(Adds company comments, paragraphs 13-14)
By Julie Steenhuysen
CHICAGO Oct 13 A long-term analysis of people who took the arthritis drug Vioxx confirms it doubles the risk of strokes and heart attacks, researchers said on Monday, but this risk goes away a year after people stop taking it.
And other drugs in the same class of painkillers known as Cox-2 inhibitors may cause similar harm, they 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," said Dr. Robert Bresalier of the M.D. Anderson Cancer Center at the University of Texas, whose study appears in the journal Lancet.
Safety data from this same study in 2004 set off alarms that Vioxx increased the risks of heart attacks and stroke, prompting drug maker Merck & Co Inc (MRK.N) to withdraw the popular painkiller from the market.
Merck last year inked a $4.85 billion deal to settle thousands of claims for heart attacks, strokes and deaths allegedly caused by the drug. The original study, funded by Merck, was meant to determine whether Vioxx could prevent polyps that raise the risk of colon cancer.
A 2005 analysis by Bresalier and colleagues published in the New England Journal of Medicine suggested that it took 18 months for the drug to increase the risk of heart attacks and strokes, a time frame that played a prominent role in Merck's legal defense of Vioxx.
The journal later posted a correction on its Web site, saying the difference was not statistically significant. The new analysis, done with independent statisticians, suggests the risk occurs early and persists, Bresalier said.
"This data shows you can't precisely determine the timing of the risk. It does appear to start relatively early," he said in a telephone interview.
The study, dubbed Approve, looked at the effects of three years of treatment with Vioxx, or rofecoxib, in 2,587 patients. Patients were checked for side effects while on the drug and two weeks after they stopped.
It includes one-year follow-up data on patients who stopped taking the drug because of heart side effects.
"In essence, the relative risk remained about the same," Bresalier said.
MERCK CALLS DATA LIMITED
People who took Vioxx in the study had about the double the risk of having a heart attack or stroke than those who took a dummy pill, he said.
Merck said that overall findings were consistent with the original study, but noted not all patients were able to be followed after they stopped taking the drug and the analysis was not able to take into account other heart risks.
The company said in a statement it believes that 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."
Bresalier said a number of studies since the initial safety warning on Vioxx suggest other Cox-2 inhibitors, including Pfizer Inc's (PFE.N) Celebrex, or celecoxib, and non-steroidal anti-inflammatory drugs (NSAIDS) such as ibuprofen, also carry a higher risk of heart trouble.
"I think the preponderance of data now does suggest this is a class effect," he said.
Cox-2 drugs were designed to be safer replacements for NSAIDS, including aspirin and naproxen, which can cause deadly gastrointestinal bleeding.
"There seems to be an increased risk for most if not all non-steroidal anti-inflammatory drugs. That doesn't mean these aren't good drugs. It's just there is some increased risk we need to be aware of," he said.
Vioxx had generated sales of $2.5 billion a year before the arthritis and chronic pain pill was withdrawn from U.S. drugstores almost four years ago. Pfizer's Celebrex has remained on the market.
(Editing by Will Dunham and Cynthia Osterman)