Reliability and validity of the Arabic version of the Psoriasis Disability Index questionnaire

Background Psoriasis has a significant negative impact on patients’ quality of life. Psoriasis Disability Index (PDI) is a psoriasis-specific questionnaire that was developed by Finlay and Coles, which concerns the functional lifestyle disabilities caused by psoriasis. It has been used internationally for almost 20 years and has been translated into at least 26 languages. Objective The objective of this study was to evaluate the reliability and validity of the Arabic version of the PDI questionnaire for Egyptian psoriasis patients. Patients and methods One hundred adult Egyptian patients with chronic plaque-type psoriasis aged 16 years or older with no other systemic disease were enrolled in this study. The patients were examined to determine the clinical type of psoriasis and to measure the severity of psoriasis by calculating Psoriasis Area Severity Index score. The impact of psoriasis on quality of life was assessed using the Arabic version of the PDI after translation and cultural adaptation according to WHO guidelines. Results The internal consistency for the 15 items of the Arabic version of the PDI questionnaire was significant; intraclass correlation coefficient was 0.853 and Cronbach’s α coefficient was 0.860, indicating reliability of the developed Arabic version. Conclusion The Arabic version of the PDI questionnaire was found to be a reliable and valid measure for evaluating the quality of life for Egyptian patients with psoriasis.