>
<td valign="top" align="left">Wang</td>
<td>2023</td>
<td>China</td>
<td>Retrospective<break/>cohort</td>
<td>7,769</td>
<td>62.64&#x2009;&#x00B1;&#x2009;15.12</td>
<td>6,244</td>
<td>NR</td>
<td>7</td>
<td>4.81 years</td>
<td>NR</td>
<td valign="top" align="left">NR</td>
<td valign="top" align="left">NR</td>
<td valign="top" align="left">All-cause mortality</td>
<td>5</td>
</tr>
</tbody>
</table>
<table-wrap-foot>
<fn id="table-fn1"><p>HF, heart failure; USA, United States of America; NR, non-reported; LVEF, left ventricular ejection fraction; UA, uric acid; NYHA, New York Heart Association; NT-proBNP, N-terminal pro-B-type natriuretic peptide; Cr, creatinine; HR, hazard ratio; CI, confidence interval; NOS, Newcastle-Ottawa Scale.</p></fn>
<fn id="table-fn71"><p>&#x002A;Stands for median (IQR).</p></fn>
</table-wrap-foot>
</table-wrap>
<table-wrap id="T2" position="float"><label>Table 2</label>
<caption><p>Basic information of literature on the association between uric acid-lowering therapy and adverse outcomes of HF.</p></caption>
<table frame="hsides" rules="groups">
<colgroup>
<col align="left"/>
<col align="left"/>
<col align="left"/>
<col align="left"/>
<col align="center"/>
<col align="center"/>
<col align="center"/>
<col align="center"/>
<col align="center"/>
<col align="center"/>
<col align="left"/>
<col align="left"/>
<col align="center"/>
<col align="center"/>
</colgroup>
<thead>
<tr>
<th valign="top" align="left">Author</th>
<th valign="top" align="center">Year</th>
<th valign="top" align="center">Country</th>
<th valign="top" align="center">Study<break/>design</th>
<th valign="top" align="center">Sample size</th>
<th valign="top" align="center">Age</th>
<th valign="top" align="center">Male, <italic>n</italic></th>
<th valign="top" align="center">Follow-up</th>
<th valign="top" align="center">Adjustment variables</th>
<th valign="top" align="center">Univariate, HR (95&#x0025; CI)</th>
<th valign="top" align="center">Multivariable, HR (95&#x0025; CI)</th>
<th valign="top" align="center">Outcome</th>
<th>NOS, quality<break/>score</th>
<th>Jadad, quality<break/>score</th>
</tr>
</thead>
<tbody>
<tr>
<td valign="top" align="left">M&#x00E1;lek</td>
<td>2012</td>
<td>Czech Republic</td>
<td>Prospective<break/>cohort</td>
<td>1,255</td>
<td>73.4 (45.7, 87.7)<sup>a</sup></td>
<td>714</td>
<td>2 years</td>
<td>NR</td>
<td>NR</td>
<td>NR</td>
<td>All-cause mortality</td>
<td>6</td>
<td/>
</tr>
<tr>
<td valign="top" align="left">Solomon</td>
<td>2019</td>
<td>Multiple country</td>
<td>RCT</td>
<td>4,796</td>
<td>72.75&#x2009;&#x00B1;&#x2009;8.40</td>
<td>2,317</td>
<td>35 months</td>
<td>NR</td>
<td>NR</td>
<td>NR</td>
<td>All-cause mortality<break/>Cardiovascular death<break/>HF hospitalization<break/>KCCQ-CS</td>
<td/>
<td>4</td>
</tr>
<tr>
<td valign="top" align="left">Nassif</td>
<td>2021</td>
<td>Multiple country</td>
<td>RCT</td>
<td>324</td>
<td>70.35&#x2009;&#x00B1;&#x2009;10.48</td>
<td>140</td>
<td>12 weeks</td>
<td>NR</td>
<td>NR</td>
<td>Cardiovascular mortality, 0.89 (0.70, 1.13); All-cause mortality, 1.02 (0.86, 1.21); HF hospitalization, 0.78 (0.64, 0.95)</td>
<td>KCCQ-CS</td>
<td/>
<td>7</td>
</tr>
<tr>
<td valign="top" align="left">Nishino</td>
<td>2022</td>
<td>Japan</td>
<td>Prospective<break/>cohort</td>
<td>291</td>
<td>81.5&#x2009;&#x00B1;&#x2009;7.33</td>
<td>146</td>
<td>480 days</td>
<td>NR</td>
<td>NR</td>
<td>NR</td>
<td>All-cause mortality<break/>HF hospitalization</td>
<td>6</td>
<td/>
</tr>
<tr>
<td valign="top" align="left">Anker</td>
<td>2022</td>
<td>Multiple country</td>
<td>RCT</td>
<td>4,005</td>
<td>72.8&#x2009;&#x00B1;&#x2009;9.2</td>
<td>1,986</td>
<td>24 months</td>
<td>NR</td>
<td>NR</td>
<td>All-cause mortality, 1.63 (1.08, 2.45)</td>
<td>All-cause mortality<break/>Cardiovascular death<break/>HF rehospitalization</td>
<td/>
<td>4</td>
</tr>
</tbody>
</table>
<table-wrap-foot>
<fn id="table-fn2"><p>HF, heart failure; KCCQ-CS, Kansas City cardiomyopathy questionnaire clinical summary score; NT-proBNP, N-terminal pro B-type natriuretic peptide; NYHA, New York Heart Association; <sup>a</sup>median (interquartile range); NR, non-reported; HR, hazard ratio; CI, confidence interval; NOS, Newcastle-Ottawa Scale.</p></fn>
</table-wrap-foot>
</table-wrap>
</sec>
<sec id="s3b"><title>Meta-analysis of the association between serum uric acid level and all-cause mortality in patients with HFpEF</title>
<sec id="s3b1"><title>High serum uric acid level vs. low serum uric acid level (RR)</title>
<p>A total of six studies were included to assess the association between serum uric acid levels and all-cause mortality in patients with HFpEF. Due to high heterogeneity, as indicated by an <italic>I</italic><sup>2</sup> of 87.2&#x0025;, a random-effects model was utilized for the analysis. The pooled analysis suggested that elevated serum uric acid levels were associated with an increased risk of all-cause mortality in patients with HFpEF (RR: 1.21, 95&#x0025; CI: 1.06&#x2013;1.37, <italic>P&#x2009;</italic>&#x003D;&#x2009;0.004) (<xref ref-type="fig" rid="F2">Figure&#x00A0;2A</xref>, <xref ref-type="table" rid="T3">Table&#x00A0;3</xref>). The subgroup analyses showed that in studies with a sample size of 1,000 or greater (RR: 1.28, 95&#x0025; CI: 1.12&#x2013;1.46, <italic>P</italic>&#x2009;&#x003C;&#x2009;0.001), in studies with a follow-up duration of 2 years or longer (RR: 1.17, 95&#x0025; CI: 1.01&#x2013;1.35, <italic>P</italic>&#x2009;&#x003D;&#x2009;0.037), regardless of whether the quality score was less than 7 or 7 and above, among non-Asian populations (RR: 1.16, 95&#x0025; CI: 1.08&#x2013;1.24, <italic>P</italic>&#x2009;&#x003C;&#x2009;0.001), in retrospective study designs (RR: 1.19, 95&#x0025; CI: 1.11&#x2013;1.28, <italic>P</italic>&#x2009;&#x003C;&#x2009;0.001), and among patients with chronic HF (RR: 1.25, 95&#x0025; CI: 1.14&#x2013;1.37, <italic>P</italic>&#x2009;&#x003C;&#x2009;0.001), elevated serum uric acid levels were significantly associated with increased all-cause mortality in patients with HFpEF (<xref ref-type="table" rid="T3">Table&#x00A0;3</xref>).</p>
