{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,2]],"date-time":"2026-04-02T00:56:24Z","timestamp":1775091384420,"version":"3.50.1"},"reference-count":28,"publisher":"BMJ","issue":"3","license":[{"start":{"date-parts":[[2024,9,30]],"date-time":"2024-09-30T00:00:00Z","timestamp":1727654400000},"content-version":"unspecified","delay-in-days":29,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"funder":[{"DOI":"10.13039\/100019016","name":"Assessment of SpondyloArthritis international Society","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100019016","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["RMD Open"],"accepted":{"date-parts":[[2024,9,9]]},"published-print":{"date-parts":[[2024,9]]},"abstract":"<jats:sec>\n                  <jats:title>Objectives<\/jats:title>\n                  <jats:p>To follow up four previously identified classes \u2018pure axial spondyloarthritis\u2019 (axSpA) (\u2018axial\u2019), \u2018axSpA with peripheral signs\u2019 (\u2018inflammatory back pain+peripheral\u2019), \u2018axSpA at risk\u2019 and \u2018no spondyloarthritis\u2019 (\u2018no SpA\u2019). They reflect the expert-opinion-free construct or \u2018Gestalt\u2019 of chronic back pain suspicious of axSpA. The aim was to assess participants\u2019 transitions between these classes over time.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Methods<\/jats:title>\n                  <jats:p>Participants with chronic back pain of \u22642 years duration, suspicious of axSpA from the SPondyloArthritis Caught Early cohort were analysed. Latent class (LCA) and latent transition analysis (LTA) using clinical, laboratory and imaging data at baseline and 2 years were calculated. Conditional and marginal probabilities were obtained, reflecting the probability of a spondyloarthritis feature in a class and the probability of the participant\u2019s class membership, respectively. Transitional probabilities were extracted revealing potential switches across classes. The analyses were performed in all participants using imputations for missing data and in participants with full data at baseline and 2 years.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Results<\/jats:title>\n                  <jats:p>Baseline and 2 years LCA models were constructed for 702 participants, resulting in the same four-class model as previously described. LTA revealed only a 3% transition from the \u2018no SpA\u2019 to the \u2018at-risk\u2019 class from baseline to 2 years with all other participants remaining in their initially assigned class. Sensitivity analysis on 384 participants with complete data at both baseline and 2 years showed similar results, underlining the model\u2019s robustness.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Conclusions<\/jats:title>\n                  <jats:p>Transitions between the four classes over 2 years were basically inexistent, highlighting the unlikelihood of developing new class-defining features of axSpA after an initial clinical workup.<\/jats:p>\n               <\/jats:sec>","DOI":"10.1136\/rmdopen-2024-004584","type":"journal-article","created":{"date-parts":[[2024,9,30]],"date-time":"2024-09-30T13:20:45Z","timestamp":1727702445000},"page":"e004584","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":3,"title":["Change in different classes of chronic back pain suspicious of axial spondyloarthritis: a latent transition analysis of the SPACE cohort"],"prefix":"10.1136","volume":"10","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6783-6422","authenticated-orcid":false,"given":"Philipp","family":"Bosch","sequence":"first","affiliation":[{"name":"Department of Rheumatology and Immunology, Medical University of Graz, Graz, Austria"},{"name":"Department of Rheumatology, Leiden University Medical Center (LUMC), Leiden, Netherlands"},{"name":"Department of Epidemiology, Maastricht University, Maastricht, Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1954-0229","authenticated-orcid":false,"given":"Alexandre","family":"Sepriano","sequence":"additional","affiliation":[{"name":"Department of Rheumatology, Leiden University Medical Center (LUMC), Leiden, Netherlands"},{"name":"Nova Medical School, Universidade Nova de Lisbona, Lisbon, Portugal"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3071-9425","authenticated-orcid":false,"given":"Mary-Lucy","family":"Marques","sequence":"additional","affiliation":[{"name":"Department of Rheumatology, Leiden University Medical Center (LUMC), Leiden, Netherlands"},{"name":"Centro Hospitalar e Universit\u00e1rio de Coimbra, Coimbra, Portugal"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5781-158X","authenticated-orcid":false,"given":"D\u00e9sir\u00e9e","family":"van der Heijde","sequence":"additional","affiliation":[{"name":"Department of Rheumatology, Leiden University Medical Center (LUMC), Leiden, Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0577-6620","authenticated-orcid":false,"given":"Robert","family":"Landew\u00e9","sequence":"additional","affiliation":[{"name":"Amsterdam Rheumatology Center, Amsterdam University Medical Center, Amsterdam, Netherlands"},{"name":"Department of Rheumatology, Zuyderland Medical Center, Heerlen, Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0601-4863","authenticated-orcid":false,"given":"Miranda","family":"van Lunteren","sequence":"additional","affiliation":[{"name":"Department of Rheumatology, Leiden University Medical Center (LUMC), Leiden, Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Liese","family":"de Bruin","sequence":"additional","affiliation":[{"name":"Department of Rheumatology, Leiden University Medical Center (LUMC), Leiden, Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0652-9808","authenticated-orcid":false,"given":"Manouk","family":"de Hooge","sequence":"additional","affiliation":[{"name":"Department of Rheumatology, Ghent University Hospital, Ghent, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Caroline","family":"Bastiaenen","sequence":"additional","affiliation":[{"name":"Department of Epidemiology, Maastricht University, Maastricht, Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sofia","family":"Exarchou","sequence":"additional","affiliation":[{"name":"Department of Clinical Sciences Malm\u00f6 (Rheumatology), Lund University, Malm\u00f6, Sweden"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9683-8873","authenticated-orcid":false,"given":"Roberta","family":"Ramonda","sequence":"additional","affiliation":[{"name":"Rheumatology Unit, Department of Medicine - DIMED, University Hospital of Padova, Padova, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0327-7860","authenticated-orcid":false,"given":"Karen 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