Cross-cultural validation and psychometric properties of the Brazilian Portuguese version of the Psoriasis Epidemiology Screening Tool (PEST-bp)

Although the Psoriasis Epidemiology Screening Tool (PEST) questionnaire is a useful tool for screening patients for psoriatic arthritis (PsA), it has not been validated in Portuguese. Our aim was to perform a cross-cultural validation of the PEST for Brazilian Portuguese, as well as to analyse its psychometric properties and to test the association of PEST scores with patient clinical characteristics. The first step was the translation and cross-cultural adaptation of the PEST questionnaire into Brazilian Portuguese, which included forward translation, synthesis, back translation, consolidation with an expert panel and cognitive debriefing with pilot testing. The second step was validation and psychometric testing, in which 124 dermatology patients with no previous PsA diagnosis completed the new adapted questionnaire (PEST-bp). Patients were initially assessed by a dermatologist for clinical characteristics, then they answered the Dermatology Life Quality Index (DLQI) and PEST-bp questionnaires. Afterwards, a rheumatologist, blind to former tests, evaluated the presence of PsA according to CASPAR criteria. The PEST-bp proved to be 0.81 accurate (95% CI: 0.73-0.88) in the ROC curve, indicating a cutoff score >= 3 as suggestive of PsA (sensitivity = 84.6%, specificity = 63.3%). The assessment of internal consistency, via the Cronbach test, presented a coefficient of 0.72 (acceptable). A higher PEST-bp score was positively associated with lower quality of life scores and with male patients. In conclusion, the PEST-bp questionnaire proved to be suitable as a screening tool for PsA in patients with psoriasis. Elevated PEST-bp scores are associated with decreased patient quality of life.