Psychometric Properties of the Persian Version of the World Health Organization's Quality of Life Questionnaire (WHOQOL-100)

Background: In recent decades there has been increasing focus on developing and localizing quality of life (QOL) instruments in different societies. In this study, we aim to translate WHO's Quality of Life WHOQOL-100 questionnaire into the Persian language and assess the validity and reliability of the translated version.

Methods:   We used a forward-backward procedure to translate the questionnaire. A pilot sample of 60 university students was recruited to assess the repeatability and construct validity of the instrument. To assess the construct validity, 60 university students filled out both the WHOQOL-100 and WHOQOL-BREF questionnaires. Then, 500 healthy and 500 disabled individuals were randomly selected using a multi-stage sampling technique. The internal consistency of the Persian version of the WHOQOL-100 was evaluated using Cronbach's alpha in the sample. In addition, a multiple linear regression model was utilized for assessing the discriminant validity of this instrument, adjusting for different confounders.

Results: Test-retest analysis of data from the pilot sample showed that the Persian version of the WHOQOL-100 has acceptable repeatability (ICCs for all six domains were higher than 0.7). In addition, computation of the correlation between the domains of WHOQOL-100 and WHOQOL-BREF showed satisfactory construct validity. Analyzing the data from 500 healthy and 500 disabled persons revealed that all domains of WHOQOL-100 met the minimum level of acceptable internal consistency. Multiple regression results showed acceptable discriminant validity for all domains of the Persian version, except for the spiritual domain.

Conclusion: In general, the Persian version of the WHOQOL-100 had satisfactory reliability and validity for assessing QOL of Iranian people. However, we recommend further research for challenging the problem of the spiritual domain.