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

Abstract Objectives We systematically reviewed the literature to identify the incidence of psoriatic arthritis (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%-50% (n = 8), while the incidence ranged between 10%-27% over 6 months (n = 3), and 22%-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%-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