Validity and reliability of the Persian version of the Dutch musculoskeletal questionnaire

Background: Dutch Musculoskeletal Questionnaire (DMQ) is used to examine physical and environmental risk factors and to identify high-risk groups for exposure to the risk factors of musculoskeletal disorders at workplace. The aim of this study was to develop the Persian version of the DMQ and to assess its psychometric properties. Methods: This study was conducted on 212 employees of Gas Transmission Company. Using a standard forward-backward translation procedure, the English version of the questionnaire was translated into Persian and culturally adapted. Content validity was established by 10 expert opinions. The intraclass correlation coefficient (ICC) was used for the statistical analysis of reproducibility. Kuder-Richardson-20 was used for internal consistency and confirmatory factor analysis for structural validity. Results: This study revealed high internal consistency and good test-retest reliability for the Persian version of the questionnaire. The means of the content validity ratio (CVR) and content validity index (CVI) for the total 35 items of the questionnaire were 0.96 and 0.91, respectively. The internal consistency of the factors was satisfactory, ranging from 0.83 to 0.88. Confirmatory factor analysis confirmed the existence of 7 factors in the questionnaire and an acceptable fit for the Persian version of the DMQ. Conclusion: The Persian version of the DMQ has acceptable psychometric properties. Thus, it can be used as a valid instrument to assess workload and to identify high-risk groups of musculoskeletal disorders at workplace.