Translation and validation of the Serbian version of the Skindex-29 instrument for measuring impact of skin disease on quality of life

The Skindex-29 instrument, which is intended for measuring the influence of skin diseases on quality of life, was developed and validated in several languages. However, a Serbian translation of the instrument is not available. The aim of this study was to translate the Skindex-29 from English to Serbian, to make necessary cultural adaptations, and to test its psychometric properties in a sample of outpatients with various skin diseases. The Skindex-29 was translated and adapted according to internationally accepted guidelines and then tested on a sample of Serbian outpatients with various skin diseases. Internal consistency was checked through calculation of Cronbach’s alpha and Interclass Correlation Coefficient for the instrument’s domains. The criterion validity of the translation was tested by correlating scores of domains with scores on the Serbian version of Dermatological Life Quality Index (DLQI).Validity of the construct was tested through comparison of the domains scores in groups of patients with different skin diseases. Fifty-three patients (18.6%) suffered from acne vulgaris, 48 (16.8%) from verrucae vulgares, 40 (14.0%) from psoriasis, 34 (11.9%) from an undetermined type of mild dermatitis, 20 (7.0%) from venous ulcers, 19 (6.7%) from eczema, and 71 (24.9%) from other skin diseases. The Serbian translation of Skindex-29 showed good internal consistency: Cronbach’s alpha for Emotional, Symptoms, and Functioning domains was 0.885, 0.752, and 0.901, respectively. Validity of the instrument in all aspects (criterion, content, and construct validity) was satisfactory, yet the Symptoms domain could not discriminate well between more and less severe skin diseases. The Serbian translation of Skindex-29 appears to be a reliable and valid specific instrument for measuring the adverse influence of skin diseases on quality of life.