Identifying flare prone Spondyloarthritis – insights from a prospective cohort

Objectives: To determine characteristics of flares in spondyloarthritis and to identify differences between flare and non-flare populations. Methods: A cohort of 106 patients (2650 patient-weeks follow-up and 318 visits) who fulfilled the ESSG or ASAS classification criteria for SpA were followed up for 6 months. The diagnosis of flare was made by rheumatologist using patient-reported indices and ruling out confounders. Results: 67/ 106 (63.2%) patients were diagnosed flare at 6 months of which 51 (76.1%) developed major/ generalized flares and 16 (23.9%) developed minor/ localized flares. Shorter time since diagnosis (disease duration less than 6 years), current/ past history of enthesitis at baseline, steroid requirement and high disease activity at baseline were significantly favouring flares and ax-SpA was associated with lower tendency to flare in univariable analyses. Multivariable logistic regression analyses revealed inactive (OR 0.21 [95% CI 0.047–0.942], p = 0.042) or low disease at baseline (OR 0.25 [95% CI 0.089–0.718], p = 0.011) was significantly associated with lower tendency of flare while current/ past enthesitis (OR 11.29 [95% CI 1.3–93.46], p = 0.025) favoured greater tendency to flare, with variable effect size. A general linear model for repeated measures revealed significant differences in longitudinal change in all ASAS validated indices between flare and non-flare groups. Conclusion: The study identifies predictors in spondyloarthritis with increased tendency to flare. The results suggest that patients with low/ inactive disease at baseline may have fewer flares and enthesitis may associate with higher tendency to flare.