Protective effect of β blockers in postmenopausal women: Influence on fractures, bone density, micro and macroarchitecture

Introduction: Animal studies suggest that bone remodeling is under β-adrenergic control via the sympathetic nervous system. β blockers have been suggested to stimulate bone formation and/or inhibit bone resorption in animals as well as to reduce the risk of fracture in humans. The purpose of this study was to examine if these agents can have a preventive or therapeutic effect in osteoporosis. Materials and methods: We have studied the association of β blockers use with BMD, bone geometry, microarchitecture and fractures rates in postmenopausal women referred for bone density testing. From a total sample of 944 women, we identified 158 women who were taking β blockers and 341 age-matched women as controls. Bone geometry was investigated at the femoral neck on DXA images. Microarchitecture was evaluated by the H mean fractal parameter at the calcaneus. Results: The odds ratio for fracture (at all sites) in the β blocker users was 0.56 (95% CI, 0.30–0.99). β blocker use was associated with a higher BMD at the femoral neck (+ 4.2%, p < 0.05) and L1–L4 (+ 3.2%, p < 0.05). Proximal femur scans revealed significantly higher cortical width (+ 3.6%, p < 0.05) at the femoral neck under β blockers. Femoral shaft measurement did not significantly differ under β blockers. Medication use and lifestyle factors indicated no association between β blockers and smoking, alcohol use, physical activity, corticosteroids and estrogen therapies. The H mean parameter was significantly higher in the β blockers group (0.619 ± 0.029 vs. 0.607 ± 0.023 in controls, p < 0.05), suggesting a better trabecular microarchitectural organization. Conclusion: Our data suggest that the association of current use of β blockers with low fracture risk is mediated, at least in part, by effects on BMD, cortical bone geometry and trabecular bone microarchitecture.