Etidronate 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 etidronate for preventing fractures (broken bones) caused by osteoporosis.

In women who 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, etidronate:

-may prevent fractures in the bones of the spine.

- may lead to no difference in hip or wrist fractures or fractures in the bones other than in the spine.

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

- may lead to no difference in fractures in the bones of the spine, or in bones other than those of the spine.

- it is not known whether etidronate prevents hip or wrist fractures since no evidence was found that looked at the effect of etidronate in these women.

 

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 heartburn, nausea and upset stomach.

What is osteoporosis and what is etidronate?
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. Etidronate 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 or have already had a fracture in the bones of their spine:

Fracture of the spine:

                 - 11 out of 100 women had a fracture when taking a placebo

                 - 6 out of 100 women had a fracture when taking etidronate

 

Fractures in bones other than the spine:

                 - 13 out of 100 women had a fracture when taking a placebo

                 - 14 out of 100 women had a fracture when taking etidronate

 

Fractures in the hip or wrist:

                 - there was no difference in the number of women who had hip or wrist fractures which may be the result of chance

 

 

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:

 

Fracture of the spine

                 - 0 out of 100 women had a fracture when taking a placebo

                 - 1 out of 100 women had a fracture when taking etidronate

 

Fractures in bones other than the spine

                 - 11 out of 100 women had a fracture when taking a placebo

                 - 6 out of 100 women had a fracture when taking etidronate

 

For these women, fractures in the hip or wrist were not measured in the studies.

Authors' conclusions: 

Etidronate, at 400 mg per day, demonstrated a statistically significant and clinically important benefit in the secondary prevention of vertebral fractures. No statistically significant reductions in vertebral fractures were observed when it was used for primary prevention. In addition, no statistically significant reductions in non-vertebral, hip, or wrist fractures were found, regardless of whether etidronate was used for primary or secondary prevention. The level of evidence for all outcomes is Silver (www.cochranemsk.org.)

Read the full abstract...
Background: 

Osteoporosis is an abnormal reduction in bone mass and bone deterioration leading to increased fracture risk. Etidronate 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 etidronate 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 etidronate for postmenopausal osteoporosis were compared to those receiving placebo and/or concurrent calcium/vitamin D. The outcome was fracture incidence.

Data collection and analysis: 

Study selection and data abstraction was done in duplicate. Meta-analysis of fracture outcomes was performed with data presented as relative risks and a relative change greater than 15% was considered clinically important. Study quality was assessed through the reporting of allocation concealment, blinding and withdrawals.

Main results: 

Eleven studies representing a total of 1248 patients were included in the review.

A significant 41% relative risk reduction (RRR) in vertebral fractures across eight studies (RR 0.59, 95% CI 0.36 to 0.96) was found. The six secondary prevention trials demonstrated a significant RRR of 47% in vertebral fractures (RR 0.53, 95% CI 0.32 to 0.87) and a 5% absolute risk reduction (ARR); compared with the pooled result for the two primary prevention trials (RR 3.03, 95% CI 0.32 to 28.44), which was not significant. There were no statistically significant risk reductions for non-vertebral (RR 0.98, 95% CI 0.68 to 1.42), hip (RR 1.20, 95% CI 0.37 to 3.88) or wrist fractures (RR 0.87, 95% CI: 0.32 to 2.36).

For adverse events, no statistically significant differences were found in the included studies. However, observational data has led to concerns regarding potential risk for upper gastrointestinal injury.

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