Development and validation of the mini-osteoporosis quality of life questionnaire (OQLQ) in osteoporotic women with back pain due to vertebral fractures. Osteoporosis Quality of Life Study Group

The objective of the study was to evaluate a shortened osteoporosis quality of life questionnaire (OQLQ) in osteoporotic women with back pain due to vertebral fractures. From the longer 30-item OQLQ (four to nine items per domain) we created the mini-OQLQ by choosing the two items with the highest impact in each of five domains (symptoms, physical function, activities of daily living, emotional function, leisure). We administered the OQLQ, the Sickness Impact Profile, the SF-36 and the Brief Pain Index to patients at baseline, after 2 weeks and after 6 months. The intraclass correlations between baseline and the 2-week follow-up for the five mini-OQLQ domains ranged from 0.72 to 0.86. Cross-sectional correlations between the domains of the mini-OQLQ and other health instruments were moderate to large (0.35-0.80) and greater than predicted. The mini-OQLQ items showed moderate to large correlations with items omitted from the shortened questionnaire (0.44-0.8). Correlations between the OQLQ domains and the other three instruments were greater than those of the mini-OQLQ, and partial correlations between OQLQ items omitted from the mini-OQLQ and the other three instruments after considering mini-OQLQ items were substantial (0.19-0.71) and statistically significant. Sample sizes of less than 200 per group should be required to detect minimally important differences in parallel-group clinical trials. Longitudinal correlations between the mini-OQLQ and the other measures were often significant but generally lower than predicted (0.10-0.49). The partial correlations revealed that the omitted items explained a significant portion of the longitudinal variance in each domain. We conclude that in a selected group of patients with back pain caused by vertebral fractures, the mini-OQLQ demonstrated good discriminative and adequate evaluative properties. The mini-questionnaire should be useful in clinical settings.