Non-vertebral (NV) fractures are responsible for a great amount of morbidity, mortality and cost attributable to osteoporosis.
To identify risk factors for NV fractures in postmenopausal women with osteoporosis, and to design an assessment tool for prediction of these fractures.
2546 postmenopausal women with osteoporosis included in the placebo groups of three risedronate controlled trials were included (mean age 72 years, mean femoral T-score -2.5; 60% and 53% of patients with prevalent vertebral and NV fractures, respectively). Over 3 years, 222 NV fractures were observed. Baseline data on 14 risk factors were included in a logistic regression analysis.
6 risk factors were associated with NV fracture risk: prevalent NV fracture (p = 0.004), number of prevalent vertebral fractures (p<0.001), femoral T-score (p = 0.031), serum level of 25-hydroxyvitamin D (p<0.001), age (p = 0.012) and height (p = 0.037). An NV risk index was developed by converting the multivariate logistic equation into an additive score. In the group of women with a score > or =2.1, the incidence of NV fracture was 13.2% (95% CI 11.1 to 15.3), 1.5 times higher than that of the general population.
The NV risk index is a convenient tool for selection of patients with osteoporosis with a high risk for NV fractures, and may help to choose from available treatments those with a proven efficacy for reduction of NV fracture risk.