WEDNESDAY, Nov. 17 (HealthDay News) -- Using the controversial
diabetes drug Avandia as an example, new research finds that
doctors' prescribing patterns vary across the country in response
to warnings about medications from the U.S. Food and Drug
The result is that patients may be exposed to different levels
of risk depending on where they live, the researchers said.
"We were looking at the impact black-box warnings for drugs have at a national level, and, more specifically, at a geographical level, and how these warnings are incorporated into practice," said study lead researcher Nilay D. Shah, an assistant professor of health services research at the Mayo Clinic in Rochester, Minn.
In 2007, the FDA required that Avandia come with a "black-box
warning" -- the strongest warning possible -- alerting consumers
that the drug was associated with an increased risk of heart
Before the warning, Avandia was widely prescribed throughout the
United States, although regional differences existed. "There was
about a two-fold difference in use before the warning -- around
15.5 percent use in Oklahoma versus about 8 percent in North
Dakota," Shah said.
Right after the warning, the use of Avandia dropped
dramatically, from a nationwide high of 1.3 million monthly
prescriptions in January 2007 to roughly 317,000 monthly
prescriptions in June 2009.
"There was a huge decrease in use across the country," Shah said. "But there was quite a bit of residual use."
After the FDA warning, the researchers still found as much as a
three-fold difference in use across the nation. In Oklahoma,
Avandia use dropped to about 5.6 percent, but in North Dakota it
tumbled to 1.9 percent, Shah said.
The reasons for the differences aren't clear. Some factors might
include how doctors are made aware of FDA warnings and how they
react. Another factor could be the policy of state health insurance
plans, including Medicaid, in terms of covering drugs, he said.
Also, prominent doctors in given areas can influence the choice
of drugs other doctors make, Shah said. And drug-company marketing
may play a role, he said.
"At this point we don't have good insight into these differences," he said.
This problem isn't unique to Avandia, Shah said. "This is not
uncommon with a lot of drugs," he said. "This is a good case
The report was published in the Nov. 17 edition of the
New England Journal of Medicine.
The study also found that the American Diabetes Association's
January 2009 consensus statement advising against prescribing
Avandia appeared to have had a "negligible influence" on trends in
The study authors think the FDA could do a better job of
alerting all doctors about warning labels. "The FDA could provide a
tool for doctors and patients to show the risks and benefits of
going on the drug," Shah said.
As for Avandia, in September the FDA introduced further
restrictions on use of the drug. The agency is requiring Avandia's
maker, GlaxoSmithKline, to develop a program that will limit access
to the drug to patients for whom other treatments have not
Also, doctors will have to state and document a patient's
eligibility to use Avandia. They will also have to tell patients
about the cardiovascular safety risks associated with Avandia, and
patients will have to acknowledge that they understand those
Commenting on the new study, Dr. Luigi Meneghini, professor and
director of clinical operations in the division of endocrinology,
diabetes and metabolism at the University of Miami Miller School of
Medicine, said "there was still some confusion about the negative
effects of Avandia."
"Physicians tend to be skeptical and not change their habits unless there is solid evidence, and with Avandia the evidence was not as solid as one would want," he said. "But, for the majority of physicians there was clearly a change in the way they prescribe."
With the new restrictions the FDA has placed on Avandia,
Meneghini believes that very few doctors will be prescribing the
Meneghini added that the FDA is pretty good at getting warning
information out to doctors. "Whether the warning is heeded depends
on the availability of the drug, the importance of the drug and
patient desires," he said.
Also, many doctors stopped prescribing Avandia when the warning
came out due to fear of liability, Meneghini said. "That drove a
lot of the decisions," he said.
For more on Avandia, visit the
U.S. National Library of Medicine.