The researchers note that they can't tell yet if there is an association between Avandia and heart attacks or Avandia and heart disease in general. However, the researchers report an association between Avandia and heart failure, with more than twice as many heart failure cases in patients taking Avandia vs. other types of diabetes drugs.
In June, the FDA announced that Avandia and another diabetes drug, Actos, will soon carry a "black box" warning about heart failure risk. An editorial published with the study urges patients not to stop taking Avandia on their own, but to talk with their doctor about Avandia's risks and benefits.
The Avandia-heart risk debate hit the headlines in May, when other researchers suggested that Avandia might increase the risk of heart attack and death due to heart disease. Avandia' maker, GlaxoSmithKline, has called those findings flawed.
Today's journal report comes from the interim results of a six-year Avandia study sponsored by GlaxoSmithKline. The interim results cover the study's first 3.75 years. The data include 4,447 patients with type 2 diabetes in Europe and Australia who couldn't adequately control their blood sugar with the diabetes drugs metformin or sulfonylurea.
Half of the patients took Avandia and a combination of metformin and sulfonylurea. For comparison, the other patients took the metformin-sulfonylurea drug combination without Avandia. The patients were 58 years old, on average. Apart from their diabetes, they were generally in good health.
The researchers included Philip Home, DM, DPhil, of England's Newcastle Diabetes Centre and Newcastle University. They tracked the patients' hospitalization or death from any cardiovascular problems.
The study shows no increased risk of heart attack or heart problems in general in patients taking Avandia, compared with those not taking Avandia. However, heart failure was 2.15 times more common in the Avandia group.
But there are three other points to consider.
First, the time span was relatively short. Second, the researchers couldn't track down 10% of the patients for follow-up. Third, relatively few patients died or were hospitalized for cardiovascular problems.
Those limitations make it hard to form definite conclusions from the study's interim data. "The final report will be more extensive," write the researchers.
The study is accompanied by three editorials on Avandia and heart risks. All three editorials conclude that uncertainty remains about Avandia's effects on heart health.
"When it comes to patient safety, 'first, do no harm' should outweigh any presumption of innocence," writes editorialist David Nathan, M.D., of Harvard Medical School and the Diabetes Center at Massachusetts General Hospital in Boston.
In the journal, Nathan notes financial ties to drug companies Pfizer, GlaxoSmithKline, Novartis, Novo Nordisk, and Sanofi-Aventis.
Another editorial suggests weighing the pros and cons of Avandia in treating type 2 diabetes.
"Together, patients and physicians can decide whether they wish to suspend the use of rosiglitazone [Avandia's active ingredient]," states that editorial, written by doctors including Bruce Psaty, M.D., Ph.D., of the University of Washington's cardiovascular health research unit.
Psaty's team notes no potential conflicts of interest in the journal.
By Miranda Hitti
Reviewed by Louise Chang, M.D.
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