Validation of Turkish psoriatic arthritis screening tool for psoriatic arthritis: A cross-sectional comparative study

Psoriasis (PsO) is a chronic immune-mediated disease that affects the skin and nails. Several screening tools such as psoriasis epidemiology screening tool, psoriatic arthritis screening and evaluation, early arthritis for psoriatic patients (EARP), STRIPP, SIPAS, and TOPAS have been developed and validated for identifying patients with suspected psoriatic arthritis (PsA) in dermatology clinics. Herein, we aim to validate and evaluate the performance of TurPAS in patients with PsO compared to the EARP questionnaire. This cross-sectional study was carried out in collaboration between dermatology and rheumatology clinics at Aksaray University Hospital, a tertiary referral center. All patients were examined for dermatologic aspects in the dermatology outpatient clinic and TurPAS and EARP questionnaires were performed by the same dermatologist. The patients who met the CASPAR criteria were classified as PsA in addition to appropriate clinical findings. In our study, 119 patients (n = 72; 60.5% female) with PsO were included. Mean ± standard deviation age of the patients was 44.9 ± 14.3 (range; 18-83) years and the median (IQR) PsO duration was 10 (14) years. Median (IQR) TurPAS and EARP scores were 2 (3) and 3 (5), respectively. Overall, 39 patients (32.8%) met the CASPAR criteria and were classified as PsA. The best diagnostic accuracy was observed in ≥ 3 positive items with 82% and 70% sensitivity and specificity (positive predictive value: 57.1%, negative predictive value: 89%, likelihood ratio: 2.7, diagnostic accuracy: 74%) for TurPAS and ≥ 4 items with 74.4% and 86.3% (positive predictive value: 72.5%, negative predictive value: 87.3%, likelihood ratio: 5.4, diagnostic accuracy: 82.4%) for EARP. In our study, approximately one-third of patients with PsO were diagnosed as PsA. TurPAS had acceptable diagnostic performance compared to the EARP questionnaire.