Avandia Study Spurs New Heart Risk Debate
Diabetes Drug Doesn't Raise Risk of Death From Heart Disease, Shows Study; Critics Find Flaws
"But what we do know is that this is not associated with cardiovascular death," he said. "There were actually fewer deaths in the [Avandia] group."
In the study, all patients received standard treatment with metformin and/or a sulfonylurea. Half added Avandia to this treatment. The study was not blinded, meaning that study investigators and patients knew which treatment they were getting.
Nissen doubts that this unblinded study will convince experts to change their minds about Avandia. That, he says, will happen only if a new study -- the just-started TIDE study -- shows Avandia is truly safe. The TIDE study is a double-blind trial. And even though it is sponsored by GlaxoSmithKline, there will be a direct comparison of Avandia to Actos, made by Takeda Pharmaceuticals.
Home disagrees, and expects the American Diabetes Association committee to give serious consideration to the new findings, which appear in the June 5 early online edition of The Lancet.
In an editorial accompanying the study, Ravi Retnakaran and Bernard Zinman of Toronto's Mt. Sinai Hospital agree with Nissen that the study's open-label design -- and it's much lower-than-expected rate of cardiovascular deaths -- are problematic.
"Definitive conclusions about the relation between [Avandia] and cardiovascular risk remain elusive, owing to study limitations," Retnakaran and Zinman write. "Furthermore, the findings are inconclusive for [heart attack], for which a non-statistically-significant increased risk was noted in the [Avandia] group."
Unfortunately, a definitive answer isn't soon forthcoming. The TIDE trial isn't scheduled to end until October 2015.
Meanwhile, Retnakaran and Zinman suggest that doctors consider prescribing half doses of Avandia, noting that a half dose offers more than half the benefit of a full dose -- and fewer risks.