Abstract / Summary
Abstract Background There is limited data on factors predicting the initiation of biologic and targeted synthetic disease modifying anti-rheumatic drugs (bDMARDs/tsDMARDs) in Spondyloarthritis (SpA) and Psoriatic arthritis (PsA). The relative importance of objective inflammation and other patient factors in this context is unclear. Methods A retrospective cohort study included consecutive patients diagnosed with SpA and PsA in 2012–2016 at a single rheumatology center. Data at diagnosis were obtained from medical records and from linkage to national and regional registers. Baseline predictors of b/tsDMARD initiation were assessed by Cox regression. Results Among 119 PsA patients (mean age 49 years, 49% male), 41.7% initiated b/tsDMARDs (median 15 months after diagnosis). In patients with PsA, older age was negatively associated with b/tsDMARD initiation (hazard ratio (HR) per standard deviation 0.74; 95% confidence interval (CI) 0.55–1.00), but no other significant predictors were identified. Among 120 SpA patients (mean age 38 years, 64% male), 41.5% initiated bDMARDs (median 7 months after diagnosis). Predictors included elevated CRP levels (HR 2.68; 95% CI 1.44–5.01) and bone marrow edema (BME) on magnetic resonance imaging of sacroiliac joints (SIJ) (HR 1.94; 95% CI 1.02–3.70). There was no significant association with age at SpA diagnosis, or with sex, education, family background, country of birth, or comorbidities. Conclusions Elevated CRP and SIJ BME at diagnosis were associated with bDMARD initiation in patients with SpA, while older patients with PsA may be less likely to start b/tsDMARDs. Education and ethnicity did not seem to influence b/tsDMARD initiation, suggesting equitable treatment access. Clinical trial number Not applicable.