Psoriatic Arthritis Flares Show Variable Incidence, Lack of Consensus on Definition

The incidence and definition of psoriatic arthritis (PsA) flares remain inconsistently characterized across the literature, according to a systematic review published in Rheumatology.

The authors reviewed 54 studies spanning cohort, cross-sectional, and clinical trial designs to clarify flare rates, criteria used for identification, and potential risk factors.

Twelve studies assessed flare incidence, with results demonstrating substantial variability. The prevalence of current flare ranged from 7% to 50%, while incidence estimates ranged between 10% and 27% over 6 months and 22% to 23% over 12 months. Higher quality studies suggested lower rates: one patient-reported study identified a 10% prevalence, whereas physician-reported flares were 7% with a 22% to 23% annual incidence.

The review identified 44 unique flare definitions, grouped into 7 categories. Among these, disease activity scores (36%), patient-reported outcomes (39%), physician assessments (30%), and change in therapy (25%) were the most frequently used. This heterogeneity highlighted the absence of a standardized framework. “No consensus definition of PsA flare exists, which complicates both research interpretation and clinical application,” the authors noted.

Risk factors for flare were investigated in 28 studies and broadly categorized into therapy-related, PsA-specific features, SARS-CoV exposure, and other miscellaneous variables. However, the evidence was either limited or inconclusive, precluding definitive conclusions.

The findings suggest that, based on the most rigorous studies, the current prevalence of flare is 7% to 10%, with an annual incidence of approximately 22% to 23%. Despite the frequency of flare events, the lack of an agreed-upon definition poses challenges for trial comparability, patient care, and the development of targeted interventions.

The authors emphasize the need for further research to establish standardized diagnostic criteria. “The absence of a uniform definition of flare and the inconclusive evidence on risk factors highlight an important gap in PsA research,” they concluded.

Reference:

Hojeij B, Koc GH, Luime JJ, Vis M, Coates LC, Kok MR, Tchetverikov I. Psoriatic arthritis flare incidence, definition and risk factors: a systematic review. Rheumatology. 2025;64(9):4886-4901. doi:10.1093/rheumatology/keaf247