36 month intermittent cyclical etidronate treatment in patients with established corticosteroid induced osteoporosis.

OBJECTIVE: To determine the longterm safety and efficacy of etidronate therapy in patients in whom corticosteroid induced bone loss has already occurred. METHODS: We performed a 36 month observational cohort study in which all data were obtained from Canadian Database of Osteoporosis and Osteopenia (CANDOO) patients. The etidronate group consisted of 24 patients who received 400 mg of etidronate disodium for 14 days, followed by 76 days of calcium carbonate (500 mg of elemental calcium), repeated every 3 mo; the control group included 37 patients who received calcium carbonate 500 to 1000 mg daily. Outcome measurements included changes within groups from baseline and differences between groups in the bone mineral density (BMD) of the lumbar spine, femoral neck, and trochanter at 12, 24, and 36 months. The incidence of vertebral fractures was also determined. RESULTS: Etidronate therapy resulted in a meaningful percentage increase from baseline in lumbar spine BMD, primarily during the first 24 months of treatment, and this increase was sustained for the remainder of the 36 month study period (5.2%; p = 0.016). Analysis of covariance revealed a significant percentage difference (SD) between groups in lumbar spine BMD at 12 [5.5 (13.5) percent; p = 0.003] and 24 months [6.0 (17.4) percent; p = 0.011] in favor of the etidronate group. After 3 years of therapy, one patient (4%) experienced one vertebral fracture in the etidronate group, whereas 3 patients (8%) experienced 5 vertebral fractures in the control group. CONCLUSION: Etidronate treatment administered for 36 months reversed lumbar spine bone loss, and appeared to be safe in patients with established corticosteroid induced osteoporosis.