Background/Purpose: Psoriatic arthritis (PsA) is a progressive, debilitating condition. It is estimated that between 25 and 35% of patients with psoriasis may develop psoriatic arthritis during the course of the disease. In these patients the psoriasis precedes the onset of PsA by an average of 10 years, so it is very important that dermatologists should be able to recognise the signs and symptoms of this in order to start the diagnostic process. The EARP (Early ARthritis for Psoriatic patients) questionnaire is a detection tool for PsA in psoriatic patients, which has good psychometric properties in its original Italian version that had not yet been validated for the Spanish population.

Methods: Observational, cross-sectional, multicentre study. A dermatologist and a rheumatologist participated at each centre. The dermatologist included patients between 18 and 85 years of age who had been diagnosed with psoriasis and who were not seeing a rheumatologist and did not have any other dermatological conditions. Basic sociodemographic and clinical variables were recorded. The patients answered the EARP questionnaire and a question about their health status. The rheumatologist then performed a physical examination of the same patients with additional analytical/radiological tests, if deemed necessary according to clinical practice, to conclude whether PsA was present/absent. The study was approved by the Independent Ethics Committee of Hospital de la Santa Creu i Sant Pau de Barcelona.

Results: 377 patients were included with a mean age (SD) of 48.1 (14.3) years, 56% male. 35.4% had completed secondary education and 42.5% were employed. A cut-off point of ≥4 points in the EARP questionnaire indicated a diagnosis of PsA. The EARP questionnaire was feasible (1.6% non-response) with good internal consistency (Cronbach’s α=0.776) and good construct validity, as there was a statistically significant correlation between the CASPAR criteria (p=0.01) and the rheumatologist’s diagnosis (p<0.01). The EARP questionnaire presented a sensitivity of 84.4% and a specificity of 62.9%, with a higher percentage of false positives than false negatives (37.1%;15.6%) (Table 2). No statistically significant sociodemographic differences were found between the patients who were and were not diagnosed with PsA by the rheumatologist.

Conclusion: The Spanish version of the EARP questionnaire is a valid tool for the early detection of PsA symptoms by dermatologists when assessing patients who are susceptible to this condition.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/validation-of-the-earp-questionnaire-detection-of-psoriatic-arthritis-in-the-spanish-population/