WASHINGTON (Reuters) - Early results from an ongoing study of GlaxoSmithKline Plc's Avandia was unable to show any increase in heart attacks among patients, but several experts said the evidence still suggests the popular diabetes drug raises the risk of heart attack.
The interim analysis of the study, funded by the drugmaker and published in the New England Journal of Medicine on Tuesday, did show twice as many patients taking the drug had congestive heart failure, researchers said.
That congestive heart failure issue is already well known, Glaxo said separately.
Last month Dr. Steven Nissen of the Cleveland Clinic in Ohio created a stir when he published a study in the same journal suggesting the drug raised the risk of heart attacks by 43 percent.
Nissen's was a meta-analysis -- a pooled analysis of data from several trials.
How the company and U.S. health officials communicated Avandia's risks to doctors and patients will be the subject of a U.S. House of Representatives committee hearing on Wednesday.
Philip Horne of Britain's Newcastle University and a team from around the world looked at the ongoing study of 4,400 patients to see if they could find any evidence that patients taking Avandia, known generically as rosiglitazone, were more likely to have a heart attack.
Glaxo and three independent heart experts had sharply different views on what the results of the study meant.
"Patients and physicians should find these data reassuring," Moncef Slaoui, Glaxo's research and development chairman, said in a statement.
But Dr. Bruce Psaty of the University of Washington in Seattle, and Dr. Curt Furberg of Wake Forest University, said all the trials studied so far, pooled with this one, suggest a 33 percent higher risk of heart attack.
"Rosiglitazone ... appears to be associated with an increase rather than a decrease in the risk of myocardial infarction (heart attack)," they wrote in a commentary.
Glaxo disputes Nissen's conclusion and, along with the U.S. Food and Drug Administration, says other studies offer conflicting results.
Most experts agree the continuing trial, called Rosiglitazone Evaluated for Cardiac Outcomes and Regulation of glycemia in Diabetes, or Record for short, should provide a more authoritative answer.
Tuesday's report was a analysis of the interim results of Record, which is only halfway finished and which was not specifically designed to detect an increased rate of heart attack.
NO DIFFERENCES:
"There were no statistically significant differences between the rosiglitazone group and the control group regarding (heart attack) and death from cardiovascular cause or any cause," Horne's team wrote.
"The data were insufficient to determine whether the drug was associated with an increase in the risk of (heart attack)," they added.
"Because the mean follow-up was only 3.75 years, our interim analysis had limited statistical power to detect treatment differences." A final analysis is not expected until the trial concludes in 2009.
Psaty and Furberg also noted that Avandia is associated with a risk of weight gain, raises low density lipoprotein or "bad" cholesterol levels as well as fractures.
They said all the patients in the Record study had a suspiciously low number of heart attacks, given that they had a mean age of 60, had long-standing diabetes and a quarter already had cardiovascular disease. The rate in both the Avandia and control groups was about 40 percent of what would have normally been expected, they said in a commentary.
Dr. David Nathan, a diabetes expert at Massachusetts General Hospital and Harvard Medical School, said the low rate of heart problems and other issues made the data hard to interpret.
"The interim results of the Record trial do not provide any assurance of the safety of treatment with rosiglitazone," Nathan wrote in a second commentary.
Shares of Glaxo briefly rose as much as 3.5 percent, or $1.80, after the release of the analysis but gave up nearly all their gains to close up just 9 cents at $51.90 on the New York Stock Exchange. Glaxo shares had traded around $57 prior to the release of Nissen's study in May.
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