Risedronate for the Prevention of Osteoporotic Fractures in Postmenopausal Women

Summary

A Cochrane review [Abstract] 1 included 33 studies with a total of 27 348 postmenopausal women. A study was classified as secondary prevention if it recruited postmenopausal women who fulfilled more than one of the hierarchical criteria denoting a higher risk of fractures: a diagnosis of osteoporosis, a history of vertebral fractures, low bone mineral density T score ≤ -2.5, and/or age≥ 75 years old. If the study included postmenopausal women who did not meet any of the above criteria, it was considered to be primary prevention (for women at lower risk of fractures).

Primary prevention (4 studies, n=989, 1 to 2 years in length): risedronate 5 mg/day did not have statistically siginificant difference to wrist fractures (RR 0.48, 95% CI 0.03 to 7.50; 2 studies, n=243) and withdrawals due to adverse events (RR 0.67, 95% CI 0.38 to 1.18; 3 studies, n=748). There were zero clinical vertebral and hip fractures reported therefore the effects of risedronate for these outcomes were not estimable. Secondary prevention (9 studies, n=14 354, 1 to 3 years in length): risedronate 5 mg/day prevented non-vertebral fractures (RR 0.80, 95% CI 0.72 to 0.90; 6 studies, n=12 173; absolute risk reduction, ARR 2% fewer, 95% CI 1% fewer to 3% fewer), and hip fractures (RR 0.73, 95% CI 0.56 to 0.94; ARR 1% fewer, 95% CI 0.2% fewer to 1% fewer). Both of these effects are probably clinically important. Risedronate did not have statistically significant effect for wrist fractures (RR 0.64, 95% CI 0.33 to 1.24; 3 studies, n=1 746) and the effect was not estimable for clinical vertebral fractures due to zero events reported. There were not differences in withdrawals due to adverse events (RR 0.98, 95% CI 0.90 to 1.07; 8 studies, n=9 529) and in serious adverse events (RR 1.00, 95% CI 0.94 to 1.07; 6 studies, n=9 435).

Risedronate 5 mg/day versus the therapeutic equivalents: Four secondary prevention studies reported at least one outcome of interest. The null hypotheses of no difference between risedronate 5 mg/day and its therapeutical equivalents (35 mg/week, 75 mg on two consecutive days each month and 150 mg/month) in the benefits and harms were not rejected, except for 2 exceptions. Fewer women treated with daily 5 mg versus monthly 150 mg experienced serious adverse events. The estimate of the RR was 0.67 (95% CI 0.48 to 0.94). One study observed that fewer women receiving daily risedronate (5 mg) than those receiving monthly risedronate (150 mg) experienced acute phase reactions, with the RR of 0.11 (95% CI 0.01 to 0.89).