Dennis M. Black, Ph.D., of the University of California, San Francisco, and colleagues report from a study, which was designed to evaluate the effects on BMD of either continuation of alendronate, 5 or 10 mg/d for a total of ten years, or discontinuation after approximately five years. The trial was conducted at ten clinical centers, and 1,099 postmenopausal women were randomised to: alendronate, 5 mg/d (n = 329) or 10 mg/d (n = 333), or placebo (n = 437) for five years (1998-2003).

The researchers found that compared with continuing alendronate, switching to placebo for five years resulted in declines in BMD at the total hip (-2.4 percent) and spine (-3.7 percent), but average levels remained at or above pretreatment levels ten years earlier. Similarly, those discontinuing alendronate had increased serum markers of bone turnover compared with continuing alendronate, but after five years without therapy, bone marker levels remained somewhat below pretreatment levels ten years earlier. After five years, the cumulative risk of nonvertebral fractures was not significantly different between those continuing (19 percent) and discontinuing (18.9 percent) alendronate. Among those who continued, there was a 55 percent lower risk of clinically recognized vertebral fractures.

"These results suggest that for many women, discontinuation of alendronate after five years for up to five more years does not significantly increase fracture risk, but women at high risk of clinical vertebral fractures, such as those with vertebral fracture or very low BMD, may benefit by continuing beyond five years," the researchers write.

MEDICA.de; Source: American Medical Association (AMA)