RESUMO
STUDY DESIGN: Descriptive cross-sectional study. PURPOSE: To validate the Persian version of the Million Visual Analogue Scale Questionnaire (MVAS), a self-administered low back pain (LBP) questionnaire. OVERVIEW OF LITERATURE: The majority of LBP questionnaires translated into Persian evaluate the impact of LBP on daily living. The MVAS is one of the most commonly used self-administered LBP questionnaires, and was developed to assess a different direction and effect of activities of daily living on LBP intensity. METHODS: The questionnaire was translated into Persian with the forward-backward method and was administered to 150 patients randomly sampled from an occupational medicine clinic in Tehran in 2017. RESULTS: Cronbach's alpha for all subscales ranged between 0.670 and 0.799. Confirmatory factor analysis showed adequate construct validity of the Persian version of the MVAS, with root mean square error of approximation 0.046, goodness of fit index 0.902, and comparative fit index 0.969. Other indexes were satisfactory. CONCLUSIONS: The Persian MVAS is a valid and reliable instrument that can assess the effect of various daily activities on the intensity of LBP.