A validation study of the Simple Psoriatic Arthritis Screening (SiPAS) questionnaire to screen psoriasis patients for psoriatic arthritis

Objective To validate in a multicentric cohort of patients a self-administered PsA screening tool, called Simple Psoriatic Arthritis Screening (SiPAS) questionnaire, to screen psoriasis patients for signs and symptoms of PsA. Methods The SiPAS questionnaire was validated in a multicentric Italian cohort of psoriasis patients referred to two rheumatological centres. Results A total of 202 psoriasis patients were screened with SiPAS in the validation study. Sixty-two psoriasis patients (30.7%) were diagnosed with PsA. The five screening questions (1. Have you ever had a finger or a toe and/or another joint swollen and painful without any apparent reason?; 2. Occasionally, has an entire finger or toe become swollen, making it look like a 'sausage'?; 3. Do you wake up at night because of low back pain?; 4. Have you had pain in your heels?; 5. Has a doctor ever diagnosed you with psoriatic arthritis?) with a dichotomous response, demonstrated high sensitivity and specificity for predicting PsA. Likelihood ratios for individual parameters varied between 2.06 and 4.75. Using the Bayesian Analysis, the presence of three of five items answered as "yes" showed respectively a sensibility and a specificity of 79% and 87%, with a positive likelihood ratio of 6.14. Conclusion The SiPAS questionnaire is able to quickly screen psoriasis patients for PsA. A SiPAS score ≥3 is an indication for referral to a rheumatologist. The SiPAS needs further validation.