After a long-term analysis of people who took Vioxx, researchers found that the arthritis drug doubled risk of heart attack, stroke and death persisted at least a year after people stopped taking the painkiller.

The study, published by the British medical journal The Lancet, also showes the higher risk started soon after patients began taking Vioxx, though the study notes a small sample size precludes a definitive finding on this issue. The study also notes that in the same class of painkillers known as Cox-2 inhibitors which could result in similar harm.

Dr. Robert Bresalier of the M.D. Anderson Cancer Center at the University of Texas said, "The good news is the data suggests that the risk doesn't persist forever. The risk goes back toward normal after a year of follow up."

Drug maker Merck & Co Inc. withdrew the painkiller from the market when safety data from the 2004 study showed an increased risk of heart attacks and stroke in users. The company then went on to spend $4.85 billion to settle lawsuits for claims of heart attacks, strokes and deaths allegedly caused by the drug. A 2005 study by Bresalier and colleagues published in the New England Journal of Medicine said that it took 18 months for the drug to increase the risk of heart attacks and strokes. A correction was later posted on the journal’s Web site, saying the difference was not statistically significant. "This data shows you can't precisely determine the timing of the risk. It does appear to start relatively early," Bresalier said in a telephone interview. "In essence, the relative risk remained about the same," he added.

Doug Watson, a cardiovascular epidemiologist and senior director at Merck Research Labs said the research "using limited data from a prematurely terminated study needs to be interpreted very cautiously and in the context of the rest of the data from the extensive clinical development program for Vioxx."

Celebrex, made by Pfizer Inc. is the only drug from the same class as Vioxx still on the market in the United States.