Objective: To assess the potential efficacy of intermittent cyclic therapy (ICT) with etidronate in the treatment of patients with corticosteroid induced osteoporosis.

Methods: Cohort study in a tertiary care university affiliated hospital in corticosteroid treated patients, with polymyalgia rheumatica, asthma, systemic lupus erythematosus, rheumatoid arthritis, or temporal arteritis, examining the effects of ICT etidronate. Patients were included if they were taking corticosteroids for a minimum of one year. Comparison patients were those who had been taking corticosteroids for a minimum of one year and who had not been treated with etidronate or other medication which might alter bone metabolism. A total of 68 patients were included from 253 considered. The mean (SD) dose of prednisone in the ICT etidronate treated patients was 9.3 (6.2) mg and in the comparison patients 9.4 (5.9) mg. The duration of prednisone therapy was 7.8 (5.8) years and 3.4 (4.2) years, respectively (p2 < 0.001). An analysis of covariance demonstrated that this difference did not alter our primary outcome measure. The primary outcome measure was the difference in the percentage change from baseline to one year of followup in bone mineral density (BMD) of the lumbar spine between treatment and comparison groups.

Results: ICT etidronate resulted in a statistically significant and clinically important increase in BMD. The BMD of the lumbar spine increased by 3.82% (0.65%), [95% confidence interval (CI), 2.51 to 5.14%] in the 35 ICT etidronate treated patients and decreased by 1.78% (0.76%), [95% CI, -3.34 to -0.23%] in the 33 comparison patients after 12 months (p2 < 0.0001).

Conclusions: ICT etidronate prevented loss of vertebral bone density in patients with corticosteroid induced osteoporosis. Controlled, double blind, prospective trials with longer followup are needed to confirm these results and to demonstrate that increases in bone mass translate into decreased fracture rates.