Development of skin disease disability index to assess the dermatologic burden in Nepal

Introduction: Skin disease is one of the leading cause of morbidity worldwide. Most instruments measuring the impact of skin disease on quality of life are developed in the west and not applicable to the socio-cultural situation in Nepal. The aim of the study was to develop and validate a questionnaire to measure quality of life impairment due to skin disease in Nepal. Methods: Different aspects of quality of life impairment were identiÞ ed from 35 in-depth interviews and two focus group discussions, with villagers with various skin diseases. Based on this information, 10 questions scoring the influence of skin diseases on quality of life – Skin Disease Disability Index (SDDI) – was developed. This instrument was tested and validated in 212 villagers with skin disease and in 100 healthy villagers. Results: The maximum total Skin Disease Disability Index score was 36. There was a wide variation in total Skin Disease Disability Index score between individuals with skin disease (range 1-33) with a mean score of 13.2, while in controls the mean total score was 1 (p<0.001). Thus, the Skin Disease Disability Index clearly discriminates between these two groups. The difference in mean score for single questions between patients and controls was also highly significant (p<0.001). Conclusions: The questionnaire clearly covered all aspects of quality of life related to skin disease and was, simple, robust, easy to use and well accepted by the selected population. The Skin Disease Disability Index was reliable in the overall score as well as in individual questions.