<fig id="F2" position="float"><label>Figure 2</label>
<caption><p>Meta-analysis of the association between serum uric acid level and all-cause mortality in patients with HFpEF; (<bold>A</bold>), high serum uric acid level; (<bold>B</bold>), per 1&#x2005;mg/dl rise of serum uric acid level.</p></caption>
<graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="fcvm-11-1403242-g002.tif"/>
</fig>
<table-wrap id="T3" position="float"><label>Table 3</label>
<caption><p>Meta-analysis of the association between serum uric acid level and outcomes in patients with HFpEF.</p></caption>
<table frame="hsides" rules="groups">
<colgroup>
<col align="left"/>
<col align="left"/>
<col align="center"/>
<col align="center"/>
<col align="center"/>
</colgroup>
<thead>
<tr>
<th valign="top" align="left">Outcomes</th>
<th valign="top" align="center">Indicators</th>
<th valign="top" align="center">RR/HR</th>
<th valign="top" align="center"><italic>P</italic></th>
<th valign="top" align="center"><italic>I</italic><sup>2</sup></th>
</tr>
</thead>
<tbody>
<tr>
<td valign="top" align="left">Cardiovascular mortality (RR)</td>
<td valign="top" align="left">Overall</td>
<td valign="top" align="center">1.71 (1.42, 2.04)</td>
<td valign="top" align="center">&#x003C;0.001</td>
<td valign="top" align="center">15.9&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left" rowspan="19">All-cause mortality (RR)</td>
<td valign="top" align="left">Overall</td>
<td valign="top" align="center">1.21 (1.06, 1.37)</td>
<td valign="top" align="center">0.004</td>
<td valign="top" align="center">87.2&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Sample size</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
</tr>
<tr>
<td valign="top" align="left">&#x003C;1,000</td>
<td valign="top" align="center">1.12 (0.913, 1.37)</td>
<td valign="top" align="center">0.279</td>
<td valign="top" align="center">79.3&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">&#x2265;1,000</td>
<td valign="top" align="center">1.28 (1.12, 1.46)</td>
<td valign="top" align="center">&#x003C;0.001</td>
<td valign="top" align="center">82.3&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Follow-up</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
</tr>
<tr>
<td valign="top" align="left">&#x003C;2 years</td>
<td valign="top" align="center">1.28 (0.92, 1.77)</td>
<td valign="top" align="center">0.144</td>
<td valign="top" align="center">87.0&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">&#x2265;2 years</td>
<td valign="top" align="center">1.17 (1.01, 1.35)</td>
<td valign="top" align="center">0.037</td>
<td valign="top" align="center">91.3&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Quality score</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
</tr>
<tr>
<td valign="top" align="left">&#x003C;7</td>
<td valign="top" align="center">1.14 (1.02, 1.29)</td>
<td valign="top" align="center">0.025</td>
<td valign="top" align="center">82.9&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">&#x2265;7</td>
<td valign="top" align="center">1.51 (1.31, 1.74)</td>
<td valign="top" align="center">&#x003C;0.001</td>
<td valign="top" align="center">0.0&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Ethnicity</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
</tr>
<tr>
<td valign="top" align="left">Non-Asian</td>
<td valign="top" align="center">1.16 (1.08, 1.24)</td>
<td valign="top" align="center">&#x003C;0.001</td>
<td valign="top" align="center">0.0&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Asian</td>
<td valign="top" align="center">1.16 (0.98, 1.38)</td>
<td valign="top" align="center">0.095</td>
<td valign="top" align="center">86.3&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Study design</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
</tr>
<tr>
<td valign="top" align="left">Prospective</td>
<td valign="top" align="center">1.26 (0.98, 1.60)</td>
<td valign="top" align="center">0.070</td>
<td valign="top" align="center">91.1&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Retrospective</td>
<td valign="top" align="center">1.19 (1.11, 1.28)</td>
<td valign="top" align="center">&#x003C;0.001</td>
<td valign="top" align="center">41.9&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">HF type</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
</tr>
<tr>
<td valign="top" align="left">Acute</td>
<td valign="top" align="center">1.12 (0.91, 1.37)</td>
<td valign="top" align="center">0.279</td>
<td valign="top" align="center">79.3&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Chronic</td>
<td valign="top" align="center">1.25 (1.14, 1.37)</td>
<td valign="top" align="center">&#x003C;0.001</td>
<td valign="top" align="center">0.0&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">All-cause mortality (HR)</td>
<td valign="top" align="left">Overall</td>
<td valign="top" align="center">1.20 (1.14, 1.25)</td>
<td valign="top" align="center">&#x003C;0.001</td>
<td valign="top" align="center">0.0&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left" rowspan="16">HF hospitalization (RR)</td>
<td valign="top" align="left">Overall</td>
<td valign="top" align="center">1.42 (0.97, 2.09)</td>
<td valign="top" align="center">0.070</td>
<td valign="top" align="center">97.9&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Sample size</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
</tr>
<tr>
<td valign="top" align="left">&#x003C;1,000</td>
<td valign="top" align="center">1.03 (0.86, 1.23)</td>
<td valign="top" align="center">0.749</td>
<td valign="top" align="center">0.0&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">&#x2265;1,000</td>
<td valign="top" align="center">1.60 (0.99, 2.57)</td>
<td valign="top" align="center">0.053</td>
<td valign="top" align="center">98.5&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Follow-up</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
</tr>
<tr>
<td valign="top" align="left">&#x003C;2 years</td>
<td valign="top" align="center">1.56 (0.95, 2.58)</td>
<td valign="top" align="center">0.082</td>
