Objective: Dermatologists usually see patients with psoriasis before arthritis develops, making them well placed to diagnose early PsA (ePsA). This study aimed to develop a rapid and robust screening questionnaire for predicting PsA in patients with psoriasis referred to a specialized joint dermatology-rheumatology combined clinic.
Methods: In all, 228 psoriasis patients naïve to DMARD treatment were administered two screening questionnaire: the new Early ARthritis for Psoriatic patients (EARP) questionnaire and the existing Psoriatic Arthritis Screening and Evaluation (PASE) questionnaire. The diagnostic accuracy of the two questionnaires for the diagnosis of ePsA was compared by receiving operating characteristics curves.
Results: After psychometric analysis, a simplified questionnaire of 10 items was found to have good internal reliability (Cronbach's α = 0.83) and was much faster and simpler to administer than the PASE. Both the EARP and PASE questionnaires presented similar receiving operating characteristics curves (specificity 91.6 and 67.2 and sensitivity 85.2 and 90.7, respectively) in identifying ePsA patients by using the cut-off value of 3 for EARP-10 and the standard cut-off value of 44 for PASE. The CASPAR criteria for PsA were present in 61 (26.7%) of the patients at clinical presentation and in 32.9% at 1-year follow-up, and the EARP score of ≥3 correlated with clinically determined arthropathy by a rheumatologist.
Conclusion: The EARP questionnaire is simple and fast to administer and proved robust for the identification of PsA in the dermatological setting. Dermatologists should consider the EARP for patients attending clinics, as it correlates well with early PsA diagnosis.