Incidence, baseline-associated factors and burden of difficult-to-manage axial spondyloarthritis: a 10-year analysis of the DESIR cohort.

OBJECTIVE: To determine the cumulative incidence of difficult-to-manage axial spondyloarthritis (D2M-axSpA) and treatment-refractory axSpA (TR-axSpA) in a recent-onset axSpA inception cohort, identify baseline factors and characterise long-term outcomes. METHODS: Patients from the French prospective DESIR (DEvenir des Spondyloarthrites Indifférenciées Récentes) cohort fulfilling the Assessment of Spondyloarthritis International Society (ASAS) 2009 criteria for axSpA and exposed to ≥1 biologic disease-modifying antirheumatic drug (bDMARD) were included. Patients with D2M-axSpA and TR-axSpA were classified according to both the ASAS definition and an extended definition adapted to historical treatment availability (failure of ≥3 b/targeted synthetic DMARDs regardless of mechanism of action). Cox proportional hazards models were used to identify baseline factors associated with D2M-axSpA. Clinical, imaging and socio-economic outcomes were analysed over up to 10 years of follow-up. RESULTS: Among 177 patients exposed to ≥1 bDMARD, the cumulative incidence of D2M-axSpA was 6.8% (95% CI 2.4 to 11.0) and 14.4% (95% CI 8.3 to 20.2) using the ASAS and extended definitions, respectively, while TR-axSpA remained rare (0.7% and 3.7%, respectively). Female sex and higher baseline disease activity were associated with the development of D2M-axSpA (extended definition). During follow-up, patients with D2M-axSpA according to the extended definition had a higher prevalence of fibromyalgia (60% vs 22.9%), greater healthcare resource utilisation (cumulative number of medical visits 110 vs 60) and opioid use (100% vs 72%). CONCLUSION: In this recent-onset axSpA inception cohort with long-term follow-up, D2M-axSpA was rare, rarely associated with true treatment refractoriness or structural progression and was accompanied by a persistent disease burden carrying a substantial socio-economic impact, highlighting the need for a broader, patient-centred approach to its management. TRIAL REGISTRATION NUMBER: NCT01648907.