New debate over glitazone safety

TREATMENT with the thiazolidinedione, rosiglitazone, results in more deaths from any cause than does treatment with pioglitazone, a study of elderly patients with diabetes has confirmed.

However, an Australian expert said the latest findings did not provide further clarity on the safety of each agent.

A cohort study of more than 28,000 US patients older than 65 years, with type 2 diabetes, found those using rosiglitazone had a 15% greater rate of all-cause mortality and a 13% greater incidence of hospitalisation than those using pioglitazone.

The rosiglitazone group also had a 13% higher risk of congestive heart failure. There were, however, no differences between the rates of myocardial infarction or stroke in either group.

Associate Professor Duncan Topliss, director of endocrinology and diabetes at Melbourne’s Alfred Health, said: “You would have to say that it doesn’t provide any reassurance about the safety of rosiglitazone, but I don’t think I would conclude from this that now we know that [rosiglitazone] is more dangerous [than pioglitazone].”

He said caution was needed in interpreting the latest data because the study was non-randomised.

Guidelines issued by the American Diabetes Association and the European Association for the Study of Diabetes this year recommended that rosiglitazone not be used for type 2 diabetes, following studies showing its use led to an increase in ischaemic cardiovascular events.

In Australia, the TGA added a black box warning to rosiglitazone late last year. