Development and psychometric validation of a patient-reported outcome measure to assess fears in rheumatoid arthritis and axial spondyloarthritis: the Fear Assessment in Inflammatory Rheumatic diseases (FAIR) questionnaire.

Objectives: To develop and validate an outcome measure for assessing fears in patients with rheumatoid arthritis (RA) and axial spondyloarthritis (axSpA).

Methods: Fears were identified in a qualitative study, and reformulated as assertions with which participants could rate their agreement (on a 0-10 numeric rating scale). A cross-sectional validation study was performed including patients diagnosed with RA or axSpA. Redundant items (correlation >0.65) were excluded. Internal consistency (Cronbach's α) and factorial structure (principal component analysis) were assessed. Patients were classified into fear levels (cluster analysis). Associations between patient variables and fear levels were evaluated using multiple logistic regression.

Results: 672 patients were included in the validation study (432 RA, 240 axSpA); most had moderate disease activity and were prescribed biologics. The final questionnaire included 10 questions with high internal consistency (α: 0.89) and a single dimension. Mean scores (±SD) were 51.2 (±25.4) in RA and 60.5 (±22.9) in axSpA. Groups of patients with high (17.2%), moderate (41.1%) and low (41.7%) fear scores were identified. High fear scores were associated with high Arthritis Helplessness Index scores (OR 6.85, 95% CI (3.95 to 11.87)); high Hospital Anxiety and Depression Scale anxiety (OR 5.80, 95% CI (1.19 to 4.22)) and depression (OR 2.37, 95% CI (1.29 to 4.37)) scores; low education level (OR 3.48, 95% CI (1.37 to 8.83)); and high perceived disease activity (OR 2.36, 95% CI (1.10 to 5.04)).

Conclusions: Overall, 17.2% of patients had high fear scores, although disease was often well controlled. High fear scores were associated with psychological distress. This questionnaire could be useful both in routine practice and clinical trials.