Nissen was the first scientist to publish concerns about Avandia and increased heart risks in a study last May.
After that and other research was released, the FDA added a "black box" warning to all drugs in the class. An FDA advisory panel voted against removing the drug from the market, citing inconclusive evidence.
The Canadian label for Avandia carries a stronger message: The drug is not to be used as the sole medication for type 2 diabetes unless the patient cannot take another drug to lower blood sugar and that the drug should not be used by any patient with heart failure.
People with type 2 diabetes are already at heightened risk for cardiovascular disease.
Thiazolidinediones including Avandia and Actos (pioglitazone) heighten the body's sensitivity to insulin. Some 3.5 million U.S. patients take Avandia, which has also been linked to bone loss in some patients.
The current study involved an older (66 and over), "real-world" population consisting of more than 159,000 residents of Ontario in this age group who were treated with at least one oral diabetic medication. The patients were followed for about four years.
Compared to individuals taking more than one oral hypoglycemic agent, people using Avandia on its own had a 60 percent increased risk of congestive heart failure, a 40 percent increased risk of heart attack, and a 29 percent increased risk of dying.
The increased risks were associated with Avandia only, but fewer people in the study took Actos, so the results could be skewed, the researchers noted.
"It looks like the results were limited to Avandia, but 50 percent fewer people were on Actos, so you can't rule out an increased or decreased risk with Actos," Lipscombe said. "We need more studies."
"It's an observational study and, like all observational studies, this has strengths and weaknesses. These studies
All rights reserved