Evaluation and validation of a patient completed psoriatic arthritis flare questionnaire

Objective Evaluation of a psoriatic arthritis (PsA), multidimensional, patient completed disease flare questionnaire (FLARE).

Methods The FLARE questionnaire was administered to 139 patients in a prospective observational study. The ‘gold standard’ of flare was based on patient opinion. Test-retest was evaluated by intra-class correlation coefficient (ICC). Disease activity was measured by the PASDAS, GRACE, CPDAI and DAPSA.

Results The most common symptoms of a PsA flare were musculoskeletal, followed by fatigue, frustration, loss of function and an increase in cutaneous symptoms. The test-retest ICC for the FLARE questionnaire was 0.87 (95% CI 0.72 – 0.94). The optimum cut-off to identify a flare of disease was 4/10 (sensitivity 0.82, specificity 0.76; area under curve 0.85). For those patients scoring 4 or above, the mean score for the composite measures was as follows (score for those not reporting a flare in brackets): PASDAS, 5.3 ± 1.3 (3.1 ± 1.6); GRACE, 4.5 ± 1.2 (2.2 ± 1.4); CPDAI, 8.9 ± 2.5 (4.7 ± 3.1); DAPSA, 38.2 ± 20.3 (16.8 ± 14.9). In a new flare the increase in composite measure score was calculated as follows; 1 for PASDAS and GRACE, 2 for CPDAI, 7 for DAPSA. Moderate agreement was found between the definition of flare using the cut-off of 4, indicated by subjects in a separate question.

Conclusion A PsA flare displays escalation of symptoms and signs across multiple domains; the FLARE questionnaire has external validity both in terms of composite disease activity and overall patient opinion of the state of their condition.