Definition and construct validation of clinically relevant cutoffs on the Flare Assessment in Rheumatoid Arthritis (FLARE-RA) questionnaire

Objective: The Flare Assessment in Rheumatoid Arthritis (FLARE-RA) questionnaire was devised for the detection of flares in patients with RA. We aimed to define construct validity and cut-off(s) for the FLARE-RA questionnaire. Methods: This cross-sectional study included adult patients with prevalent RA (2010 ACR/EULAR criteria) attending outpatient rheumatology clinics in France (n = 138), Denmark (n = 253), USA (n = 75), and Argentina (n = 105). Flare occurrence over the past 3 months was assessed with the FLARE-RA questionnaire scoring from 0 (no flare) to 10 (maximum flare). The cut-offs for the FLARE-RA score were defined using the following anchor items obtained at the same encounter: (1) Patient report of flare; (2) DAS28-CRP > 3.2; (3) Change of anti-rheumatic treatment, based on the area under the receiver operating characteristic curve (AUC) and distance to (0,1). Results: Four hundred seventy four patients with RA duration ≥2 years (mean age 58.6 years, 74.9% female) were included in the main analysis. The discrimination for the FLARE-RA cut-offs was acceptable-to-excellent: AUC for the global FLARE-RA score ranged from 0.71 to 0.92. The cut-offs for the FLARE-RA score were lower using “patient report of flare” than DAS28-CRP and “change of anti-rheumatic treatment”. Proposed FLARE-RA cut-offs for clinical detection and change of anti-rheumatic treatment are 2 and 5, respectively, for patients with RA duration 2–5 years, and 2 and 3.5, respectively, for patients with RA duration >5 years. Conclusions: Proposed FLARE-RA cut-offs have acceptable discriminative capacity across the tested anchor items and are expected to aid in early recognition and timely management of RA flares.