The Norwegian version of the dermatology life quality index: a study of validity and reliability in psoriatics

The aim of this study was to test the Norwegian version of the Dermatology Life Quality Index (DLQI-N) for validity and reliability in psoriatic patients. The DLQI-N was administered to 230 patients with psoriasis who underwent climate therapy on Gran Canaria, with a dermatologist assessing their psoriasis severity using the Psoriasis Area and Severity Index. Factor analyses resulted in a unidimensional pattern, which supports the use of a total DLQI-N score. The internal consistency coefficient of this unidimensional measure was 0.90 (Cronbach's alpha) and the paired inter-item correlations ranged from 0.20 to 0.76 (p<0.01). Questions related to work, sport and sex were the issues most often ticked off as not relevant, and the item related to working/studying was often misunderstood. DLQI-N scores were significantly associated with disease severity, age and sex. We assess DLQI-N as a valid, reliable and clinically useful outcome measure for quality of life in Norwegian patients with psoriasis.