<td valign="top" align="center">95.4&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">&#x2265;2 years</td>
<td valign="top" align="center">1.12 (1.06, 1.18)</td>
<td valign="top" align="center">&#x003C;0.001</td>
<td valign="top" align="center">0.0&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Quality score</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
</tr>
<tr>
<td valign="top" align="left">&#x003C;7</td>
<td valign="top" align="center">1.11 (1.05, 1.17)</td>
<td valign="top" align="center">&#x003C;0.001</td>
<td valign="top" align="center">0.0&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">&#x2265;7</td>
<td valign="top" align="center">1.99 (1.84, 2.16)</td>
<td valign="top" align="center">&#x003C;0.001</td>
<td valign="top" align="center">0.0&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Ethnicity</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
</tr>
<tr>
<td valign="top" align="left">Non-Asian</td>
<td valign="top" align="center">1.39 (0.84, 2.32)</td>
<td valign="top" align="center">0.203</td>
<td valign="top" align="center">81.9</td>
</tr>
<tr>
<td valign="top" align="left">Asian</td>
<td valign="top" align="center">1.03 (0.86, 1.23)</td>
<td valign="top" align="center">0.749</td>
<td valign="top" align="center">0.0&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Study design</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
</tr>
<tr>
<td valign="top" align="left">Prospective</td>
<td valign="top" align="center">1.56 (0.95, 2.58)</td>
<td valign="top" align="center">0.082</td>
<td valign="top" align="center">95.4&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Retrospective</td>
<td valign="top" align="center">1.12 (1.06, 1.18)</td>
<td valign="top" align="center">&#x003C;0.001</td>
<td valign="top" align="center">0.0&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left" rowspan="16">HF hospitalization (HR)</td>
<td valign="top" align="left">Overall</td>
<td valign="top" align="center">1.61 (1.12, 2.34)</td>
<td valign="top" align="center">0.011</td>
<td valign="top" align="center">90.8&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Sample size</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
</tr>
<tr>
<td valign="top" align="left">&#x003C;1,000</td>
<td valign="top" align="center">1.70 (0.58, 4.95)</td>
<td valign="top" align="center">0.332</td>
<td valign="top" align="center">89.4&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">&#x2265;1,000</td>
<td valign="top" align="center">1.60 (1.00, 2.56)</td>
<td valign="top" align="center">0.049</td>
<td valign="top" align="center">95.7&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Follow-up</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
</tr>
<tr>
<td valign="top" align="left">&#x003C;2 years</td>
<td valign="top" align="center">1.80 (1.06, 3.07)</td>
<td valign="top" align="center">0.031</td>
<td valign="top" align="center">83.9&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">&#x2265;2 years</td>
<td valign="top" align="center">1.27 (1.17, 1.38)</td>
<td valign="top" align="center">&#x003C;0.001</td>
<td valign="top" align="center">0.0&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Quality score</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
</tr>
<tr>
<td valign="top" align="left">&#x003C;7</td>
<td valign="top" align="center">1.23 (1.06, 1.44)</td>
<td valign="top" align="center">0.008</td>
<td valign="top" align="center">18.9&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">&#x2265;7</td>
<td valign="top" align="center">2.24 (1.64, 3.06)</td>
<td valign="top" align="center">&#x003C;0.001</td>
<td valign="top" align="center">36.1&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Ethnicity</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
</tr>
<tr>
<td valign="top" align="left">Non-Asian</td>
<td valign="top" align="center">1.27 (1.17, 1.38)</td>
<td valign="top" align="center">&#x003C;0.001</td>
<td valign="top" align="center">0.0&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Asian</td>
<td valign="top" align="center">1.70 (0.58, 4.95)</td>
<td valign="top" align="center">0.332</td>
<td valign="top" align="center">89.4&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Study design</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
</tr>
<tr>
<td valign="top" align="left">Prospective</td>
<td valign="top" align="center">1.80 (1.06, 3.07)</td>
<td valign="top" align="center">0.031</td>
<td valign="top" align="center">83.9&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Retrospective</td>
<td valign="top" align="center">1.27 (1.17, 1.38)</td>
<td valign="top" align="center">&#x003C;0.001</td>
<td valign="top" align="center">0.0&#x0025;</td>
</tr>
</tbody>
</table>
<table-wrap-foot>
<fn id="table-fn3"><p>HFpEF, heart failure with preserved ejection fraction; HF, heart failure; RR, relative risk; HR, hazard ratio.</p></fn>
</table-wrap-foot>
</table-wrap>
</sec>
<sec id="s3b2"><title>Per 1&#x2005;mg/dl rise of serum uric acid level (HR)</title>
<p>Two studies were included for analysis between every 1&#x2005;mg/dl rise in serum uric acid level and all-cause mortality in patients with HFpEF. Heterogeneity testing yielded an <italic>I</italic><sup>2</sup> of 0.0&#x0025;, thus a fixed-effect model was employed for the analysis. The pooled analysis demonstrated that for each 1&#x2005;mg/dl elevation in serum uric acid levels, the risk of all-cause mortality increased (HR: 1.20, 95&#x0025; CI: 1.14&#x2013;1.25, <italic>P</italic>&#x2009;&#x003C;&#x2009;0.001) (<xref ref-type="fig" rid="F2">Figure&#x00A0;2B</xref>, <xref ref-type="table" rid="T3">Table&#x00A0;3</xref>).</p>
</sec>
</sec>
<sec id="s3c"><title>Meta-analysis of the association between serum uric acid level and CV mortality in patients with HFpEF</title>
<sec id="s3c1"><title>High serum uric acid level vs. low serum uric acid level</title>
