Reliability and Validity of Persian Version of

Background and Quality of life is a very important concept in health care. This study was designed in order to translate and validate the Persian version of the Quality of Life Index (QLI) questionnaire. Permission was asked and a forward-backward translation procedure was followed to develop the Persian version of the questionnaire. Questionnaire was administered to 130 students in Social Welfare and Rehabilitation Sciences University. These students were selected on the basis of systematic random sampling. The QLI and SF-36 quality of life questionnaire and Vaux social support questionnaire were used in pretest. After two weeks interval only QLI questionnaire was used. Reliability of the questionnaire was estimated using internal consistency. Test re test reliability, concomitant validity and construct validity was assessed using coefficient of concordance and spearman's correlation. The internal consistency for the global score was 0.934 indicating that all domains met the minimum reliability standard, the Cranach's alpha ranged from 0.74 to 0.90 except for family subscale (α= 0.58). Test re test reliability showed good results for global score (spearman's correlation=0.89, ICC= 0.887) and for other domains except for family subscale (ICC= 0.255). The concomitant validity and construct validity revealed significant correlation between QLI with SF-36 questionnaire and Vaux questionnaire, respectively. Confirmatory factor analysis using EQS software also revealed that factor structure of the questionnaire in sample survey is repeated. The Persian version of the Quality of Life Index is a reliable and valid tool. However, further research is required to reduce the problems associated with reliability of family subscale.