Abstract 604 Risedronate 35 mg Once a Week is as Effective as 5 mg Daily in Postmenopausal Women.
R Lindsay, D Kendler, M McClung, A Balske, Z Li, J Brown. New York, Canada, Oregon, Ohio.

The purpose of this randomized, double-blind study was to compare the efficacy of 35mg and/or 50mg of risedronate taken once per week with 5mg risedronate taken once daily for the treatment of osteoporosis. These are the 1st year results of a 2 year trial.

Methods: The 1450 women enrolled in the study had a mean age of 68, were >5 years postmenopausal, and had a lumbar spine (LS) bone mass density (BMD) T-score of >-2.5 or >-2.0 with at least one prevalent vertebral fracture. Patients were treated with risedronate at a dose of 5mg once daily, 35mg once weekly, or 50mg once weekly. Patients taking the once weekly dose were given placebo on the remaining 6 days in order to maintain blindedness of treatment. All patients were given calcium. Vitamin D was also given if serum vitamin D levels were <30 nmoles/L. Patients were included in the analysis if they took at least one dose of study medication.

Results: At 12 months, the 35 and 50mg once weekly dosing and 5mg once daily dosing were equally effective at increasing the lumbar spine (LS) bone mass density (BMD) from baseline, 4%, 3.94%, and 4.25%, respectively. Total hip, femoral neck, and trochanteric BMD also increased significantly in all 3 groups. Bone turnover markers, bone alkaline phosphatase (BAP) and NTx/creatinine were significantly reduced by 3 months in all groups and remained so at 12 months.

These results indicate that 35 and 50 mg once weekly of risedronate is as efficacious as a 5 mg dose at increasing BMD in postmenopausal women, with no significant difference in benefit between the 50 mg and 35 mg dose.

Editorial Comments: The once weekly dosing is more convenient for the patient and presumably less GI toxic. The results on BMD are encouraging, but the 2-year data will provide the most important data on outcome - that is, whether the once weekly dosing reduces risk for subsequent fractures.

Abstract 605 Effects of Vitamin D and Calcium Supplementation on Falls: A Randomized Controlled Trail.
H Bischoff, H Staehelin, W Dick, R Akos, R Theiler, R Lew, M Conzelmann. Switzerland, Boston, MA.

Previous studies in elderly patients have shown that a higher serum vitamin D level correlates with greater muscle strength and fewer falls. This study assessed the number of falls, musculoskeletal function and bone metabolism after 12 weeks of treatment with 1200 mg calcium with (n=62) or without 800 mg vitamin D (n=60) per day. Patients were included in the analysis if they received a minimum of one dose of supplement.

Results: After adjusting for 6 week pre-treatment measurements, the group treated with calcium plus vitamin D had a 49% reduction in falls when compared to the group treated with calcium alone. Significant increases in musculoskeletal function, as well as significant decreases in serum markers for bone metabolism were observed in the calcium plus vitamin D group when compared to the calcium alone group. Limits to this study include a 28% loss to follow-up, although equal in both groups, and a limited patient population of elderly caucasian women who were vitamin D deficient. Additionally, although the total number of falls was reduced, the actual number of persons who fell in each group was not significantly different.

These data indicate that calcium plus vitamin D can reduce the risk of falling in elderly, caucasian women. This reduction in falls may be a result of increased musculoskeletal function and/or decreased bone metabolism.

Abstract 609 The Influence of Anthrometric Factors on the Risk of Incident Vertebral Fracture.
D Roy, J Finn, D Felsenberg, O Johnell, M Lunt, T O'Neill, J Reeve, A Siman. United Kingdom, Germany, Sweden.

This multicenter, prospective study of 3228 men and 3456 women was designed to assess if height, weight, and body mass index (BMI) were predictive of osteoporotic vertebral fractures. Lateral thoracolumbar radiographs were taken at baseline and a mean of 3.8 years later, accounting 24,624 person follow up years.

Results: Using Poisson regression analysis, results indicated that the lowest quintiles of weight and BMI were significantly associated with risk of vertebral fracture, (RR=1.45 and RR=1.5, respectively). Height had no predictive value on the risk of fracture.

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