<p>Three studies were included to assess the association between serum uric acid level and CV mortality in patients with HFpEF. The fixed-effect model analysis suggested a significant association between increased serum uric acid levels and a higher risk of CV mortality (RR: 1.71, 95&#x0025; CI: 1.42&#x2013;2.04, <italic>P</italic>&#x2009;&#x003C;&#x2009;0.001) (<xref ref-type="fig" rid="F3">Figure&#x00A0;3</xref>, <xref ref-type="table" rid="T3">Table&#x00A0;3</xref>).</p>
<fig id="F3" position="float"><label>Figure 3</label>
<caption><p>Meta-analysis of the association between serum uric acid level and CV mortality in patients with HFpEF.</p></caption>
<graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="fcvm-11-1403242-g003.tif"/>
</fig>
</sec>
</sec>
<sec id="s3d"><title>Meta-analysis of the association between serum uric acid level and HF hospitalization in patients with HFpEF</title>
<sec id="s3d1"><title>High serum uric acid level vs. low serum uric acid level (RR)</title>
<p>Four studies assessed the association between serum uric acid level and HF hospitalization in patients with HFpEF, with heterogeneity testing showing an <italic>I</italic><sup>2</sup> of 97.9&#x0025;. Consequently, analysis was conducted using a random-effects model. The outcome implied that elevated levels of serum uric acid did not have a significant correlation with HF hospitalization in patients with HFpEF (RR: 1.42, 95&#x0025; CI: 0.97&#x2013;2.09, <italic>P</italic>&#x2009;&#x003D;&#x2009;0.070) (<xref ref-type="fig" rid="F4">Figure&#x00A0;4A</xref>, <xref ref-type="table" rid="T3">Table&#x00A0;3</xref>). However, subgroup analyses demonstrated that in contexts where the follow-up period extends to 2 years or longer, the studies were of a retrospective nature, and there was a notable association between increased uric acid levels and hospitalization for HF.</p>
<fig id="F4" position="float"><label>Figure 4</label>
<caption><p>Meta-analysis of the association between serum uric acid level and HF hospitalization in patients with HFpEF; (<bold>A</bold>), RR; (<bold>B</bold>), HR.</p></caption>
<graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="fcvm-11-1403242-g004.tif"/>
</fig>
</sec>
<sec id="s3d2"><title>High serum uric acid level vs. low serum uric acid level (HR)</title>
<p>Four studies were included to examine the association between serum uric acid level (HR) and HF hospitalization in patients with HFpEF. The heterogeneity testing indicated an <italic>I</italic><sup>2</sup> of 90.8&#x0025;, leading to the use of a random-effects model for analysis. The results suggested that an increase in uric acid levels was associated with an increased risk of hospitalization due to HF (HR: 1.61, 95&#x0025; CI: 1.12&#x2013;2.34, <italic>P</italic>&#x2009;&#x003D;&#x2009;0.011) (<xref ref-type="fig" rid="F4">Figure&#x00A0;4B</xref>, <xref ref-type="table" rid="T3">Table&#x00A0;3</xref>). Subgroup analysis revealed that this relationship holds true across studies with a sample size of 1,000 or more, regardless of the duration of follow-up, the quality of the studies, whether the HF was acute or chronic, and also among non-Asian populations (<xref ref-type="table" rid="T3">Table&#x00A0;3</xref>).</p>
</sec>
</sec>
<sec id="s3e"><title>Meta-analysis of the association between uric acid-lowering therapy and all-cause mortality in patients with HFpEF</title>
<sec id="s3e1"><title>Experimental vs. control (RR)</title>
<p>The analysis incorporated three studies to assess the association between uric acid-lowering therapy and all-cause mortality in patients with HFpEF, revealing no heterogeneity (<italic>I</italic><sup>2</sup>&#x2009;&#x003D;&#x2009;0.0&#x0025;), and hence, a fixed-effect model was utilized. The results showed that lowering uric acid levels through treatment did not significantly alter the outcome for all-cause mortality in patients with HFpEF (RR: 0.97, 95&#x0025; CI: 0.89&#x2013;1.06, <italic>P</italic>&#x2009;&#x003D;&#x2009;0.532) (<xref ref-type="fig" rid="F5">Figure&#x00A0;5A</xref>, <xref ref-type="table" rid="T4">Table&#x00A0;4</xref>). This conclusion remained consistent across subgroups defined by the presence of hyperuricemia, LVEF, and the type of uric acid-lowering therapy used (<xref ref-type="table" rid="T4">Table&#x00A0;4</xref>).</p>
<fig id="F5" position="float"><label>Figure 5</label>
<caption><p>Meta-analysis of the association between uric acid-lowering therapy and all-cause mortality in patients with HFpEF; (<bold>A</bold>), RR; (<bold>B</bold>), HR.</p></caption>
<graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="fcvm-11-1403242-g005.tif"/>
</fig>
<table-wrap id="T4" position="float"><label>Table 4</label>
<caption><p>Meta-analysis of the association between uric acid-lowering therapy and outcome in patients with HFpEF.</p></caption>
<table frame="hsides" rules="groups">
<colgroup>
<col align="left"/>
<col align="left"/>
<col align="center"/>
<col align="center"/>
<col align="center"/>
</colgroup>
<thead>
<tr>
<th valign="top" align="left">Outcomes</th>
<th valign="top" align="center">Indicators</th>
<th valign="top" align="center">RR/HR/WMD</th>
<th valign="top" align="center"><italic>P</italic></th>
<th valign="top" align="center"><italic>I</italic><sup>2</sup></th>
</tr>
</thead>
<tbody>
<tr>
<td valign="top" align="left">Cardiovascular mortality</td>
<td valign="top" align="left">Overall</td>
<td valign="top" align="center">0.92 (0.80, 1.07)</td>
<td valign="top" align="center">0.274</td>
<td valign="top" align="center">0.0&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left" rowspan="10">All-cause mortality (RR)</td>
<td valign="top" align="left">Overall</td>
<td valign="top" align="center">0.97 (0.89, 1.06)</td>
<td valign="top" align="center">0.532</td>
<td valign="top" align="center">0.0&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Hyperuricemia</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
</tr>
<tr>
<td valign="top" align="left">No</td>
<td valign="top" align="center">0.98 (0.89, 1.09)</td>
<td valign="top" align="center">0.746</td>
<td valign="top" align="center">0.0&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Yes</td>
<td valign="top" align="center">0.916 (0.82, 1.02)</td>
<td valign="top" align="center">0.115</td>
