The Spanish version of Skindex-29. An instrument for measuring quality of life in patients with cutaneous diseases

Quality-of-life studies aim to measure objectively how patient life is affected by disease. Generation of a novel instrument is more expensive and time-consuming than adapting a test already existing in another language. Skindex-29 is a widely validated American instrument to measure quality of life in patients with cutaneous disease. A study of the psychometric properties of the Spanish version of Skindex-29 is presented. The test was administered to adults in an outpatient dermatological clinic. Age, sex and disease were registered for each patient. Three groups were studied: healthy people, patients with inflammatory skin disease and patients with isolated or tumoral lesions. Construct validity, internal consistency, reproducibility at 72 hours, responsiveness and feasibility were evaluated. Responses of 318 patients were analyzed; 65% were women, with a mean age of 36 years. Validity construction was demonstrated, with significant differences between healthy people and patients as well as between both groups of patients. Reliability was also demonstrated, with Cronbach's coefficient alpha values above 0.84 and intraclass correlation values above 0.7. The test showed responsiveness to clinical change. The percentage of non-response was low, and floor and ceiling effects were adequate. The Spanish version of Skindex-29 constitutes an instrument with validity, reliability, and sensitivity to change to measure the effects of cutaneous conditions on quality of life of Spanish patients.