Validation of the simplified Chinese version of the quality of life questionnaire of the European foundation for osteoporosis (QUALEFFO-31)

To translate quality of life questionnaire of the European foundation for osteoporosis (QUALEFFO-31) into a simplified Chinese version, and test its reliability and validity in osteoporosis patients from mainland Chinese population. Postmenopausal osteoporosis women with history of vertebral fracture were included as cases, and age-matched healthy female were included as controls. All subjects were from mainland China. The simplified Chinese version of QUALEFFO-31 and SF-36 were assigned to the two groups. Reliability was assessed using kappa statistics of agreement for each item and the intra-class correlation coefficient (ICC). The internal consistency was assessed with Cronbach's alpha. Pearson's correlation was used to assess convergent and discriminant validity. Overall, 66 cases and 66 age-matched controls were included. The ICC for the test-retest reliability ranged from 0.76 to 0.91. Cronbach's alpha for pain, physical function, and mental function domains were 0.94, 0.87, and 0.79, respectively. Convergent validity and discriminant validity showed that each correlation coefficient between score of each item with total score of related domain was higher than that with total score of unrelated domain. Pearson's correlation coefficients indicated significantly high correlations between corresponding domains of QUALEFFO-31 and SF-36. The simplified Chinese version of the QUALEFFO-31 is a reliable and valid outcome measure of functional status in patients with osteoporosis. This Chinese version of the QUALEFFO-31 can be utilized for future clinical studies in mainland China.