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

Background: General practitioners/dermatologists may be aware of musculoskeletal symptoms in patients with psoriasis but may have difficulty accurately detecting psoriatic arthritis (PsA).

Objective: 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.

Methods: 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.

Results: 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.

Limitations: Not all patients completed all questionnaires; lack of standardized diagnostic criteria introduced possible bias.

Conclusion: PASQ, PEST, and ToPAS are useful screening tools that can help dermatologists identify patients without PsA and patients with possible PsA who may benefit from rheumatologist assessment.