Comparative performance of psoriatic arthritis screening tools in patients with psoriasis in European/North American dermatology clinics

Abstract

General practitioners/dermatologists may be aware of musculoskeletal symptoms in patients with psoriasis but may have difficulty accurately detecting psoriatic arthritis (PsA). We sought to evaluate 3 PsA screening questionnaires-the Psoriasis and Arthritis Screening Questionnaire (PASQ), Psoriasis Epidemiology Screening Tool (PEST), and Toronto Psoriatic Arthritis Screen (ToPAS)-based on rheumatologist assessment in patients with psoriasis. Consecutive unselected patients with psoriasis, initially evaluated by dermatologists for plaque psoriasis, were randomized to receive 1 of 3 questionnaires. Patients were subsequently evaluated by rheumatologists to establish/exclude clinical PsA diagnosis. Using clinical PsA diagnosis as the standard for comparison, questionnaire accuracy was assessed by calculating sensitivity/specificity and positive/negative predictive values. Of 949 patients with psoriasis evaluated by rheumatologists, 285 (30%) received a clinical diagnosis of PsA (95% confidence interval 27%-33%). Probable PsA was detected in 45.1%, 43.0%, and 42.9% of patients using PASQ, PEST, and ToPAS, respectively. Sensitivity ranged from 0.67 to 0.84; specificity, 0.64 to 0.75; positive predictive value, 0.43 to 0.60; and negative predictive value, 0.83 to 0.91. Not all patients completed all questionnaires; lack of standardized diagnostic criteria introduced possible bias. PASQ, PEST, and ToPAS are useful screening tools that can help dermatologists identifypatients without PsA and patients with possible PsA who may benefit from rheumatologist assessment.