Validation of Sinhala version of Psoriasis Epidemiology Screening Tool

Psoriatic arthritis (PsA) occurs in one-third of patients with psoriasis and mostly remains undetected leading to debilitating deforming arthritis, eventually. The Psoriasis Epidemiology Screening Tool (PEST) is a quick and valid tool, widely used to detect PsA in clinical practice, and it has been validated to many languages. In this study, we intended to validate a Sinhala version of the PEST and assess its psychometric properties.

The Sinhala version of the questionnaire was tested on 199 patients with psoriasis attending the dermatology clinic at a tertiary care National Hospital in Sri Lanka. Patients who were detected to have PsA previously (n = 5) and those with other rheumatologic conditions (n = 12) were excluded. All patients were examined by a dermatologist, and demographic and disease characteristics were obtained. All patients were assessed by two rheumatologists who were blinded to the answers provided in the questionnaire. The diagnosis of PsA was made based on the CASPAR criteria.

We observed the total PEST score of 3 or more to be the best cutoff value to screen for PsA. This cutoff value showed the highest Youden index (sensitivity = 0.89, specificity = 0.95). In the ROC analysis, the area under the curve of the PEST_sv was 0.95 (SE 0.02, p < 0.001). PEST_sv total score showed a significant correlation with body surface area involved but not with Dermatology Life Quality Index or Psoriasis area and severity index score.

The Sinhala version of PEST demonstrated satisfactory performance as a screening tool for PsA. Key Points • Psoriatic arthritis (PsA) is the most debilitating complication of psoriasis and lack of quick, valid screening tool is a limiting factor for early identification in Sri Lankan context. • Sinhala version of the Psoriasis Epidemiology Screening Tool (PEST_sv) was tested on 199 patients with psoriasis and examined for the diagnosis of PsA according to Classification of Psoriatic Arthritis (CASPAR) criteria. • PEST_sv score of 3 or more was observed to be the best cutoff value to screen for PsA with sensitivity and specificity of 0.89 and 0.95 respectively. • PEST_sv demonstrated satisfactory performance as a screening tool for PsA.