Drugmaker Merck withdrew its painkiller Vioxx from the market in 2004 after a study showed the drug increased patients' risk of heart attacks and strokes. An estimated 20 million Americans had taken the painkiller.
Now, new data reveal the drug is riskier than thought. NPR Health Editor Joe Neel answers questions about the latest news on the painkiller Vioxx and its health risks:
Q: I thought the risks of Vioxx only increased if you took it for longer than 18 months. Has that changed?
Yes. Documents obtained by NPR show that in a three-year study of Vioxx, the risk of heart attacks, strokes and serious peripheral vascular disorders began to increase soon after people started taking 25 mg of Vioxx each day. The documents do not provide precise data on when the risk actually starts.
How big is the risk?
That's difficult to answer because Merck & Co., Vioxx's maker, has not released all of the data that were collected in the study, known by its acronym APPROVe (Adenomatous Polyp PRevention on Vioxx). But the charts and tables that have been reviewed by NPR and several experts show that people who took Vioxx for less than 18 months did have more heart attacks, strokes and other cardiovascular problems than those taking a placebo.
This represents a change from an earlier report on the APPROVe trial, published in the New England Journal of Medicine last year. In that report, the risk of cardiovascular problems did not begin to rise until people had taken Vioxx for more than an year and a half.
What is Merck's response?
Merck disagrees with this interpretation. The company has long said there's no evidence that Vioxx caused problems after relatively short-term use. Spokesmen for the company say the published APPROVe data show that a definite increase in cardiovascular problems only occurs in patients who took Vioxx longer than 18 months.
Merck says that the new data obtained by NPR doesn't change its original interpretation. In a written statement to NPR, the company said that "the new APPROVe data do not establish that the risk for VIOXX starts earlier than had previously been reported.''
What should I do if I took Vioxx for a shorter period?
There are no official recommendations on what to do. You should consult your doctor for the best advice. Dr. Steven Nissen of the Cleveland Clinic told NPR that he's telling his older patients to be sure they're taking a baby aspirin a day to lower the risk of a heart attack. As more is known about the data in the APPROVe study, these recommendations could change.
I was taking 50 mg a day, what is my risk?
The APPROVe study only studied the lower 25 mg dose. It's not possible at this point to say whether the risk is higher or lower at that dosage.
I stopped taking Vioxx a long time ago. Do I need to be worried?
Cardiologists and clinical study experts consulted by NPR say that yes, those who took Vioxx and their doctors should be concerned. The reason is that the new APPROVe data show that people still have a substantial risk of cardiovascular problems for at least a year after they've stopped Vioxx, and this effect may persist longer.
Merck disputes this interpretation of the data, as well. In a press release, the company pointed out that the number of heart problems once patients had stopped taking Vioxx was so small that it's not clear whether Vioxx caused the problems. In scientific terms, the company said that even though the trend was toward more problems with Vioxx, the difference between those who took Vioxx and those who took placebo was not statistically significant after Vioxx was stopped.
What kinds of cardiovascular problems are we talking about?
There are several dozen specific kinds of problems that have been identified, including serious strokes, so-called "ministrokes" (also known as transient ischemic attacks), heart attacks, angina, congestive heart failure, coronary artery disease, phlebitis and other serious blockages of veins. Over the three years of the study when people took Vioxx and for a year after, there were 28 deaths among the 1,287 people taking Vioxx, versus 16 among the 1,300 who received a placebo.