An Outcome Measure of Functionality and Quality of Life in Patients with Osteoporotic Vertebral Fracture: A Validation Study of the QUALEFFO-41

Abstract

Background: Osteoporosis is a very common disease of bone, and vertebral fracture. The Quality of Life Questionnaire of the European Foundation for Osteoporosis (QUALEFFO-41) is a tool of health related quality of life in these patients. This study aimed to cross-culturally translate and validate the QUALEFFO-41 in Iran.

Materials and Methods: This was a prospective clinical validation study. Forward-backward procedure was used to translate the questionnaire from English into Persian. The translation and cross-cultural adaptation was made in accordance with published guidelines. Patients were divided into two study groups, according to World Health Organization criteria: with at least one vertebral fracture, which had been surgery and with OP and no fractures as a control group. All of the participants were assessed by both QUALEFFO-41 and SF-36. Surgery group was asked to respond to the QUALEFFO-41 at two points in time: pre- and postoperative assessments (6 months follow-up). To test reliability the internal consistency was evaluated using Cronbach's alpha coefficient. Validity was evaluated by performing convergent validity between the QUALEFFO-41 and the 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: In all 149 patients were completed the questionnaire, 48 patients with surgery, and 101 patients as a control group. The QUALEFFO-41 at pre- and postoperative assessments 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 of the QUALEFFO-41 indicated acceptable results suggesting that the items had a substantial relationship with its own domain. Further analysis also indicated that the questionnaire was responsive to change (P < 0.0001). Significant correlations existed between scores of similar subscales of QUALEFFO-41 and the SF-36 (P < 0.001).

Conclusions: The findings show that, the Iranian version of QUALEFFO-41 is a reliable and valid measure of functionality and quality of life evaluation among patients with osteoporotic vertebral fracture.

 Keywords: QUALEFFO-41, Measure, Osteoporotic vertebral fracture