Safety and efficacy of risedronate in reducing fracture risk in osteoporotic women aged 80 and older: implications for the use of antiresorptive agents in the old and oldest old.

OBJECTIVES: To determine the efficacy of risedronate in reducing vertebral fracture risk in women aged 80 and older with osteoporosis.

DESIGN: Pooled analysis of data from three randomized, double-blind, controlled, 3-year-fracture-endpoint trials conducted from November 1993 to April 1998: Hip Intervention Program (HIP), Vertebral Efficacy with Risedronate Therapy-Multinational (VERT-MN), and VERT-North America (NA).

SETTING: Office-based practices, research centers, and osteoporosis clinics in Europe, North America, and Australia.

PARTICIPANTS: Osteoporotic (femoral neck bone mineral density T-score < -2.5 standard deviations or at least one prevalent vertebral fracture) women aged 80 and older.

INTERVENTION: Patients received placebo (n=688) or risedronate 5 mg/d (n=704) for up to 3 years. All patients received 1,000 mg/d calcium and, if baseline levels were low, up to 500 IU/d vitamin D.

MEASUREMENTS: Cumulative incidence of new vertebral fractures.

RESULTS: After 1 year, the risk of new vertebral fractures in the risedronate group was 81% lower than with placebo (95% confidence interval=60-91%; P<.001). The number of women who needed to be treated to prevent one new vertebral fracture after 1 year was 12. This early onset of efficacy was consistent across the clinical programs, and antifracture efficacy was confirmed over 3 years. Risedronate was well tolerated, with a safety profile comparable with that of placebo.

CONCLUSION: These findings provide the first evidence that, even in the very old, reducing bone resorption rate remains an effective treatment strategy for osteoporosis. Because each therapeutic agent used for the treatment of osteoporosis may have unique characteristics, the observations made in this study should not be assumed to apply to other bisphosphonates.