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23
May
2007

Avandia and Heart Attacks

Effect of Rosiglitazone on the Risk of Myocardial Infarction and Death from Cardiovascular Causes. NEJM 5/21/07; 356

Avandia (generic name rosiglitazone) is a thiazolidinedione medication for type II diabetes. It is an agonist for peroxisome-proliferator-activated receptor gamma (PPAR-gamma) and has been around since 1999.

In diabetics, 65% of deaths are cardiovascular related. The meta-analysis of this study was done to increase the power to see what are the cardiovascular outcomes.

116 studies were investigated and 42 studies were analyzed for this meta-analysis. Criteria for entry included more than 24 weeks of drug exposure, randomized studies, MI (heart attack) or cardiovascular deaths had to be reported. Outcomes: MI. Cardiovascular Deaths.

15,560 people were in the Avandia treatment group and 12,283 in the control group (control group were divided into those taking insulin, sulfonylurea, metformin, and placebo). Most of the subjects were men around 57 years old, and diabetes control was relatively poor in both groups (HbA1C average 8.2%)

The trials had very few MIs or cardiovascular deaths, so they used some statistical method I have never heard of, the Peto Method. I’m not sure how they determined what would be clinically significant and statistically significant between Avandia group and control group.

Results are pretty similar. In the Avandia group, there were 86 MIs (0.55%) and in the Control group 72 MIs (0.58%). For cardiovascular deaths, the Avandia group had 39 deaths (0.25%) and the Control group had 22 deaths (0.18%).

So for MIs, Avandia had a 1.43 times increased risk of MI compared to control (43%) that is statistically significant. But in epidemiology, 43% increase risk is a weak to mild association. You need more of a 200-300% increase risk to be a strong association. Also if you just look at the numbers, 86 heart attacks out of 15,560 isn’t a whole lot in particular vs. 72 heart attacks out of 12,283 controls.

For cardiovascular, there is no increased risk of cardiovascular death that is statistically proven.

I think the findings are interesting but it is too soon to “jump the gun” like the media is doing. A study needs to be done and powered correctly to see if Avandia does indeed cause heart attacks and/or cardiovascular deaths. But I don’t think anyone can say for sure at this point that Avandia does cause heart attacks. We do know Avandia can’t be used in Stage III or IV congestive heart failure and I wonder if the heart attacks were due to this. Many questions have been raised from this meta-analysis.

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