Staff | Sun Herald

Q: My husband takes Avandia for his Type 2 diabetes. I'm beside myself with worry after hearing that this drug increases the risk of heart attacks. Should he stop taking it?

A: These latest findings on Avandia (rosiglitazone) are cause for concern but not alarm.

The FDA has not advised doctors to stop prescribing Avandia, and patients should not stop taking it without consulting their doctors.

Rosiglitazone is also found in Avandaryl and Avandamet, which combine it with another diabetes drug.

The latest study was a meta-analysis of 42 prior studies. Researchers reported a 43 percent increased risk of heart attack associated with Avandia compared to a placebo (fake pill).

Experts have pointed out a number of possible flaws in the new analysis, and some prior clinical trials have found no higher risk of heart attack for Avandia than for other diabetes drugs.

However, another meta-analysis provided by Avandia's manufacturer suggested a 30 percent higher risk of heart attack with Avandia compared to a placebo.

More will be known at the conclusion of a current large clinical trial involving Avandia and other diabetes drugs that's expected to be finished in late 2008.

In short, the information is blurry at this point, and the FDA is trying to clarify the Avandia picture.

Readers might find it helpful to know the difference between the two types of risks reported in clinical studies.

The 43 percent higher risk of heart attack associated with Avandia is relative risk, which can make risk seem deceptively high. Looking at absolute risk adds perspective.

Here's a related hypothetical example: A clinical trial consisted of 1,000 participants, with 500 taking a drug pill and the other 500 taking a fake pill (placebo). Myocardial infarction (heart attack) occurred in 6 of those on the drug and in 4 of those on placebo.

This means the drug group had an absolute risk of 1.2 percent (6 divided by 500) and the placebo group had an absolute risk of 0.8 percent (4 divided by 500). The difference between the two (0.4 percent or less than half of one percent) is the actual risk of heart attack associated with the drug.

The relative risk is the difference between the two absolute risks (0.4 percent) divided by the placebo absolute risk (0.8 percent), which comes to 0.5 or 50 percent. Thus, those on the drug had a 50 percent increased risk of heart attack compared to those on placebo.

A 50 percent increased risk (relative risk) for heart attack warrants serious concern. But it does not mean that you have a 50 percent chance of having a heart attack (the chance is less than half of 1 percent as explained above).

The popular media's penchant for reporting only relative risk can be unnecessarily alarming.

Unfortunately, the absolute risk for Avandia in the latest meta-analysis cannot be accurately determined. However, the reported numbers suggest that this risk is small.

A joint statement issued by the American Diabetes Association, American College of Cardiology and American Heart Association said that "As estimated here, the overall level of the risk associated with rosiglitazone (Avandia) appears to be small, but nonetheless one that must be considered carefully."

As with any prescription drug, you and your doctor should decide whether the benefits outweigh the risks.