{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,15]],"date-time":"2026-07-15T13:04:45Z","timestamp":1784120685499,"version":"3.55.0"},"reference-count":14,"publisher":"BMJ","issue":"3","license":[{"start":{"date-parts":[[2026,7,15]],"date-time":"2026-07-15T00:00:00Z","timestamp":1784073600000},"content-version":"unspecified","delay-in-days":14,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100017268","name":"Berlin Institute of Health","doi-asserted-by":"crossref","id":[{"id":"10.13039\/501100017268","id-type":"DOI","asserted-by":"crossref"}]},{"DOI":"10.13039\/100015661","name":"UCB Pharma","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100015661","id-type":"DOI","asserted-by":"publisher"}]},{"name":"German Federal Ministry of Education and Research"},{"name":"Eli Lilly"},{"DOI":"10.13039\/100004331","name":"Johnson&Johnson","doi-asserted-by":"crossref","id":[{"id":"10.13039\/100004331","id-type":"DOI","asserted-by":"crossref"}]},{"DOI":"10.13039\/100006483","name":"AbbVie","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100006483","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["RMD Open"],"accepted":{"date-parts":[[2026,6,13]]},"published-print":{"date-parts":[[2026,7]]},"abstract":"<jats:sec>\n                    <jats:title>Objectives<\/jats:title>\n                    <jats:p>To investigate the impact of vitamin D on disease activity, function and health in patients with radiographic axial spondyloarthritis (r-axSpA) undergoing biological disease-modifying antirheumatic drug (bDMARD) therapy.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Patients with r-axSpA and active disease at baseline initiating a bDMARD were included in this analysis. Vitamin D (25-hydroxyvitamin D) was measured at baseline and every 6\u2009months until year 2; deficiency was defined as &lt;20\u2009ng\/mL. The outcomes were AxSpA Disease Activity Score (ASDAS), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Patient Global Assessment (PGA), Bath Ankylosing Spondylitis Functional Index (BASFI), Assessment of SpondyloArthritis international Society Health Index (ASAS-HI) and C reactive protein (CRP). Longitudinal associations were evaluated using generalised estimating equations, with sensitivity analyses accounting for time-varying confounders.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>We analysed 122 patients (mean age 36.6 (10.3) years; 66.4% male), of whom 53.3% had vitamin D deficiency at baseline. In longitudinal models, normal vitamin D levels were associated with lower ASDAS (\u03b2 per 1\u2009ng\/mL increase: \u22120.010; 95%\u2009CI \u22120.017 to \u22120.003), BASDAI (\u03b2: \u22120.021; 95%\u2009CI \u22120.036 to \u22120.006), PGA (\u03b2: \u22120.021; 95%\u2009CI \u22120.039 to \u22120.003) and BASFI (\u03b2: \u22120.015; 95%\u2009CI \u22120.032 to 0.001). Effect estimates of ASDAS, BASDAI, BASFI, CRP (and their corresponding categorical outcomes) were attenuated in sensitivity analyses but remained directionally consistent. Positive associations with PGA and ASAS-HI were also observed though the estimates were not consistent through all models.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>Normal vitamin D levels were modestly associated with lower disease activity in r-axSpA treated with bDMARDs. Monitoring and optimising vitamin D status may support better disease control.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1136\/rmdopen-2026-006921","type":"journal-article","created":{"date-parts":[[2026,7,15]],"date-time":"2026-07-15T12:10:39Z","timestamp":1784117439000},"page":"e006921","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":0,"title":["Impact of vitamin D levels on disease activity, function and health over 2 years in radiographic axial spondyloarthritis: data from GErman SPondyloarthritis Inception Cohort (GESPIC)"],"prefix":"10.1136","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4600-9484","authenticated-orcid":false,"given":"Murat","family":"Torgutalp","sequence":"first","affiliation":[{"name":"Department of Gastroenterology, Infectiology and Rheumatology (Including Nutrition Medicine), Charite Universitatsmedizin Berlin, Berlin, Germany"},{"name":"Department of Rheumatology and Clinical Immunology, Charit\u00e9 - Universit\u00e4tsmedizin Berlin, Corporate Member of Freie Universit\u00e4t Berlin and Humboldt-Universit\u00e4t zu Berlin, Berlin, Germany"},{"name":"Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Berlin, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4306-033X","authenticated-orcid":false,"given":"Fabian","family":"Proft","sequence":"additional","affiliation":[{"name":"Department of Gastroenterology, Infectiology and Rheumatology (Including Nutrition Medicine), Charite Universitatsmedizin Berlin, Berlin, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hildrun","family":"Haibel","sequence":"additional","affiliation":[{"name":"Department of Gastroenterology, Infectiology and Rheumatology (Including Nutrition Medicine), Charite Universitatsmedizin