Quality of life in postmenopausal women with reduced bone mineral density: psychometric evaluation of the Polish version of QUALEFFO-41

INTRODUCTION: Evaluation of the quality of life of patients with osteoporosis concerns the physical, emotional, social and pain quality of life domains. The aim of the research was to describe the psychometric properties of the Polish version of QUALEFFO-41 in 253 Polish postmenopausal women with osteopenia or osteoporosis and in 132 postmenopausal women with normal BMD. MATERIAL AND METHODS: The internal reliability of QUALEFFO-41 was studied using Cronbach’s alpha coefficient. The reproducibility of the QUALEFFO-41 scales was assessed using Pearson’s correlation. The capacity of questions to discriminate between women with reduced bone mineral density (BMD) and normal subjects was assessed by conditional logistic regression to derive an odds ratio with 95% confidence intervals. The discriminative power, which measures the ability of the questionnaire to discriminate between patients, was assessed by clinical validity. Additionally, receiver operating characteristic (ROC) curves were constructed to assess the ability of QUALEFFO-41. RESULTS: Cronbach’s α coefficient reflecting the reliability and repeatability of the instrument for all domains was satisfactory. Results of scores for domains of QUALEFFO-41 and the score for total QUALEFFO-41 demonstrate a significant difference (p < 0.001) among all groups; only in the case of the pain domain was there a significant difference at the level of p < 0.01 between normal subjects and osteoporotic patients. Receiver operating characteristic curve analysis demonstrated a good discriminating capacity of individual domains and total QUALEFFO-41 score. CONCLUSIONS: The Polish version of QUALEFFO-41 can be used among patients with reduced BMD compared to normal subjects, independently of vertebral fractures, as it is coherent and discriminates well between women with reduced BMD and normal subjects.