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


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


METHODS
The authors searched Central, Medline, and EMBASE for relevant randomized controlled trials published from 1966 to 2007.


METHODS
The authors undertook study selection and data abstraction in duplicate. The authors performed meta-analysis of fracture outcomes using relative risks, and a relative change greater than 15 percent was considered clinically important. The authors assessed study quality through reporting of allocation concealment, blinding, and withdrawals.


RESULTS
Eleven trials representing 12,068 women were included in the review. Relative and absolute risk reductions for the 10-mg dose were as follows. For vertebral fractures, a 45 percent relative risk reduction was found (relative risk [RR] = 0.55; 95% confidence interval [CI], 0.45 to 0.67). This was significant for primary prevention, with a 45 percent relative risk reduction (RR = 0.55; 95% CI, 0.38 to 0.80) and 2 percent absolute risk reduction; and for secondary prevention, with 45 percent relative risk reduction (RR = 0.55; 95% CI, 0.43 to 0.69) and 6 percent absolute risk reduction. For nonvertebral fractures, a 16 percent relative risk reduction was found (RR = 0.84; 95% CI, 0.74 to 0.94). This was significant for secondary prevention, with a 23 percent relative risk reduction (RR = 0.77; 95% CI, 0.64 to 0.92) and a 2 percent absolute risk reduction, but not for primary prevention (RR = 0.89; 95% CI, 0.76 to 1.04). There was a 40 percent relative risk reduction in hip fractures (RR = 0.60; 95% CI, 0.40 to 0.92), but only secondary prevention was significant, with a 53 percent relative risk reduction (RR = 0.47; 95% CI, 0.26 to 0.85) and a 1 percent absolute risk reduction. The only significance found for wrist fractures was in secondary prevention, with a 50 percent relative risk reduction (RR = 0.50; 95% CI, 0.34 to 0.73) and a 2 percent absolute risk reduction. For adverse events, the authors found no statistically significant difference in any included study. However, observational data raise concerns about potential risk for upper gastrointestinal injury and, less commonly, osteonecrosis of the jaw.


CONCLUSIONS
At 10 mg of alendronate per day, clinically important and statistically significant reductions in vertebral, nonvertebral, hip, and wrist fractures were observed for secondary prevention. The authors found no statistically significant results for primary prevention, with the exception of vertebral fractures, for which the reduction was clinically important.
Holder
Kathryn K
KK
David Grant Medical Center, Family Medicine Residency Program, Travis AFB, California, USA. kathryn.holder-02@travis.af.mil
Kerley
Sara Shelton
SS
D019386:Alendronate / Q000627:therapeutic use*; D050071:Bone Density Conservation Agents / Q000627:therapeutic use*; D005260:Female; D005598:Fractures, Spontaneous / Q000517:prevention & control*; D006801:Humans; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000150:complications*
D050071:Bone Density Conservation Agents; D019386:Alendronate