Berlin, Berlin, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Henriette","family":"Baum","sequence":"additional","affiliation":[{"name":"Department of Gastroenterology, Infectiology and Rheumatology (Including Nutrition Medicine), Charite Universitatsmedizin Berlin, Berlin, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marina","family":"D\u2019Urso","sequence":"additional","affiliation":[{"name":"Department of Molecular Metabolism and Precision Nutrition, German Institute of Human Nutrition Potsdam-Rehbruecke, Potsdam, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Caroline","family":"H\u00f6ppner","sequence":"additional","affiliation":[{"name":"Department of Gastroenterology, Infectiology and Rheumatology (Including Nutrition Medicine), Charite Universitatsmedizin Berlin, Berlin, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4840-5069","authenticated-orcid":false,"given":"Mikhail","family":"Protopopov","sequence":"additional","affiliation":[{"name":"Department of Gastroenterology, Infectiology and Rheumatology (Including Nutrition Medicine), Charite Universitatsmedizin Berlin, Berlin, Germany"},{"name":"Berlin Institute of Health (BIH), Berlin, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7442-2570","authenticated-orcid":false,"given":"Judith","family":"Rademacher","sequence":"additional","affiliation":[{"name":"Department of Gastroenterology, Infectiology and Rheumatology (Including Nutrition Medicine), Charite Universitatsmedizin Berlin, Berlin, Germany"},{"name":"Berlin Institute of Health (BIH), Berlin, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Didem","family":"Sahin","sequence":"additional","affiliation":[{"name":"Department of Gastroenterology, Infectiology and Rheumatology (Including Nutrition Medicine), Charite Universitatsmedizin Berlin, Berlin, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Denis","family":"Poddubnyy","sequence":"additional","affiliation":[{"name":"Department of Gastroenterology, Infectiology and Rheumatology (Including Nutrition Medicine), Charite Universitatsmedizin Berlin, Berlin, Germany"},{"name":"Division of Rheumatology, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada"},{"name":"Division of Rheumatology, Schroeder Arthritis Institute, University Health Network, Toronto, Ontario, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5612-043X","authenticated-orcid":false,"given":"Valeria","family":"Rios Rodriguez","sequence":"additional","affiliation":[{"name":"Department of Gastroenterology, Infectiology and Rheumatology (Including Nutrition Medicine), Charite Universitatsmedizin Berlin, Berlin, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"239","published-online":{"date-parts":[[2026,7,15]]},"reference":[{"key":"2026071505102298000_12.3.e006921.1","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(16)31591-4"},{"key":"2026071505102298000_12.3.e006921.2","doi-asserted-by":"crossref","first-page":"309","DOI":"10.1038\/s41584-025-01254-5","article-title":"Understanding the causes of treatment failure is crucial for the management of axial spondyloarthritis","volume":"21","author":"Poddubnyy","year":"2025","journal-title":"Nat Rev Rheumatol"},{"key":"2026071505102298000_12.3.e006921.3","doi-asserted-by":"publisher","DOI":"10.1038\/ncprheum0855"},{"key":"2026071505102298000_12.3.e006921.4","first-page":"827","article-title":"Vitamin D level in rheumatoid arthritis and its correlation with the disease activity: a meta-analysis","volume":"34","author":"Lee","year":"2016","journal-title":"Clin Exp Rheumatol"},{"key":"2026071505102298000_12.3.e006921.5","doi-asserted-by":"crossref","DOI":"10.1186\/s41927-021-00223-1","article-title":"Vitamin D supplementation in systemic lupus erythematosus: relationship to disease activity, fatigue and the interferon signature gene expression","volume":"5","author":"Magro","year":"2021","journal-title":"BMC Rheumatol"},{"key":"2026071505102298000_12.3.e006921.6","doi-asserted-by":"crossref","first-page":"388","DOI":"10.5114\/reum.2018.80717","article-title":"Vitamin D serum concentration is not related to the activity of spondyloarthritis - preliminary study","volume":"56","author":"Gu\u0142a","year":"2018","journal-title":"Reumatologia"},{"key":"2026071505102298000_12.3.e006921.7","doi-asserted-by":"crossref","first-page":"2027","DOI":"10.1007\/s00198-016-3489-7","article-title":"The vitamin D status in ankylosing spondylitis in relation to intestinal inflammation, disease activity, and bone health: a cross-sectional study","volume":"27","author":"Klingberg","year":"2016","journal-title":"Osteoporos Int"},{"key":"2026071505102298000_12.3.e006921.8","first-page":"210","article-title":"Vitamin D status in spondyloarthritis: results of the ASAS-COMOSPA international study","volume":"36","author":"Fernandes","year":"2018","journal-title":"Clin Exp Rheumatol"},{"key":"2026071505102298000_12.3.e006921.9","first-page":"396","article-title":"Vitamin D, disease activity and comorbidities in early spondyloarthritis","volume":"34","author":"Hmamouchi","year":"2016","journal-title":"Clin Exp 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