{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T04:16:57Z","timestamp":1787026617394,"version":"build-2736575974"},"reference-count":35,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,6,22]],"date-time":"2026-06-22T00:00:00Z","timestamp":1782086400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Med."],"abstract":"<jats:sec>\n                    <jats:title>Introduction<\/jats:title>\n                    <jats:p>Classification of axial psoriatic arthritis (ax-PsA) within existing spondyloarthritis (SpA) criteria remains unclear. To clarify this issue, we compared the clinical features of ax-PsA and axial SpA (ax-SpA).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>\n                      In this systematic review and meta-analysis, we searched six databases (PubMed, Web of Science, Cochrane Library, Ovid, Scopus, and Embase) and one trial registry (\n                      <jats:ext-link>ClinicalTrials.gov<\/jats:ext-link>\n                      ) for studies published from inception to April 20, 2025, without language restrictions. Observational studies comparing ax-PsA and ax-SpA were included. Meta-analyses were conducted to evaluate disease activity scores, spinal function scores, inflammatory markers, and HLA-B27 positivity.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      Fifteen studies including 2,704 patients with ax-PsA and 9,248 with ax-SpA from diverse global populations were analyzed. Meta-analysis showed no significant differences between ax-PsA and ax-SpA in the Bath Ankylosing Spondylitis Disease Activity Index, Ankylosing Spondylitis Disease Activity Score, Bath Ankylosing Spondylitis Functional Index, or C-reactive protein levels. However, ax-PsA was associated with significantly lower HLA-B27 positivity compared with ax-SpA (risk ratio, 0.37; 95% confidence interval [CI], 0.32\u20130.43;\n                      <jats:italic>p<\/jats:italic>\n                      &amp;lt; 0.001). In subgroup analyses, ax-PsA demonstrated modestly better BASFI scores than ankylosing spondylitis (mean difference, \u22120.35; 95% CI, \u22120.64\u2013\u22120.05;\n                      <jats:italic>p<\/jats:italic>\n                      = 0.022).\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>The marked difference in HLA-B27 positivity between ax-PsA and ax-SpA supports their distinction as separate disease entities. Similar disease activity and functional outcomes suggest shared downstream inflammatory pathways. The lower HLA-B27 positivity in ax-PsA may reflect alternative mechanisms of interleukin (IL)-23\/IL-17 axis activation, with potential therapeutic implications. Clinical differentiation should incorporate HLA-B27 testing and imaging. Future research should focus on disease course variability and subgroup-specific characteristics.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Systematic review registration<\/jats:title>\n                    <jats:p>\n                      <jats:ext-link>https:\/\/www.crd.york.ac.uk\/PROSPERO\/view\/CRD420251043651<\/jats:ext-link>\n                      , identifier: CRD420251043651.\n                    <\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fmed.2026.1856665","type":"journal-article","created":{"date-parts":[[2026,6,22]],"date-time":"2026-06-22T04:36:55Z","timestamp":1782103015000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":1,"title":["Differences in clinical features between axial psoriatic arthritis and axial spondyloarthritis: a systematic review and meta-analysis of observational studies"],"prefix":"10.3389","volume":"13","author":[{"given":"Zhihao","family":"Qiu","sequence":"first","affiliation":[{"name":"The Second School of Clinical Medicine, Zhejiang Chinese Medical University","place":["Hangzhou, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zijie","family":"Chen","sequence":"additional","affiliation":[{"name":"The First School of Clinical Medicine, Zhejiang Chinese Medical University","place":["Hangzhou, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zhe","family":"Yang","sequence":"additional","affiliation":[{"name":"The Second School of Clinical Medicine, Zhejiang Chinese Medical University","place":["Hangzhou, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ruibo","family":"Xia","sequence":"additional","affiliation":[{"name":"The Second School of Clinical Medicine, Zhejiang Chinese Medical University","place":["Hangzhou, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Weikai","family":"Chen","sequence":"additional","affiliation":[{"name":"The First School of Clinical Medicine, Zhejiang Chinese Medical University","place":["Hangzhou, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuwei","family":"Zhu","sequence":"additional","affiliation":[{"name":"Department of Nephrology and Rheumatology, Zhejiang Chinese Medical University, Pingyang Hospital of Traditional Chinese Medicine (Pingyang County Hospital of Traditional Chinese Medicine)","place":["Pingyang, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Weijie","family":"Wang","sequence":"additional","affiliation":[{"name":"Rheumatology and Immunology Department, The Second Affiliated Hospital of Zhejiang Chinese Medical University (Xinhua Hospital of Zhejiang Province)","place":["Hangzhou, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zhengfu","family":"Li","sequence":"additional","affiliation":[{"name":"Rheumatology and Immunology Department, The Second Affiliated Hospital of Zhejiang Chinese Medical University (Xinhua Hospital of Zhejiang Province)","place":["Hangzhou, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kepeng","family":"Yang","sequence":"additional","affiliation":[{"name":"Rheumatology and Immunology Department, The Second Affiliated Hospital of Zhejiang Chinese Medical University (Xinhua Hospital of Zhejiang Province)","place":["Hangzhou, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,6,22]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"65","DOI":"10.7861\/clinmedicine.17-1-65","article-title":"Psoriatic arthritis: state of the art review","volume":"17","author":"Coates","year":"2017","journal-title":"Clin 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