<td valign="top" align="center">0.0&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">LVEF</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
</tr>
<tr>
<td valign="top" align="left">&#x2265;45&#x0025;</td>
<td valign="top" align="center">0.97 (0.85, 1.12)</td>
<td valign="top" align="center">0.693</td>
<td valign="top" align="center">87.0&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">&#x2265;50&#x0025;</td>
<td valign="top" align="center">0.97 (0.87, 1.09)</td>
<td valign="top" align="center">0.621</td>
<td valign="top" align="center">0.0&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Uric acid-lowering drugs</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
</tr>
<tr>
<td valign="top" align="left">Traditional</td>
<td valign="top" align="center">0.92 (0.82, 1.02)</td>
<td valign="top" align="center">0.115</td>
<td valign="top" align="center">0.0&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Novel</td>
<td valign="top" align="center">0.98 (0.89, 1.09)</td>
<td valign="top" align="center">0.746</td>
<td valign="top" align="center">0.0&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left" rowspan="10">All-cause mortality (HR)</td>
<td valign="top" align="left">Overall</td>
<td valign="top" align="center">1.16 (0.93, 1.45)</td>
<td valign="top" align="center">0.186</td>
<td valign="top" align="center">66.9&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Hyperuricemia</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
</tr>
<tr>
<td valign="top" align="left">No</td>
<td valign="top" align="center">1.24 (0.79,1.95)</td>
<td valign="top" align="center">0.351</td>
<td valign="top" align="center">76.6&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Yes</td>
<td valign="top" align="center">1.17 (0.61, 2.26)</td>
<td valign="top" align="center">0.635</td>
<td valign="top" align="center">81.3&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">LVEF</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
</tr>
<tr>
<td valign="top" align="left">&#x2265;45&#x0025;</td>
<td valign="top" align="center">0.97 (0.84, 1.13)</td>
<td valign="top" align="center">0.687</td>
<td valign="top" align="center">0.0&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">&#x2265;50&#x0025;</td>
<td valign="top" align="center">1.34 (0.92, 1.97)</td>
<td valign="top" align="center">0.128</td>
<td valign="top" align="center">71.1&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Uric acid-lowering drugs</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
</tr>
<tr>
<td valign="top" align="left">Traditional</td>
<td valign="top" align="center">1.66 (1.20, 2.28)</td>
<td valign="top" align="center">0.002</td>
<td valign="top" align="center">0.0&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Novel</td>
<td valign="top" align="center">0.99 (0.89, 1.11)</td>
<td valign="top" align="center">0.877</td>
<td valign="top" align="center">0.0&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left" rowspan="10">HF hospitalization</td>
<td valign="top" align="left">Overall</td>
<td valign="top" align="center">0.85 (0.79, 0.91)</td>
<td valign="top" align="center">&#x003C;0.001</td>
<td valign="top" align="center">0.0&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Hyperuricemia</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
</tr>
<tr>
<td valign="top" align="left">No</td>
<td valign="top" align="center">0.85 (0.78, 0.92)</td>
<td valign="top" align="center">&#x003C;0.001</td>
<td valign="top" align="center">0.0&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Yes</td>
<td valign="top" align="center">0.83 (0.73, 0.94)</td>
<td valign="top" align="center">0.003</td>
<td valign="top" align="center">0.0&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">LVEF</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
</tr>
<tr>
<td valign="top" align="left">&#x2265;45&#x0025;</td>
<td valign="top" align="center">0.86 (0.79, 0.94)</td>
<td valign="top" align="center">&#x003C;0.001</td>
<td valign="top" align="center">0.0&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">&#x2265;50&#x0025;</td>
<td valign="top" align="center">0.81 (0.72, 1.18)</td>
<td valign="top" align="center">0.002</td>
<td valign="top" align="center">0.0&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Uric acid-lowering drugs</td>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
<td valign="top" align="center"/>
</tr>
<tr>
<td valign="top" align="left">Traditional</td>
<td valign="top" align="center">0.85 (0.78, 0.92)</td>
<td valign="top" align="center">&#x003C;0.001</td>
<td valign="top" align="center">0.0&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Novel</td>
<td valign="top" align="center">0.83 (0.73, 0.94)</td>
<td valign="top" align="center">0.003</td>
<td valign="top" align="center">0.0&#x0025;</td>
</tr>
<tr>
<td valign="top" align="left">Change in KCCQ clinical summary score</td>
<td valign="top" align="left">Overall</td>
<td valign="top" align="center">1.96 (&#x2212;0.91, 4.84)</td>
<td valign="top" align="center">0.181</td>
<td valign="top" align="center">60.3&#x0025;</td>
</tr>
</tbody>
</table>
<table-wrap-foot>
<fn id="table-fn4"><p>HFpEF, heart failure with preserved ejection fraction; HF, heart failure; RR, relative risk; HR, hazard ratio; WMD, weighted mean difference; LVEF, left ventricular ejection fraction; KCCQ: Kansas City cardiomyopathy questionnaire.</p></fn>
</table-wrap-foot>
</table-wrap>
</sec>
<sec id="s3e2"><title>Experimental vs. control (HR)</title>
<p>The association between uric acid-lowering therapy and all-cause mortality in patients with HFpEF (HR) was analyzed in 4 studies. The heterogeneity testing resulted in an <italic>I</italic><sup>2</sup> of 66.9&#x0025;, leading to the adoption of a random-effects model. The results indicated that uric acid-lowering therapy did not significantly reduce the risk of all-cause mortality (HR: 1.16, 95&#x0025; CI: 0.93&#x2013;1.45, <italic>P&#x2009;</italic>&#x003D;&#x2009;0.186) (<xref ref-type="fig" rid="F5">Figure&#x00A0;5B</xref>, <xref ref-type="table" rid="T4">Table&#x00A0;4</xref>). Subgroup analysis revealed that only when uric acid-lowering medication was of the traditional type did the treatment increase the risk of all-cause mortality (HR:1.66, 95&#x0025; CI: 1.20&#x2013;2.28, <italic>P&#x2009;</italic>&#x003D;&#x2009;0.002) (<xref ref-type="table" rid="T4">Table&#x00A0;4</xref>).</p>
