Translation, cultural adaptation, and validation of the American Skindex-29 quality of life index

BACKGROUND: Measuring the quality of life measure of patients with dermatologic diseases is an important concern. The instruments to evaluate it are commonly originally written in English and need to be translated and validated to be used in different cultures. OBJECTIVE: The purpose of this paper is to translate and validate the Skindex-29 questionnaire to Brazilian Portuguese to be used in our country as a quality of life assessment instrument in dermatologic patients. METHODS: The first step was the translation from English to Brazilian Portuguese and the back-translation by two native speakers. The translated version was then used for the second step, when three questionnaires were applied to 75 patients (43 of whom were classified as lightly affected and 32 as heavily affected by their dermatologic conditions): an identification questionnaire, the translated version of Skindex-29, and the Brazilian Portuguese version of Dermatologic Life Quality Index (DLQI). Additionally, the generic questionnaire Short Form 36 (SF-36) was applied to 41 of these patients. The last step to evaluate reproducibility was repeating the Skindex-29 questionnaire by the same researcher one week later in 44 patients. RESULTS: Reliability was observed in global Skindex-29 scale (α=0.934), and its domains emotions (α=0.926), symptoms (α=0,702), and psycosocial functioning (α=0.860). The reproducibility showed high intraclass correlations. High intra class correlations was observed, thus validating reliability. CONCLUSIONS: The Skindex-29 quality of life questionnaire was properly translated and validated to Brazilian Portuguese