Alendronate for the primary and secondary prevention of osteoporotic fractures in postmenopausal women

Evidence Summaries

Level of Evidence = A
Alendronate reduces vertebral, non-vertebral, hip and wrist fractures in women with low bone density and with a previous fracture, but in primary prevention of osteoporotic fractures it seems only to reduce vertebral fractures.

A Cochrane review 1 included 11 studies with a total of 12,068 subjects. Relative (RRR) and absolute (ARR) risk reductions for the 10 mg dose were as follows. For vertebral fractures, a significant 45% RRR was found (RR 0.55, 95% CI 0.45 to 0.67). This was significant for both primary prevention, with 45% RRR (RR 0.55, 95% CI 0.38 to 0.80) and 2% ARR, and secondary prevention with 45% RRR (RR 0.55, 95% CI 0.43 to 0.69) and 6% ARR. For non-vertebral fractures, a significant 16% RRR was found (RR 0.84, 95% CI 0.74 to 0.94). This was significant for secondary prevention, with 23% RRR (RR 0.77, 95% CI 0.64 to 0.92) and 2% ARR, but not for primary prevention (RR 0.89, 95% CI 0.76 to 1.04). There was a significant 40% RRR in hip fractures (RR 0.60, 95% CI 0.40 to 0.92), but only secondary prevention was significant with 53% RRR (RR 0.47, 95% CI 0.26 to 0.85) and 1% ARR. The only significance found for wrist was in secondary prevention, with a 50% RRR (RR 0.50 95% CI 0.34 to 0.73) and 2% ARR. For adverse events, no statistically significant differences were found in any included study. However, observational data raise concerns regarding potential risk for upper gastrointestinal injury and, less commonly, osteonecrosis of the jaw.

Comment: The quality of evidence is downgraded by study quality (unclear allocation concealment and more than 20% loss to follow-up in some studies) and upgraded by consistent findings.

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References

1. Wells GA, Cranney A, Peterson J, Boucher M, Shea B, Robinson V, Coyle D, Tugwell P. Alendronate for the primary and secondary prevention of osteoporotic fractures in postmenopausal women. Cochrane Database Syst Rev 2008 Jan 23;(1):CD001155.  [PMID:18253985]

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