</sec>
</sec>
<sec id="s3f"><title>Meta-analysis of the association between uric acid-lowering therapy and CV mortality in patients with HFpEF</title>
<p>Two studies were included to assess the association between uric acid-lowering therapy and CV mortality in patients with HFpEF. Heterogeneity testing showed an <italic>I</italic><sup>2</sup> of 0.0&#x0025;, which led to the use of a fixed-effect model for analysis. The result indicated that uric acid-lowering therapy did not significantly improve the outcome of CV mortality (RR: 0.92, 95&#x0025; CI: 0.80&#x2013;1.07, <italic>P&#x2009;</italic>&#x003D;&#x2009;0.274) (<xref ref-type="fig" rid="F6">Figure&#x00A0;6</xref>, <xref ref-type="table" rid="T4">Table&#x00A0;4</xref>).</p>
<fig id="F6" position="float"><label>Figure 6</label>
<caption><p>Meta-analysis of the association between uric acid-lowering therapy and CV mortality in patients with HFpEF.</p></caption>
<graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="fcvm-11-1403242-g006.tif"/>
</fig>
</sec>
<sec id="s3g"><title>Meta-analysis of the association between uric acid-lowering therapy and HF hospitalization in patients with HFpEF</title>
<p>A total of three studies were included to assess the association between uric acid-lowering therapy and HF hospitalization in patients with HFpEF. Heterogeneity testing revealed an <italic>I</italic><sup>2</sup> of 0.0&#x0025;, hence a fixed-effect model was employed for analysis. The results suggested that uric acid-lowering therapy was associated with a lower risk of HF hospitalization (RR: 0.85, 95&#x0025; CI: 0.79&#x2013;0.91, <italic>P&#x2009;</italic>&#x003C;&#x2009;0.001) (<xref ref-type="fig" rid="F7">Figure&#x00A0;7</xref>, <xref ref-type="table" rid="T4">Table&#x00A0;4</xref>). Subgroup analyses based on the presence of hyperuricemia, LVEF, and the type of uric acid-lowering therapy also yielded consistent results (<xref ref-type="table" rid="T4">Table&#x00A0;4</xref>).</p>
<fig id="F7" position="float"><label>Figure 7</label>
<caption><p>Meta-analysis of the association between uric acid-lowering therapy and HF hospitalization in patients with HFpEF.</p></caption>
<graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="fcvm-11-1403242-g007.tif"/>
</fig>
</sec>
<sec id="s3h"><title>Meta-analysis of the association between uric acid-lowering therapy and change in KCCQ clinical summary score</title>
<p>The analysis incorporated two studies to assess the association between uric acid-lowering therapy and change in KCCQ clinical summary score. Heterogeneity testing indicated an <italic>I</italic><sup>2</sup> of 60.3&#x0025;, leading to the use of a random-effects model for the analysis. The results indicated that there was no significant difference in the change of the KCCQ clinical summary score between the uric acid-lowering therapy group and the control group (WMD: 1.964, 95&#x0025; CI: &#x2212;0.913 to 4.842, <italic>P&#x2009;</italic>&#x003D;&#x2009;0.181) (<xref ref-type="fig" rid="F8">Figure&#x00A0;8</xref>, <xref ref-type="table" rid="T4">Table&#x00A0;4</xref>).</p>
<fig id="F8" position="float"><label>Figure 8</label>
<caption><p>Meta-analysis of the association between uric acid-lowering therapy and change in KCCQ clinical summary score.</p></caption>
<graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="fcvm-11-1403242-g008.tif"/>
</fig>
</sec>
<sec id="s3i"><title>Sensitivity analysis</title>
<p>Sensitivity analysis in our study demonstrated the robustness of our findings. By systematically excluding certain studies and re-evaluating the effect estimates, we have ensured that our conclusions were not unduly influenced by any single study or potential biases. This rigorous examination of our data strengthens the reliability of our results and provides confidence in the validity of our research (<xref ref-type="table" rid="T4">Table&#x00A0;4</xref>).</p>
</sec>
</sec>
<sec id="s4" sec-type="discussion"><title>Discussion</title>
<p>This study incorporated 12 eligible articles to separately explore the associations of serum uric acid levels and uric acid-lowering therapy with the prognosis of patients with HFpEF. The findings of this study reveal that elevated serum uric acid levels were consistently associated with an increased risk of all-cause mortality and CV mortality in HFpEF patients. Subgroup analyses further confirmed the association between serum uric acid levels and all-cause mortality, especially in non-Asian populations, those with chronic HFpEF, and when the follow-up duration was two years or longer. An increase in uric acid levels was also associated with an increased risk of hospitalization due to HF [hazard ratio (HR)]. In terms of therapeutic interventions, uric acid-lowering therapy did not significantly reduce mortality in patients with HFpEF. Nevertheless, uric acid-lowering therapy was associated with a reduced risk of HF hospitalization, indicating a potential benefit in managing this aspect of HFpEF prognosis.</p>
