{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,16]],"date-time":"2026-06-16T12:58:00Z","timestamp":1781614680010,"version":"3.54.5"},"reference-count":35,"publisher":"BMJ","issue":"2","license":[{"start":{"date-parts":[[2026,6,16]],"date-time":"2026-06-16T00:00:00Z","timestamp":1781568000000},"content-version":"unspecified","delay-in-days":76,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"funder":[{"DOI":"10.13039\/100004312","name":"Eli Lilly and Company","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100004312","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["RMD Open"],"accepted":{"date-parts":[[2026,6,3]]},"published-print":{"date-parts":[[2026,4]]},"abstract":"<jats:sec>\n                    <jats:title>Objectives<\/jats:title>\n                    <jats:p>To study the impact of C reactive protein (CRP) level at treatment start on interleukin-17 inhibitor (IL-17i) and tumour necrosis factor inhibitor (TNFi) effectiveness, including treatment retention, in axial spondyloarthritis (axSpA).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Nationwide observational study including patients with axSpA from the DANBIO registry initiating their first IL-17i or first TNFi between 2015 and 2024. Outcomes were 12-month treatment retention and Bath Ankylosing Spondylitis Disease Activity Index remission stratified by CRP levels (&lt;5 (low)\/5\u201310 (intermediate)\/&gt;10 mg\/L (high)) at treatment initiation (baseline). Kaplan-Meier plots (including substratification by sex and radiographic status) and Cox regression models were used to assess treatment retention and hazard of discontinuation for IL-17i and TNFi separately.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>Overall, 3387 patients were included (601 IL-17i, 2786 TNFi) with baseline CRP levels (low\/intermediate\/high) 57%\/17%\/26% for IL-17i and 48%\/20%\/32% for TNFi. For IL-17i, 95% of patients were TNFi-experienced; for TNFi, 99% were biologic-na\u00efve.<\/jats:p>\n                    <jats:p>The 12-month retention rates stratified by baseline CRP (low\/intermediate\/high) were 51%\/53%\/55% for IL-17i and 63%\/66%\/72% for TNFi, with similar results when stratified by sex and radiographic status. Cox models (reference: low CRP) showed no clear association between CRP level and treatment retention among patients receiving IL-17i (intermediate CRP: HR 0.96, 95% CI 0.68 to 1.19; high CRP: HR 0.90, 95% CI 0.68 to 1.19). In contrast, among patients receiving TNFi, intermediate and high CRP levels were associated with a lower risk of treatment discontinuation (HR 0.86, 95% CI 0.73 to 1.02 and HR 0.72, 95% CI 0.62 to 0.84, respectively). Remission rates were 6%\/8%\/11% for IL-17i and 19%\/22%\/32% for TNFi.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>In routine care, IL-17i was mainly used in biologic-experienced patients, whereas TNFi was primarily used in biologic-na\u00efve patients with axSpA. Higher baseline CRP levels were associated with higher retention for first TNFi but not for first IL-17i. Higher CRP was associated with higher remission rates for both IL-17i and TNFi.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1136\/rmdopen-2026-006807","type":"journal-article","created":{"date-parts":[[2026,6,16]],"date-time":"2026-06-16T12:27:23Z","timestamp":1781612843000},"page":"e006807","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":0,"title":["Impact of C reactive protein on effectiveness of interleukin-17 and tumour necrosis factor inhibitors in axial spondyloarthritis: a Danish nationwide observational study"],"prefix":"10.1136","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0009-0000-8778-3359","authenticated-orcid":false,"given":"Annemette","family":"H\u00f8egh Pedersen","sequence":"first","affiliation":[{"name":"Center for Rheumatology and Spine Diseases, Rigshospitalet, Glostrup, Denmark"},{"name":"Copenhagen Center for Arthritis Research and the DANBIO Registry, Rigshospitalet, Copenhagen, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4232-6079","authenticated-orcid":false,"given":"Kasper Yde","family":"Jensen","sequence":"additional","affiliation":[{"name":"Center for Rheumatology and Spine Diseases, Rigshospitalet, Glostrup, Denmark"},{"name":"Copenhagen Center for Arthritis Research and the DANBIO Registry, Rigshospitalet, Copenhagen, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4229-6818","authenticated-orcid":false,"given":"Merete Lund","family":"Hetland","sequence":"additional","affiliation":[{"name":"Center for Rheumatology and Spine Diseases, Rigshospitalet, Glostrup, Denmark"},{"name":"Copenhagen Center for Arthritis Research and the DANBIO Registry, Rigshospitalet, Copenhagen, Denmark"},{"name":"Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8931-8482","authenticated-orcid":false,"given":"Bente","family":"Glintborg","sequence":"additional","affiliation":[{"name":"Center for Rheumatology and Spine Diseases, Rigshospitalet, Glostrup, Denmark"},{"name":"Copenhagen Center for Arthritis Research and the DANBIO Registry, Rigshospitalet, Copenhagen, Denmark"},{"name":"Department of Clinical Medicine, University of Copenhagen, Copenhagen, 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