Diabetes Drug Avandia Boosts Heart Risks: Study

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For the first study, Singh and his colleagues conducted a meta-analysis of four randomized trials of Avandia involving more than 14,000 patients.

In the analysis, Avandia increased the risk of heart attack by 42 percent and doubled the risk of heart failure, similar to findings of a previous study. In this analysis, Avandia did not increase the risk of death from cardiovascular causes, however.

The study received no funding from GlaxoSmithKline, the maker of Avandia.

With an estimated 3.5 million or more U.S. patients taking Avandia, the public health impact could be substantial, the authors point out. This could translate into more than 4,000 excess heart attacks and 9,000 excess heart failure events.

For the second study, also a meta-analysis, Lincoff and his colleagues looked at data from 19 trials involving more than 16,000 participants that looked at Actos and cardiovascular complications.

According to the study authors, Actos' manufacturer, Takeda Pharma, funded the analysis and provided the data from the trials but was not involved in any of the analysis.

Like Avandia, Actos also raised users' risk for heart failure, this time by about 40 percent.

However, unlike Avandia, patients receiving Actos had an 18 percent lower risk of heart attack, stroke or death than patients in the control group.

Why might two drugs in the same class have different effects? "For this type of drug, a 'class' is a really loose term, because the medications have very different actions on multiple targets," Lincoff said. Actos should probably be the first-line choice, over Avandia, he said.

Not surprisingly, Avandia's maker GlaxoSmithKline disputed that conclusion.

The two JAMA studies do not bring any new data forward and "do not confirm a difference in the safety profile of Avandia and Actos," the company said in a statement released late Tuesday.

According to the company, the Actos analysis, in particular, relied heavily on one trial -- the Takeda-funded PROactive study -- which only compared Actos to a placebo. "Patients taking Actos to control blood sugar might be expected to have fewer cardiovascular events than those who were not controlled on medication," the company noted.

GlaxoSmithKline also pointed out that, at this point in time, "no long-term, head-to-head clinical trial data specifically evaluates cardiovascular risk between Avandia and Actos."

Dehmer agreed, saying that more trials, namely randomized trials looking at specifically at cardiovascular outcomes, are needed to fully assess the effects of the two drugs.

More information

For more on diabetes drugs, visit the U.S. Food and Drug Administration.