Validation and Field Performance of the Italian Version of the Psoriatic Arthritis Screening and Evaluation (PASE) Questionnaire.

Psoriatic arthritis (PsA) is a potentially severe inflammatory condition (entheso-arthro-osteopathy), and early diagnosis is important to guide treatment choices in patients with psoriasis. The objective of this study is to further validate the PsA Screening and Evaluation (PASE) questionnaire, and to assess its field performance. Data were collected in 10 Italian centres, and the PASE was administered at baseline, after 3 days and after 3 months. The Skindex-29 was also administered. To determine the best cut-off value to identify patients with PsA we produced receiver operating characteristic (ROC) curves using the rheumatologist's diagnosis as outcome. Of the 298 patients that were enrolled, 28% were classified as having PsA according to the CASPAR criteria, while 19% had received a diagnosis of PsA from a rheumatologist. PASE score were always significantly different in patients with or without PsA, while Skindex-29 scores never were. The internal consistency of the PASE was very good (Cronbach's α of 0.90-0.95), the test-retest reliability was also very high (intraclass correlation coefficients 0.91-0.93), and the PASE scores showed good responsiveness to clinical change over time. The optimal cut-off identified through the ROC curves was ≥ 48 on the total PASE score, which was able to distinguish PsA from non-PsA patients with a 73.2% sensitivity and a 76.1% specificity. Our results confirm the good psychometric properties of the PASE, and indicate that it may be a useful tool for the dermatologists, both to screen for PsA and to obtain a standardized patient-reported measure to monitor and evaluate the health status of the patients with PsA.