It must feel like Groundhog Day for GlaxoSmithKline as another analysis has been revealed which claims that Avandia, as well as Takeda’s Actos, is associated with an increased risk of congestive heart failure, heart attack and death compared with other oral diabetes drugs in older patients.

The respective analysis, which has been published in the Journal of the American Medical Association, involved over 159,000 diabetes patients in Canada aged 66 years or older who were treated with at least one oral hypoglycaemic agent between 2002 and 2005 and were followed up until March 31, 2006. It concludes that treatment with the thiazolidinedione class, which includes Avandia (rosiglitazone) and Takeda's Actos (pioglitazone), led to a 60% percent increased risk of heart failure, a 40% rise in the risk of heart attacks and a 30% increased risk of death, compared with patients taking other oral diabetes medicines.

“Our study suggests that, at least in this high-risk population, the harms of the drug may outweigh the benefits,” said the study’s lead author, Lorraine Lipscombe of the non-profit Institute for Clinical Evaluative Sciences in Toronto. The study data suggests that Avandia increased the risks more than Actos, though the authors noted that this could be just because fewer patients were prescribed Takeda’s treatment.

The study comes to the same conclusions as the controversial meta-analysis published in May in the New England Journal of Medicine which claimed that use of Avandia increased cardiovascular risks. The latter led to the Food and Drug Administration last month adding information to Avandia's black box warning about potential increased heart attack risk, though the agency voted unanimously to keep the drug on the market.

The FDA has responded to the Canada analysis saying that the new study does not change its recommendations on Avandia. The agency added that the information it provided for the most recent labelling change remains accurate, as “the data are inconclusive”.

GSK claimed that the ICES analysis “has significant limitations and generates misleading conclusions regarding acute myocardial infarction and death”. The firm said that the conclusions “are inconsistent with a more robust body of evidence from large, long-term, prospective, well-designed clinical studies, including ADOPT and RECORD”, adding that the authors of the retrospective analysis “fail to acknowledge the findings of large epidemiological studies, encompassing over 1.3 million patients with type 2 diabetes”.

The majority of these studies show that “rosiglitazone is not associated with an increased risk of myocardial infarction compared to other anti-diabetic agents”, GSK concluded.