BMD monitoring of bisphosphonate therapy not needed during first 3 years

Postmenopausal women treated with alendronate may not need bone mineral density monitoring within the first 3 years of starting treatment because such tests can give misleading results, according to a study published online on June 23 in BMJ.

Katy J.L. Bell, of the University of Sydney in Australia, and colleagues conducted a trial of 6,459 postmenopausal women with low bone mineral density who were randomized to receive either placebo or the bisphosphonate alendronate, and who were followed up to undergo hip and spine bone density measurements 1, 2, and 3 years later.

After 3 years of treatment, hip bone mineral density increased by a mean .030 g/cm² and treatment gave 97.5% of patients an increase of at least .019 g/cm², the researchers found. But even though the researchers found that the effects of the drug varied between individuals during the first 3 years of treatment, the size of the variation wasn’t clinically significant, which prompted them to conclude that BMD monitoring wouldn’t reveal anything significant for individual patients.

“Clinicians may cite other reasons for monitoring besides estimating the intended effects of treatment,” the authors write. “One common reason given is to assess adherence to treatment. However, the large background within-person variation for bone mineral density means that monitoring is unlikely to give reliable information about whether the drugs were taken as prescribed.”

The study was supported by Merck. Authors reported relationships with Merck and other pharmaceutical companies.

Bell KJ, Hayen A, Macaskill P, et al. Value of routine monitoring of bone mineral density after starting bisphosphonate treatment: secondary analysis of trial data. BMJ. 2009;338:b2266. doi: 10.1136/bmj.b2266.