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

Wells GA, Cranney A, Peterson J, Boucher M, Shea B, Robinson V, Coyle D, Tugwell P

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Summary

Alendronate for preventing fractures caused by osteoporosis in postmenopausal women

This summary of a Cochrane review presents what we know from research about the effect of alendronate for preventing fractures (broken bones) caused by osteoporosis.

In women who have already been diagnosed with low bone density, putting them at risk for a fracture, or have already had a fracture in the bones of their spine, alendronate:

may prevent fractures in the spine, hip or wrist, or in bones other than the spine.

In women whose bone density is closer to normal, or who may not yet have had a fracture in the bones of their spine, alendronate:

probably prevents fractures in the spine
probably leads to no difference in fractures of the hip, wrist or bones other than the spine.

We often do not have precise information about side effects and complications. This is particularly true for rare but serious side effects. Possible side effects may include digestive problems such as injury to the throat, esophagus and stomach and, less commonly, reduced blood supply to the jaw bone, which causes the bone tissue to break down.

What is osteoporosis and what is alendronate?
Bone is a living, growing part of your body. Throughout your lifetime, new bone cells grow and old bone cells break down to make room for the new, stronger bone. When you have osteoporosis, the old bone breaks down faster than the new bone can replace it. As this happens, the bones lose minerals (such as calcium). This makes bones weaker and more likely to break even after a minor injury, like a little bump or fall. Women who have gone through menopause are more likely to get osteoporosis than other people.

Alendronate belongs to the class of drugs called bisphosphonates. It is a type of medication that slows down the cells that break down the old bone.

The best estimate of what happens to women that have already been diagnosed with low bone density, putting them at risk of a fracture, or have already had a fracture in the bones of their spine, who take alendronate:

six fewer patients out of 100 had a fracture of the spine
one fewer patient out of 100 had a fracture in the hip or wrist
two fewer patients out of 100 had fractures in bones other than the spine

The best estimate of what happens to women whose bone density is closer to normal, or who may not yet have had a fracture in the bones of their spine, who take alendronate:

two fewer patients out of 100 had a fracture in the bones of the spine
no difference in the number of women who had hip fractures; one more patient out of 100 had a wrist fracture, and one fewer person out of 100 had a fracture in the bones other than the spine. This may be the result of chance.

This is a Cochrane review abstract and plain language summary, prepared and maintained by The Cochrane Collaboration, currently published in The Cochrane Database of Systematic Reviews 2008 Issue 3, Copyright © 2008 The Cochrane Collaboration. Published by John Wiley and Sons, Ltd.. The full text of the review is available in The Cochrane Library (ISSN 1464-780X).
This record should be cited as: 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 of Systematic Reviews 2008, Issue 1. Art. No.: CD001155. DOI: 10.1002/14651858.CD001155.pub2

This version first published online: January 23. 2008

Abstract

Background

Osteoporosis is an abnormal reduction in bone mass and bone deterioration leading to increased fracture risk. Alendronate belongs to the bisphosphonate class of drugs, which act to inhibit bone resorption by interfering with the activity of osteoclasts.

Objectives

To assess the efficacy of alendronate in the primary and secondary prevention of osteoporotic fractures in postmenopausal women.

Search strategy

We searched CENTRAL, MEDLINE and EMBASE for relevant randomized controlled trials published between 1966 to 2007.

Selection criteria

Women receiving at least one year of alendronate, for postmenopausal osteoporosis, were compared to those receiving placebo and/or concurrent calcium/vitamin D. The outcome was fracture incidence.

Data collection and analysis

We undertook study selection and data abstraction in duplicate. We performed meta-analysis of fracture outcomes using relative risks and a > 15% relative change was considered clinically important. We assessed study quality through reporting of allocation concealment, blinding and withdrawals.

Main results

Eleven trials representing 12,068 women were included in the review.

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, we found no statistically significant differences in any included study. However, observational data raise concerns regarding potential risk for upper gastrointestinal injury and, less commonly, osteonecrosis of the jaw.

Authors' conclusions

At 10 mg per day, both clinically important and statistically significant reductions in vertebral, non-vertebral, hip and wrist fractures were observed for secondary prevention ('gold' level evidence, www.cochranemsk.org). We found no statistically significant results for primary prevention, with the exception of vertebral fractures, for which the reduction was clinically important ('gold' level evidence).

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