It is too soon to write off GlaxoSmithKline’s Avandia for type-2 diabetes, according to a new report by two US cardiologists.

Avandia (rosiglitazone) came under fire after an article published online by the New England Journal of Medicine in May suggested the drug significantly increased users’ risk of serious heart disease. The NEJM study was a large meta-analysis of 42 clinical trials involving 27,847 patients receiving Avandia.

But according to Dr George Diamond and Dr Sanjay Kaul of the Cedars-Sinai Medical Center in Los Angeles, re-analysis of the data suggests that the earlier methodology may have exaggerated the risk posed by the drug. The cardiologists claim that an alternative method of checking the drug’s safety found no statistically significant increase in the risk of heart attack or cardiovascular death.

The original study used data from wide-ranging clinical trials that were not necessarily designed to track heart attacks and cardiovascular death. In addition, most of the trials did not report occurrence of any heart attack or cardiovascular death. In this type of "sparse data" situation, it is claimed that the statistical model employed by the NEJM researchers may have over-estimated the risk. When the "corrected" data were recomputed using a different model, risk estimates were found to be lower.

"Although the risks were still elevated, they were no longer statistically significant. There was greater uncertainty about the risk associated with Avandia than was originally reported, with neither increased nor decreased risk established conclusively," the authors say.

"The original meta-analysis employed one statistical model, but there are other approaches that deserve consideration as well. Only when different methods give us the same answers should we be confident in the results," Dr Diamond noted. In their report they conclude: "that only prospective clinical trials designed for the specific purpose of establishing the cardiovascular benefit or risk of Avandia will resolve the controversy about its safety."

Both cardiologists testified on July 30, before a Food and Drug Administration advisory committee reviewing the data on Avandia's safety. At the conclusion of hearings, the panel recommended that Avandia carry new risk warnings but stopped short of calling for the drug to be removed from the market. By Michael Day