Objective: To evaluate the efficacy of once weekly (OW) alendronate 70 mg compared to OW risedronate 35 mg in a post-hoc subgroup analysis of patients from the FACT study (Fosamax- Actonel- Comparison- Trial) with osteoporosis at baseline. Methods: FACT was a 12 month, randomized, double-blind study of 1053 postmenopausal women with low bone mass (T-score £-2 at total hip, hip trochanter, femoral neck, or lumbar spine). 669 women (63.5%) had osteoporosis as defined by either a T-score £-2.5 at any one of the measured BMD sites (56% of subjects) at entry or a history of a clinical fracture at the hip, spine, or wrist. Subjects had been randomly assigned to OW alendronate 70 mg (N=323) or OW risedronate 35 mg (N=346). The primary endpoint in FACT was the difference between treatments in hip trochanter BMD change at 12 months relative to baseline. Secondary endpoints included differences in total hip, femoral neck, and lumbar spine (LS) BMD at 12 months, and at all BMD sites at 6 months. Results: The mean age of subjects in the osteoporotic subgroup was 65 years; they were primarily Caucasian with a mean time since menopause of 19.6 years. A test for interaction between treatment effect and patient's baseline osteoporosis status was not significant for difference in change at 12 months at any BMD site, indicating consistency of larger response with alendronate, regardless of patient's baseline T-score or history of osteoporotic fracture. Within the osteoporotic subgroup, OW alendronate produced a significantly greater increase from baseline than OW risedronate in hip trochanter BMD at 12 months (3.6% vs 2.1%, respectively, p<0.001) and a greater percent of responders (³0% gain) (85.7% vs 68.2%, respectively, p<0.001). Increases were also significantly greater (p<0.001) at the total hip (2.2% vs 1.2%) and LS (3.8% vs 2.6%), and numerically greater at the femoral neck BMD (1.5% vs 1.0%) at 12 months. Significant differences in BMD increases from baseline (p<0.05) were seen at 6 months at all four sites favoring alendronate compared to risedronate. There were also significantly more responders with alendronate than risedronate at the total hip and lumbar spine. Conclusions: In the subgroup of women with osteoporosis from the FACT trial, treatment with OW alendronate 70 mg produced significantly greater gains in hip and spine BMD and a greater percentage of patients with measured gains than OW risedronate 35 mg. Treatment differences were significant as early as 6 months. These results are consistent with the results of the overall study population.
Disclosure Information:
Faculty Member's Name: Sydney Bonnick, MD
Grants/Research Support: Merck & Co., Inc.
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