Merck's Vioxx Under Fire Again

A study published in the New England Journal of Medicine suggests that Vioxx heightens the risk of cardiovascular problems faster than Merck (MRK) says it does.

The study, which contains several caveats, raises questions about Merck's assertion that cardiovascular risks were statistically significant only after patients took the arthritis drug for more than 18 months. Several critics have challenged Merck's conclusions about Vioxx, which was removed from the market in September 2004.

Vioxx therapy "was associated with an increased frequency of adverse cardiovascular events among patients with a median treatment of 7.4 months' duration," says the article, published Wednesday online by NEJM. The article uses data from a Merck-sponsored study that was halted after the company withdrew Vioxx.

The article was prepared by researchers at several British medical schools and a U.K. hospital. Their work was sponsored by Oxford University and an education grant from Merck.

When Merck withdrew Vioxx, it acted on results of another company-funded clinical trial, which assessed if Vioxx could reduce certain colon polyps. The trial was known by the acronym APPROVE. Merck said an independent safety monitoring board recommended stopping APPROVE due to higher risks of cardiovascular problems in patients who took Vioxx for more than 18 months.

Authors of the NEJM article used data from a study called VICTOR, which was checking if Vioxx could reduce the recurrence of colon cancer. Researchers point out that their work was hampered by "the small number of events available for analysis" and the 7.4-month median exposure to Vioxx.

"However, our findings suggest an increased risk" of dangerous cardiovascular side effects for Vioxx patients compared with placebo recipients, they say. There was no significant difference in heart-related deaths between the groups.