Doctors and critics doubt the accuracy of Avandia study

Results of a clinical study announced in New Orleans recently appeared to exonerate Avandia from long-held suspicions that the drug causes adverse cardiovascular events in patients undergoing treatment for diabetes 2. Many doctors and other critics, however, say that the study is flawed and remain unconvinced of the findings. Financial analysts believe the results will likely give GlaxoSmithKline’s one-time blockbuster drug a sales boost.

Researchers announced the results of the RECORD trial at the American Diabetes Association meeting in New Orleans. The study monitored 2,220 patients who received Avandia (rosiglitazone) as a supplement to metformin, normally the first-line drug in diabetes 2 treatment, or sulphonylurea. 2,227 other patients received a combination of metformin and sulphonylurea without Avandia.

GlaxoSmithKline said the findings confirmed that “cardiovascular hospitalization and cardiovascular death was not statistically different between the two groups after an average of 5.5 years of therapy.”

Philip Home, a professor at Newcastle University in Newcastle Upon Tyne in the UK and chairman of the RECORD trial, said the data “leads us to conclude that rosiglitaone carries no increased risk of overall cardiovascular death or hospitalization compared to the most commonly used diabetes medicines…which have been used for decades.”

However, an editorial by Toronto doctors Ravi Retnakaran and Bernard Zimman in the medical journal The Lancet, in which the RECORD results were published, raised doubts about the study’s accuracy. The doctors wrote that “definitive conclusions about the relation between rosiglitazone and cardiovascular disease remain elusive, owing to study limitations.”

The overall rate of cardiovascular problems in the RECORD patients was unusually low, and ten percent more of the Avandia patients were taking statins – cholesterol fighting drugs that effectively reduce the risk of heart attack.

Moreover, 45 percent of the RECORD participants dropped out of the study at some point, yet Glaxo maintains that the high dropout rate did not influence the results. Doctors Retnakaran and Zimman believe that dropout rate alone compromises the trial’s conclusions.

Steven E. Nissen, M.D. of the Cleveland Clinic said that “it is impossible to assess the safety of a drug when patients are not actually taking it.”