Pfizer ( PFE) on Monday disputed an allegation by a consumer group that the company hid and downplayed the results of a test of the arthritis drug Celebrex. The consumer group Public Citizen said the test results hadn't been disclosed, but Pfizer said the results were presented at a scientific conference in 2000 and submitted to the Food and Drug Administration in June 2001. The study, which was monitored by an independent group of safety experts, was never published in a medical journal. "Pfizer diligently monitors the safety of all its medicines and shares this information with regulatory agencies worldwide," the company said Monday. The group claimed that its analysis of the data showed "a significantly increased rate of serious cardiovascular adverse events" among patients taking Celebrex than patients receiving placebo. But Pfizer said the test showed that "definitive conclusions about cardiovascular risk cannot be drawn from this study." In this study, Pfizer noted that Celebrex patients experienced "more cardiovascular events than patients taking a placebo. However, Celebrex patients "were up to four times more likely to have key cardiovascular risk factors" vs. the placebo patients, thus impairing the findings. Public Citizen said its analysis of test data reaffirmed its belief that Celebrex should be banned. Last week, the consumer group asked the FDA to ban both Celebrex and Bextra, another Pfizer arthritis drug. The group reiterated its request in a Jan. 31 letter to the FDA, containing its comments about the Celebrex study. Both Celebrex and Bextra belong to the class of drugs called COX-2 inhibitors. That's the same drug class that contains Vioxx, the arthritis drug that Merck ( MRK) pulled from the market on Sept. 30 after a Merck-sponsored test showed patients that patients taking Vioxx for more than 18 months had a higher risk of cardiovascular problems than did patients receiving a placebo.