Psoriatic arthritis flare incidence, definition and risk factors: a systematic review.

OBJECTIVES: We systematically reviewed the literature to identify the incidence of PsA flare, criteria used to define it and associated risk factors. METHODS: Databases of Embase, Medline ALL, Web of Science Core Collection and Cochrane Central Register of Controlled Trials were searched until September 2023, for original articles studying PsA flare. The Newcastle-Ottawa scale was used to assess the quality of included studies. RESULTS: Fifty-four studies of cohort, cross-sectional and clinical trial designs were included. Twelve studies assessed PsA flare rates, 28 assessed risk factors and 44 defined flare. The prevalence of current flare ranged between 7% and 50% (n = 8), while the incidence ranged between 10% and 27% over 6 months (n = 3), and 22% and 23% over 12 months (n = 2). Based on high-quality scoring, the current patient-reported flare was 10% (n = 1), while current physician-reported flare was 7% with 22-23% incidence rate over 12 months (n = 2). Criteria used in flare definition could be grouped into seven categories, with disease activity scores (36%), patient-reported (39%) and physician-reported (30%) flare and change in therapy (25%) being frequently used. Risk factors could be grouped into four categories: arthritis therapies, SARS-CoV, PsA features and other. The factors showed limited or unclear evidence. CONCLUSION: The current prevalence of flare ranged between 7% and 10%, and the annual incidence was 22-23%, based on high-quality scoring. Forty-four studies defined flare, revealing no consensus on a single flare definition, and highlighting the need for a standardized definition. No conclusions could be drawn on risk factors, highlighting the need for further research. PROSPERO REGISTRATION: CRD42024482657.