MONTHLY BIPHOSPHONATE THE SAME AS WEEKLY

Monthly Ibandronate as Effective as Weekly Risedronate or Alendronate

Alison Palkhivala

Medscape Medical News 2008. © 2008 Medscape

September 17, 2008 (Montreal, Quebec) � Monthly ibandronate therapy is as effective in the prevention of fractures as weekly therapy with risedronate or alendronate in a real-world setting, according to posters presented on September 14 and 15 here at the American Society for Bone and Mineral Research (ASBMR) 30th Annual Meeting.

"It's been our feeling all along that there are some patients who would prefer to take once-a-month therapy rather than once-a-week therapy, particularly if you look at [the administration regimen] of these compounds, where you have to take them on an empty stomach with plain water and wait," Steven T. Harris MD, FACP, clinical professor of medicine at the University of California at San Francisco, told Medscape Medical News. He is lead author of the first poster and senior author of the second. According to his research, "people don't have to apologize if they prefer to take a monthly dose [of bisphosphonate] because they're not sacrificing efficacy for convenience."

"Medication fatigue" associated with long-term bisphosphonate therapy is a common problem that can be at least partly remedied with once monthly-therapy, Robert Recker, MD, professor of medicine at Creighton University School of Medicine, in Omaha, Neraska, told Medscape Medical News. He attended the ASBMR conference but was not involved in this research. "It's hard to get people to take bisphosphonates for months and years when success means nothing happens. . . . People comply much better with a once-a-month therapy than a once-a-week therapy," he said, although he acknowledged that adherence to medication is tough to track.

For the Evaluation of Ibandronate Efficacy (VIBE) study, the researchers used medical-claims databases to identify 7345 women, 45 years or older, who were newly prescribed once-monthly ibandronate 150 mg and 56,837 prescribed once-weekly alendronate (35 mg or 70 mg) or risedronate (35 mg) between April and December 2005. The participants had been adherent to their therapy for at least 90 days and did not have cancer or Paget's disease. The researchers used regression analysis to compare fracture rates between the 2 groups, after adjustment for potential confounding factors. Mean follow-up was approximately 7 months.

The risk for hip fracture, nonvertebral facture, and all fracture was similar in both groups, with an all-fracture rate of 1.5% with weekly bisphosphonate therapy and 1.4% with monthly ibandronate. Interestingly, vertebral fracture rates were actually a little bit lower with monthly ibandronate (0.11% vs 0.24%; P = .006).

"The intent of this particular analysis is to do a whole bunch of sensitivity analyses, so that if you take out this subgroup of patients, or you take out that subgroup of patients, are findings the same? And the answer is yes," said Dr. Harris. Sensitivity analyses involved excluding patients taking estrogen, calcitonin, or raloxifene; patients taking glucocorticoids; patients who experienced a fracture; patients taking gastrointestinal medication; and patients on glucocorticoids and/or with osteopenia and/or on alendronate during the preindex period. None of these exclusions significantly affected the results.

A subanalysis presented in a separate poster involved only women 65 years or older. "There's been a concern that maybe among older patients efficacy might be different than among the younger prevention population," said Dr. Harris. "When you restrict your analysis to the over-65 group, you're enriching your population of osteoporotic patients, as opposed to patients who might be osteopenic or something of the sort." Once again, the findings were similar.

"It looks like the fracture rates for patients getting monthly [ibandronate] were very comparable to those of patients getting weekly [risedronate or alendronate]," said Dr. Harris. "If anything, interestingly, there's a little bit of a trend favoring a reduction of vertebral fractures for patients who got monthly [ibandronate]."

"It's good that [once-a-month ibandronate] is effective in all these types of patients," said Dr. Recker, "and it's not hugely unexpected. [These data] provide confirmation and reassurance."