Effects of 15 Years of Continuous Treatment with Bisphosphonate on Japanese Postmenopausal Osteoporosis Patients: An Observational Study.

Bisphosphonate (BP) is mainly used for the treatment of osteoporosis because of its efficacy in increasing bone mineral density (BMD) and reducing osteoporotic fractures. Previous large-scale studies indicated that continuous 10-year treatment with BP was effective for osteoporosis treatment. However, several studies indicated an increase in the risk of serious adverse events such as atypical femoral fracture on prolonged BP treatment. The benefits and risks associated with long-term BP therapy are controversial. On the other hand, the effects of BP for more than 10 years are unknown because of few previous studies. The aim of this study to investigate effects of continuous 15-year treatment with BP on Japanese postmenopausal osteoporosis patients. The study was a retrospective observational study. Fifteen of the 55 patients, who had already received a 10-year course of oral BP treatment in our previous study, continued the treatment for an additional 5 years. All patients made the choice additional BP treatment with informed consent. BMD; hip structural analysis (HSA); limbs-muscle volume; and serum total alkaline phosphatase, tartrate-resistant acid phosphatase-5b, calcium and phosphate levels were measured for 5 years in the 15 patients. BMD values at the lumbar spine were significantly increased at 15 years in comparison with that at 10 years. Section modulus of HSA for the intertrochanter was significantly increased at 15 years. No subsequent fractures or serious adverse events were observed. We demonstrated favorable effects of an additional 5 years of BP treatment in postmenopausal osteoporosis patients who had already received a continuous 10-year treatment.