Two more meta-analyses, or studies that review the results of multiple past clinical trials, have found that taking the diabetes drug rosiglitazone (brand name Avandia) appears to increase heart attack risk while its rival drug, pioglitazone (Actos) does not. The studies confirmed, however, that both drugs increase the risk of heart failure.
The studies, both published online September 12 in The Journal of the American Medical Association (JAMA), looked at the two members of the thiazolidinedione class of diabetes drugs. These drugs help people with Type 2 diabetes control their blood glucose levels by making the body’s tissues more sensitive to insulin. Earlier this year, the U.S. Food and Drug Administration (FDA) required that both drugs carry a “black box” warning, the strongest type required, about raising the risk of heart failure. (For more information, see the blog entry “New Data on Avandia; New Warnings for TZD Drugs.”) Also, in May of this year, a meta-analysis published in The New England Journal of Medicine found that people who took rosiglitazone had a 43% increased risk of having a heart attack. (See “Type 2 Drug Avandia Linked to Increased Risk of Heart Attacks.”)
While the meta-analysis published in NEJM in May looked at more than 40 studies that each lasted a minimum of 24 weeks, the meta-analysis looking at rosiglitazone that was published this week in JAMA narrowed its focus to only four large studies that lasted at least a year. In total, these four studies involved more than 14,000 participants. Conducted by researchers from Wake Forest University School of Medicine, the analysis showed that people who took rosiglitazone had a 42% increased risk of heart attack and double the risk of heart failure compared to those who took other diabetes drugs or a placebo. In absolute numbers, 94 out of 6,421 or 1.46% of people taking rosiglitazone had a heart attack, whereas 83 out of 7,870 or 1.05% of people in a control group had a heart attack. The study also found that while it increased heart attack and heart failure rates, rosiglitazone did not increase people’s risk of death from cardiovascular causes.
The other meta-analysis published in JAMA this week, performed by researchers from the Cleveland Clinic, looked at 19 studies of pioglitazone and cardiovascular health that involved more than 16,000 participants. It found that, like rosiglitazone, pioglitazone increased participants’ risk of heart failure, though by a lower rate of 40%. However, the people who took pioglitazone in the studies also had an 18% lower risk of heart attack, stroke, or death than those who took another diabetes drug or a placebo. These results imply that pioglitazone may actually have some protective effects on the heart. This study was funded by pioglitazone’s manufacturer, Takeda Pharmaceutical Company.
Pioglitazone is currently outselling rosiglitazone two to one, whereas earlier this year their sales numbers were very similar. However, as one of the authors of the Wake Forest study commented, there are also older and less expensive diabetes drugs in other classes that may be better choices for many people with diabetes.
The FDA is continuing to assess the safety of rosiglitazone to decide whether any further action is needed to protect the public. If you have any concerns about prescription drugs you take, make sure to discuss them with your doctor before making any decisions.