<p>Previous studies have illuminated that serum uric acid stands as a distinctive risk factor for HF and prognosis of HF (<xref ref-type="bibr" rid="B31">31</xref>&#x2013;<xref ref-type="bibr" rid="B36">36</xref>). In a large Italian cohort, serum uric acid was an independent risk factor for all HF and fatal HF (<xref ref-type="bibr" rid="B31">31</xref>). A study conducted in Japan showed that elevated uric acid levels were associated with a higher incidence of the primary endpoint and rehospitalization owing to acute decompensated HF (<xref ref-type="bibr" rid="B32">32</xref>). Cicero et al. (<xref ref-type="bibr" rid="B33">33</xref>) found that hyperuricemia is an emerging risk factor in the pathogenesis of HF and is intricately linked to a bleaker prognosis in HF patients. In a meta-analysis, the author found that elevated serum uric acid levels independently predicted all-cause mortality and the combined endpoint of death or readmission in acute HF patients (<xref ref-type="bibr" rid="B34">34</xref>). In the study by Coiro et al., Elevated serum uric acid concentrations have incremental prognostic value in elderly patients with acute HF, regardless of etiology and systolic function (<xref ref-type="bibr" rid="B36">36</xref>). The result from a comprehensive meta-analysis revealed that higher serum uric acid levels were associated with an increased risk of all-cause mortality, cardiac death, and HF rehospitalization in HF patients (<xref ref-type="bibr" rid="B15">15</xref>). However, the prognostic value of serum uric acid level in patients with HFpEF has not been fully elucidated. Our findings indicate that elevated serum uric acid levels were associated with an increased risk of all-cause, CV mortality, and HF hospitalization in patients with HFpEF. In a study investigating whether serum uric acid level on admission could be associated with subsequent mortality in hospitalized patients with HFpEF, higher admission serum uric acid was an independent determinant of mortality in hospitalized HFpEF patients (<xref ref-type="bibr" rid="B25">25</xref>). In the study by Nishino et al. (<xref ref-type="bibr" rid="B21">21</xref>), uric acid was a predictor for the composite of all-cause death and HF re-hospitalization in patients with hyperuricemia and HFpEF. In hospitalized elderly patients with chronic HF, serum uric acid was an independent predictor of adverse outcomes, which can be seen in HFmrEF patients (<xref ref-type="bibr" rid="B37">37</xref>). In a study involving 210 patients with HFpEF, elevated serum uric acid was significantly associated with the HF readmission rate in patients with HFpEF (<xref ref-type="bibr" rid="B24">24</xref>). In a study conducted in China, uric acid level was associated with HF readmission in patients with HFpEF (<xref ref-type="bibr" rid="B38">38</xref>). Our findings suggest that elevated serum uric acid levels serve as a significant prognostic marker in patients with HFpEF, indicating a potential role in the pathophysiology of the disease and its clinical outcomes.</p>
<p>Several insights into the potential mechanisms by which lowering uric acid levels may improve outcomes in patients with HF were provided by previous studies. A systemic proinflammatory state induced by comorbidities, including hyperuricemia, could cause myocardial structural and functional alterations (<xref ref-type="bibr" rid="B39">39</xref>). Furthermore, elevated uric acid levels can trigger a systemic inflammatory response, predisposing to comorbidities such as infections and malignancies, which significantly contribute to the mortality rate in HFpEF (<xref ref-type="bibr" rid="B40">40</xref>). Elevated uric acid may lead to increased cytokine activation, insulin resistance and oxidative stress, impair endothelial function and activate the renin-angiotensin system (<xref ref-type="bibr" rid="B41">41</xref>&#x2013;<xref ref-type="bibr" rid="B44">44</xref>). Uric acid may also directly contribute to HF worsening by elevating blood pressure (<xref ref-type="bibr" rid="B45">45</xref>), and reducing renal function (<xref ref-type="bibr" rid="B46">46</xref>).</p>
<p>In addition, HFpEF patients varied by LVEF have different clinical characteristics, prognosis, and treatment response (<xref ref-type="bibr" rid="B47">47</xref>, <xref ref-type="bibr" rid="B48">48</xref>). In this study, HFpEF patients had differences in LVEF. Although the patients we included was mostly elderly, the age distribution was not uniform. Age-related mechanisms play an important role in the pathophysiology of HFpEF (<xref ref-type="bibr" rid="B49">49</xref>). Older patients are at higher risk of side effects from HF medications (<xref ref-type="bibr" rid="B50">50</xref>). The proportion of men and women in the studies we included was fairly evenly distributed. A previous study found that hyperuricemia was associated with HF readmission in all patients, especially men (<xref ref-type="bibr" rid="B24">24</xref>). This is consistent with the higher comorbidities burden in men with HF (<xref ref-type="bibr" rid="B51">51</xref>). The observed differences may suggest that the impact of serum uric acid levels in patients with HFpEF requires a more personalized approach, taking into account the specific conditions of each patient.</p>
<p>In this meta-analysis, the administration of uric acid-lowering therapy did not yield a statistically significant reduction in mortality rates among patients afflicted with HFpEF. However, it was observed that uric acid-lowering therapy was correlated with a decreased risk of HF hospitalization. A systematic review and meta-analysis of RCTs showed that uric acid-lowering therapies did not improve all-cause mortality and CV death in HF patients (<xref ref-type="bibr" rid="B52">52</xref>). A recent meta-analysis suggested that targeting uric acid-lowering as a therapeutic intervention did not improve the prognosis of patients with HF (<xref ref-type="bibr" rid="B15">15</xref>). However, a study enrolling patients with HFpEF from the Prospective Multicenter Observational Study of Patients With Heart Failure With Preserved Ejection Fraction (PURSUIT-HFpEF) registry suggested that comprehensive interventions for lowering uric acid, including the use of urate-lowering therapy, in patients with hyperuricemia and HFpEF can have an effect of beneficial prognosis (<xref ref-type="bibr" rid="B21">21</xref>). The conflicting results of these findings may be attributed to differences in uric acid-lowering therapies. In the study by Suzuki et al. (<xref ref-type="bibr" rid="B53">53</xref>), febuxostat was potentially more effective than allopurinol for treating patients with chronic HF and hyperuricemia. These findings suggest that while uric acid-lowering therapy may not improve mortality rates in HFpEF in this study, it could still play a role in managing the disease. Further research, including well-designed clinical trials, is needed to determine the impact of lowering uric acid therapies in patients with HFpEF.</p>
