Hip and subtrochanteric or diaphyseal femoral fractures in alendronate users: A 10-year, nationwide retrospective cohort study in taiwanese women

Background: A link between the use of alendronate and atypical diaphyseal femoral fracture has been suggested. Objective: The goal of this study was to evaluate the benefits of alendronate in preventing rehospitalization due to hip fractures and whether its use increases risk of hospitalization for atypical diaphyseal femoral fractures in Taiwan. Methods: Using Taiwan's National Health Insurance database, we identified women with osteoporosis with a first-ever hospitalization for vertebral or hip fractures between 2001 and 2007, which consisted of all patients receiving alendronate, raloxifene, calcitonin salmon, or teriparatide after the index fracture hospitalization. Data of untreated women were obtained as the untreated cohort. Study outcomes were defined as a rehospitalization due to hip fracture or a new hospitalization for subtrochanteric or diaphyseal femoral fracture. Results: Among 11,278 women identified (mean age, 77 years), 2425 (21.5%) received alendronate, 2694 (23.9%) received other antiosteoporosis drugs, and 6159 (54.6%) were untreated. Patients in each group were comparable in fracture history and major comorbidities; untreated patients were more likely to have stroke (11.2%; P = 0.01) and those treated with alendronate were more likely to have a history of hyperlipidemia (16.2%; P = 0.03). Compared with the untreated patient cohort, our analysis suggested that patients prescribed alendronate were associated with decreased risk of rehospitalization due to hip fracture (hazard ratio = 0.67 [95% CI, 0.54-0.82]). Neither patients prescribed alendronate, nor those prescribed other antiosteoporosis drugs, differed significantly from the untreated patient cohort in terms of risk of hospitalization for atypical femoral fracture (adjusted hazard ratios = 0.77 and 0.49 [95% CI, 0.40-1.47 and 0.22-1.12], respectively). Consistent with these data, short- or long-term alendronate use was not found to be significantly associated with higher risk of atypical femoral fractures. Conclusions: This study in Taiwanese patients suggests that alendronate use was associated with a reduction in risk of rehospitalization due to hip fracture. We did not find a significant association between alendronate use and risk of hospitalization for atypical femoral fracture.