Study Finds New Risks for Avandia

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A new study of an older, "real-world" population, published in the December 12 issue of The Journal of the American Medical Association (JAMA), has confirmed the findings of earlier research by linking Type 2 diabetes drug rosiglitazone (brand name Avandia) with increased heart risks. It has also uncovered a new risk associated with the drug—namely, an increased risk of dying that had not been observed before. Studies of rosiglitazone have made the news a lot lately (see our own recent coverage in "Avandia: New Warning and Findings").

In the new study, researchers examined medical records for more than 159,000 people, aged 66 and over, living in Ontario, Canada. The records covered a four-year period, during which all of the people studied took at least one oral diabetes drug.

When they were compared to people who were taking combinations of other diabetes drugs, people who took rosiglitazone on its own had a 60% increased risk of congestive heart failure, a 40% increased risk of heart attack, and a 29% increased risk of dying.

While other studies have associated rosiglitazone with an increased risk of heart attack and both thiazolidinedione drugs (rosiglitazone and pioglitazone [Actos]) with an increased risk of congestive heart failure, this was the first study to link rosiglitazone with an increase in mortality rates.

While the new study did not link pioglitazone with the same increase in risks, 50% fewer people examined in the study took pioglitazone than rosiglitazone, which the researchers say could have skewed the results. They have called for further studies of both drugs in the thiazolidinedione class.

It is important to note that observational studies such as this one do not provide the same quality of evidence as randomized, controlled clinical trials. While randomized clinical trials carefully select participants and randomly assign them to receive different treatments, this new study is a bit different in that it was observational and population-based, meaning that its participants made their own treatment choices in real life and data about them was examined after the fact. The new study also focused on an older group of people than most clinical trials usually feature.

Rosiglitazone’s manufacturer, GlaxoSmithKline, responded to the study by stating that the research “has significant limitations” and pointing out that its “conclusions are inconsistent with a more robust body of evidence from large, long-term, prospective, well-designed clinical studies.” However, Steven Nissen, M.D., lead author of the first analysis to raise questions about rosiglitazone’s heart safety (see “Type 2 Drug Linked to Increased Risk of Heart Attacks”), pointed out that the large size of this new study and the fact that it was conducted independently, without sponsorship from any drug company, count in its favor.

When it comes to using rosiglitazone, “in older people, the risks may outweigh the benefit,” said lead study author Lorraine L. Lipscombe, M.D., M.Sc. By providing a “snapshot” of the drug’s apparent effects in a real-world setting, this new study will likely help keep the debate going about whether rosiglitazone is a safe treatment option for various groups of people with Type 2 diabetes.

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