An outcome measure of functionality and quality of life in Iranian women with osteoporotic vertebral fractures: a validation study of the QUALEFFO-41

Background Osteoporosis is a very common disease and often results in vertebral fractures. The Quality of Life Questionnaire of the European Foundation for Osteoporosis (QUALEFFO-41) is a tool to measure health-related quality of life in these patients. This study aimed to cross-culturally translate and validate the QUALEFFO-41 in Iran. Methods This was a prospective clinical validation study. A forward-backward procedure was used to translate the questionnaire from English into Persian. The translation and cross-cultural adaptation were made in accordance with published guidelines. Patients were divided into two study groups according to the World Health Organization criteria: those with at least one vertebral fracture who had undergone surgery and those with osteoporosis and no fractures as a control group. All of the participants were assessed by both the QUALEFFO-41 and SF-36. The surgery group was asked to respond to the QUALEFFO-41 at two points in time: the pre- and postoperative assessments (6-month follow-up). To test reliability, the internal consistency was evaluated using Cronbach's alpha coefficient. Validity was evaluated by assessing convergent validity between the QUALEFFO-41 and SF-36 and item-scale correlations and discriminatory ability. Internal responsiveness of the QUALEFFO-41 to the clinical intervention (surgery) also was evaluated comparing patients' pre- and postoperative scores. Results A total of 149 patients completed the questionnaire: 48 surgical patients and 101 as a control group. At the pre- and postoperative assessments, the QUALEFFO-41 showed adequate internal consistency in all domains (Cronbach's alpha of 0.71 to 0.81). Additionally, the correlation of each item with its hypothesized domain on the QUALEFFO-41 indicated acceptable results, suggesting that the items had a substantial relationship with their own domains. Further analysis also indicated that the questionnaire was responsive to change (P<.0001). Significant correlations existed between scores of similar subscales of the QUALEFFO-41 and SF-36 (P<0.001). Conclusions The findings show that the Iranian version of the QUALEFFO-41 is a reliable and valid measure of functionality and quality-of-life evaluation among patients with osteoporotic vertebral fractures.