<p>The importance of our research lies in the following aspects. Firstly, this study underscores the importance of monitoring serum uric acid levels in patients with HFpEF as a marker for early identification of those at risk for adverse outcomes. By regularly assessing serum uric acid levels, clinicians can identify high-risk patients earlier and adjust treatment strategies promptly to prevent potential adverse outcomes. Secondly, the meta-analysis provides new guidance for clinical practice, suggesting that physicians should consider serum uric acid levels as a factor in management and treatment decisions for HFpEF patients. This may include more aggressive interventions for patients with hyperuricemia to mitigate the risk of adverse outcomes. Thirdly, the study also sets the stage for future research by exploring whether lowering serum uric acid levels could offer additional benefits for HFpEF patients and how personalized treatment plans can minimize the adverse outcomes of HF. This could involve larger-scale clinical trials to validate the efficacy of uric acid-lowering therapy and to determine the optimal therapeutic approaches and timing for such interventions.</p>
<p>The strengths of our study include several key aspects: Firstly, it is the first meta-analysis to explore the association between adverse outcomes and uric acid-lowering therapy in patients with HFpEF. Secondly, the study incorporated a substantial sample size from high-quality literature, which lends a degree of reliability and stability to the findings. Thirdly, subgroup analyses were conducted on outcomes related to all-cause mortality and HF hospitalization, stratifying the study population based on the presence of hyperuricemia, the defined range of LVEF, and the type of uric acid-lowering therapy used. However, there are limitations to consider: Firstly, initially, angiotensin receptor neprilysin inhibitors (ARNi) and SGLT2i are not specifically developed to lower uric acid levels. It is plausible that the amelioration of HF symptoms could secondarily result in decreased uric acid levels, as the resolution of HF can lead to improved renal function and reduced uric acid retention (<xref ref-type="bibr" rid="B54">54</xref>). Consequently, discerning whether the observed enhancements in HF prognosis are attributable to the direct pharmacological action of these drugs, or indirectly due to the amelioration of HF and its associated metabolic changes, remains a challenge. Secondly, there were different thresholds for defining hyperuricemia and hypouricemia across studies, which may influence the results and may be one of the sources of heterogeneity in the outcome measures. Thirdly, the limited number of studies reporting on certain outcomes may affect the stability of the findings. Fourth, our meta-analysis is unable to perform a formal assessment of publication bias using funnel plots for the outcomes evaluated. Commonly, funnel plots are utilized to detect potential publication bias when a sufficient number of studies&#x2014;typically ten or more are available for an outcome. This graphical method aids in visualizing the distribution of study results and identifying any asymmetry that may suggest selective reporting or publication of results. In our analysis, each outcome was represented by fewer than ten studies, which limits the reliability of funnel plot analysis to detect publication bias. These limitations should be taken into account when interpreting the results and when designing future research to further investigate the role of uric acid levels and uric acid-lowering therapy in HFpEF patients.</p>
</sec>
<sec id="s5" sec-type="conclusions"><title>Conclusion</title>
<p>In summary, these results underscore the importance of serum uric acid levels in the prognosis of HFpEF and the potential utility of uric acid-lowering therapy in reducing HF hospitalization, while also highlighting the need for further research to clarify whether interventions targeting hyperuricemia can confer benefits to HFpEF patients.</p>
</sec>
</body>
<back>
<sec id="s6" sec-type="data-availability"><title>Data availability statement</title>
<p>The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.</p>
</sec>
<sec id="s7" sec-type="author-contributions"><title>Author contributions</title>
<p>LL: Conceptualization, Methodology, Project administration, Supervision, Writing &#x2013; original draft. YC: Data curation, Formal Analysis, Investigation, Methodology, Writing &#x2013; review &#x0026; editing. FL: Data curation, Formal Analysis, Investigation, Methodology, Writing &#x2013; review &#x0026; editing. YY: Conceptualization, Supervision, Writing &#x2013; original draft, Writing &#x2013; review &#x0026; editing.</p>
</sec>
<sec id="s8" sec-type="funding-information"><title>Funding</title>
<p>The author(s) declare that no financial support was received for the research, authorship, and/or publication of this article.</p>
</sec>
<sec id="s9" sec-type="COI-statement"><title>Conflict of interest</title>
<p>The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.</p>
</sec>
<sec id="s11" sec-type="disclaimer"><title>Publisher&#x0027;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>
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<sec id="s10" sec-type="supplementary-material"><title>Supplementary material</title>
<p>The Supplementary Material for this article can be found online at: <ext-link ext-link-type="uri" xlink:href="https://www.frontiersin.org/articles/10.3389/fcvm.2024.1403242/full#supplementary-material">https://www.frontiersin.org/articles/10.3389/fcvm.2024.1403242/full&#x0023;supplementary-material</ext-link></p>
<supplementary-material id="SD1" content-type="local-data">
<media mimetype="application" mime-subtype="vnd.openxmlformats-officedocument.wordprocessingml.document" xlink:href="Table1.docx"/>
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