Validation study of Sinhala version of the dermatology life quality index (DLQI).

INTRODUCTION The effect of dermatological disease on patients' quality of life is a minimally addressed issue in Sri Lanka. One reason is the unavailability of a standardised measuring tool. This study was done to produce and validate a Sinhala version of the Dermatology Life Quality Index (DLQI), which is an internationally accepted quality of life measuring instrument. METHODS The English version of the DLQI was translated according to standard procedures and the translated version was validated among 200 outpatients attending the dermatology clinics at the National Hospital of Sri Lanka and 30 healthy volunteers. The SF-36 was administered simultaneously to a random subsample of 125 participants to test for criterion validity. Intemal consistency and the test-retest reliability were assessed separately for the translated DLQI. RESULTS The Sinhala version of DLQI takes 3-5 minutes to be completed on average and had no confusing, embarrassing or difficult to answer questions. Except for personal relationship domain (0.442) all other domains demonstrated high Cronbach's alpha values suggesting satisfactory internal consistency within the domains. The DLQI demonstrated good test-retest reliability with all Kappa values above 0.83. In comparison with the relevant domains of the SF-36, the DLQI demonstrated greater than 0.4 (Pearson r) suggesting an acceptable criterion validity. The Sinhala version of the DLQI appears to discriminate well between disease status and disease severity (F = 31.09, p < 0.001, n = 240). CONCLUSIONS The DLQI (Sinhala) version is a simple, acceptable and reliable tool to measure the effect of dermatological diseases on quality of life.