Comparison of risedronate to alendronate and calcitonin for early reduction of nonvertebral fracture risk: results from a managed care administrative claims database.

OBJECTIVE: Recent randomized clinical trials have shown that risedronate reduces the risk of nonvertebral fractures and clinical vertebral fractures within 6 months of initiating treatment. The objective of the current study was to determine whether this early antifracture effect could be demonstrated in nonvertebral fractures for risedronate and other osteoporosis therapies in an observational administrative claims database.
METHODS: A proprietary administrative claims database was used to identify managed care members who received a new prescription for risedronate, alendronate, or nasal calcitonin from July 1, 2000, to December 31, 2001. Patient records were analyzed for the incidence of nonvertebral fractures (clavicle, humerus, wrist, pelvis, hip, and leg) in the first 6 and 12 months following initiation of treatment. A Cox proportional hazards regression model was used to estimate relative risk (RR) of fracture at 6 and 12 months.
RESULTS: In the 6-month analysis, 774 patients (11%) received calcitonin, 5,307 (75%) received alendronate, and 1,000 (14%) received risedronate. Twelve-month data were available for a subset (71%) of patients (656 calcitonin [13%], 3,716 alendronate [74%], and 652 risedronate [13%]). Most were women (93%); mean age was similar for alendronate and risedronate, and nasal calcitonin patients were about 3 years older, on average. Risedronate and alendronate patients were more likely to have used estrogen, while nasal calcitonin patients were more likely to have been hospitalized and had higher use of concomitant medications and more physician visits. Relative risks were adjusted for these differences. Risedronate and alendronate patients were similar with respect to these indicators of general health status. In the 6-month analysis, nonvertebral fractures were observed in 2.2% of patients receiving nasal calcitonin, 1.4% of patients receiving alendronate, and 0.6% of patients receiving risedronate. The adjusted RR reduction was 69% for risedronate versus calcitonin (RR = 0.31; 95% CI, 0.12 to 0.81; P = 0.02), 54% for risedronate versus alendronate (RR = 0.46; 95% CI, 0.20 to 1.06; P = 0.07), and 26% for alendronate versus calcitonin (RR = 0.74; 95% CI, 0.43 to 1.27; P = 0.28). In the 12-month analysis, nonvertebral fracture rates were 2.9% for nasal calcitonin, 2.4% for alendronate, and 0.9% for risedronate patients. The adjusted RR reduction was 75% for risedronate versus calcitonin (RR = 0.25; 95% CI, 0.10 to 0.64; P<0.01), 59% for risedronate versus alendronate (RR = 0.41; 95% CI, 0.18 to 0.94; P = 0.04), and 25% for alendronate versus calcitonin (RR = 0.75; 95% CI, 0.45 to 1.25; P = 0.27).
CONCLUSIONS: This analysis of medical and pharmacy claims contained in an administrative database confirms the early fracture reduction with risedronate that was shown in randomized clinical trials. Risedronate was more effective than calcitonin in reducing the risk of nonvertebral fractures within the first 6 months of treatment. Risedronate was more effective than either calcitonin or alendronate in reducing the risk of nonvertebral fractures within 12 months of treatment.