RESUMO
CONTEXT: The evidence for relative effectiveness of osteoporosis drugs in secondary prevention of nonvertebral fractures was unclear and could not be extrapolated to the Asian population. OBJECTIVE: The objective of the study was to compare the relative effectiveness of different classes of osteoporosis drugs in secondary prevention of nonvertebral fractures in Taiwanese women. DESIGN: This was a retrospective cohort study from 2003 to 2007, with up to 6 years of follow-up. SETTING: The study included enrollees in Taiwan National Health Insurance. PATIENTS: Patients older than 50 years, with vertebral/hip fracture and were new to osteoporosis therapy, were recruited. INTERVENTION: Patients were classified into the alendronate, calcitonin, or raloxifene group, according to their exposure after follow-up. MAIN OUTCOME MEASURE: The primary outcome of our study was the risk of incident nonvertebral fracture (hip, humerus, or radius fractures). A multivariate Cox proportional hazard model adjusted for fracture risk factors was used to compare the relative fracture risk among three treatment groups under on-treatment scenarios. Propensity score-matched hazard ratios were examined, and interactions between fracture incidence and patients' compliance were investigated as well. RESULTS: There were 19 840, 9534, and 25 483 patients in the alendronate, raloxifene, and calcitonin groups, respectively. The fracture rates were highest in calcitonin recipients (4.57 per 100 person-years), followed by raloxifene and alendronate. Results from Cox analyses showed raloxifene (hazard ratio 1.47; 95% confidence interval 1.29-1.67) and calcitonin (hazard ratio 1.51; 95% confidence interval 1.29-1.75) had higher nonvertebral fracture risks as compared with alendronate. The risk differences were more pronounced in compliant patients. CONCLUSION: We found alendronate users had the lowest secondary nonvertebral fracture risk, as compared with raloxifene and calcitonin users. Consistent results were found in a series of sensitivity analyses.