Merck last week said it made an error when reporting in early 2005 that a statistical test showed Vioxx caused heart problems only after 18 months of continuous use. The 18-month theory was based data from a test known as the Approve study, in which Merck tracked 2,600 patients to see whether Vioxx could help prevent colon polyps. When the Approve study results were reported in The New England Journal of Medicine in March 2005 they stated that Vioxx posed significantly higher cardiovascular risk than placebo only after 18 months and no extra risk before that time. Peter Kim, Merck’s chief scientist, said in a report in The New York Times that Merck found its mistake only last week told the FDA and non-Merck researchers who had taken part in the Approve study. “We came forth quickly to let the study authors know about the error, let the regulatory agencies know about the error,” Kim said in The Times report.