June 25 (HealthDay News) -- Monitoring bone density in older women after they've started taking drugs to prevent osteoporosis is unnecessary and could be potentially misleading, researchers say.

In the study, Australian researchers analyzed data from a large randomized trial that compared the effects of the drug alendronate (a widely used bisphosphonate) in more than 6,000 postmenopausal women with low bone mineral density, which is a risk factor for fractures.

The women's bone density was measured at the start of the study and again one, two and three years later. After three years of treatment, 97.5 percent of the women who took the drug showed at least a modest increase in bone density, and there was little variation in the treatment effect between individuals, the researchers found.

The findings, which appear online June 24 in BMJ, suggest that monitoring a person's response during the first three years of the treatment is unnecessary and, because of the potential to mislead, should not be done, concluded the researchers, from the School of Public Health at the University of Sydney.

The results support the case against routine monitoring during the early years of treatment, according to an accompanying editorial by Juliet Compston, professor of bone medicine at the University of Cambridge, in England. She said that when changes in bone mineral density are used to monitor treatment, people may be given inappropriate advice.

"Routine monitoring of bone mineral density during the first few years of antiresorptive treatment cannot be justified because it may mislead patients, lead to inappropriate management decisions and waste scarce health care resources," she concluded.

SOURCE: BMJ, news release, June 23, 2009