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Avandia News
New Study Questions Avandia's Heart Risk
WEDNESDAY, Aug. 8 (HealthDay News) -- The debate over the heart-attack risks posed by the type 2 diabetes drug Avandia has taken another twist, with a new study questioning the results of the research that kick-started the controversy.
In a study published June 14 in the New England Journal of Medicine, heart expert Dr. Steven E. Nissen, chairman of the Cleveland Clinic's department of cardiovascular medicine, reported a 43 percent increased risk of heart attack among patients taking Avandia (generic name rosiglitazone). Nissen said he uncovered that risk among 42 studies of the drug that he had analyzed.
However, a new analysis of that same data finds no proof of a significant risk of heart attack.
"We don't have sufficient data to adjudicate the association of rosiglitazone with increased cardiovascular risk," said lead researcher Dr. Sanjay Kaul, a cardiologist and professor of medicine at the University of California, Los Angeles. "The data that was analyzed does not allow us to conclude definitively whether the risk of heart attack with rosiglitazone is increased or decreased."
Kaul, who published his findings online Aug. 7 in Annals of Internal Medicine, and his colleagues reexamined the same trials that Nissen had used in his study. Kaul said he found that Nissen's analysis excluded trials that should have been included -- trials that would have lowered the risk of heart attack because none occurred.
In addition, Kaul said, those trials weren't designed to assess the safety of Avandia, and they were too short to establish whether there was a long-term risk for heart attack. "The number of events was very small," Kaul said. "One can legitimately raise the question whether you can predict long-term outcomes looking at short-term clinical trials."
To really answer the question about the potential heart risks associated with Avandia, there needs to be long-term trials specifically designed to see if the drug increases the chances of heart attack, Kaul said.
In response to Nissen's study, the U.S. Food and Drug Administration convened an expert panel in July to consider the heart-attack risk associated with Avandia. The panel recommended that the drug be kept on the market, but that a warning be attached that there may be an increased risk of heart attack. Avandia has already been linked to an increased risk of heart failure. The FDA has requested that Avandia's maker, GlaxoSmithKline, strengthen its warning about heart-failure risk.
Kaul said he agreed with the advisory panel's decision. "Because of the uncertainty, you can't pull a drug off the market. You have to be absolutely certain that there is substantial risk associated with it," he said.
GlaxoSmithKline said it stands behind the drug. "Across the extensive dataset for Avandia, GlaxoSmithKline believes there is no consistent or systematic evidence that Avandia increases the risk of heart attack or cardiovascular death in comparison to other anti-diabetic medicines," the company said in a prepared statement.
Nissen, for his part, said that a more detailed analysis by the FDA that was used by the advisory panel during its deliberations has confirmed the risk of heart attack with Avandia. This more thorough FDA research has left his original study "no longer relevant," he said.
"The FDA presented a more statistically powerful patient-level analysis at the advisory board meeting on rosiglitazone (Avandia)," he said. "This is a far more accurate approach when you have access to patient data, which we did not. The FDA confirmed a 40 percent increase in risk, virtually identical to our findings reported in the New England Journal of Medicine. Further study-level analysis will not yield any important insights," he added.
Kaul, however, disagreed with Nissen that the FDA's analysis confirmed a risk of heart attack from Avandia. According to Kaul, the FDA study looked at both serious and non-serious heart-related events.
"There was not a statistically significant difference between serious and non-serious events, which is exactly what we found," Kaul said. "There was substantial uncertainty associated with those risk estimates. You couldn't say one way or the other whether the risk was increased or decreased. When they looked at myocardial infarction [heart attack], they did not find a statistically significant increased risk," he added.
Kaul agreed that there is a heart-attack risk with Avandia, but the size of the risk is uncertain. "It's no longer statistically significant when you look at myocardial infarction," he said. "But, if tomorrow there is evidence to suggest increased risk, we will be the first ones to acknowledge it."
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