Further evidence of the validity and reliability of the Skindex-29: an Italian study on 2,242 dermatological outpatients

BACKGROUND: Quality of life is increasingly recognized as an important measure in dermatology. The Skindex-29 is a self-administered questionnaire recently developed to measure comprehensively the complex effects of skin diseases on patients' quality of life. OBJECTIVE: We aimed to provide further evidence of the reliability and validity of the Skindex-29 in a large sample of patients affected by a wide variety of skin diseases. METHODS: An Italian version of the Skindex-29 was produced following accepted guidelines for the cross-cultural adaptation of questionnaires. All adult outpatients attending a dermatological hospital on predetermined days were given the Skindex-29 and the 12-item General Health Questionnaire (GHQ-12). RESULTS: A total of 2,242 complete questionnaires were analyzed. The internal consistency and test-retest reliability of each scale were high. The factor structure of the Skindex-29 was strikingly similar to the one originally observed in American patients. The pattern of correlation with the GHQ-12 provided evidence of convergent validity of the Skindex-29. CONCLUSION: The instrument seems to measure three fundamental dimensions of skin health-related quality of life.