Performance of screening tools for psoriatic arthritis: a cross-sectional study in primary care

Objective. To compare the screening performance of the Psoriasis Epidemiology Screening Tool (PEST), Psoriatic Arthritis Screening and Evaluation (PASE) and Early Arthritis for Psoriatic Patients (EARP) questionnaires for detecting PsA among psoriasis patients in a primary care setting. Methods. In a cross-sectional study, 473 primary care psoriasis patients at risk for PsA completed the PEST, PASE and EARP questionnaires and were clinically evaluated by a trained research nurse. A PsA case was defined by a rheumatologist according to the CASPAR criteria. Sensitivity and specificity were determined for the PEST and EARP cut-offs (a (c) 3/43) and the PASE cut-offs (a (c) 3/4 44 and a (c) 3/4 47). Results. PsA was diagnosed in 53 patients. The PEST had a sensitivity of 0.68 and a specificity of 0.71. The PASE was validated for two different cut-offs. The cut-off of 47 led to a sensitivity of 0.59 and a specificity of 0.66, whereas the lower cut-off of 44 led to a sensitivity of 0.66 and a specificity of 0.57. For the EARP we found a sensitivity of 0.87 with a specificity of 0.34. Conclusion. The PEST questionnaire has the most favourable trade-off between sensitivity and specificity to screen for PsA. However, as the prevalence of psoriasis and PsA is fairly low in primary care, screening only psoriasis patients with musculoskeletal complaints may be a better allocation of resources.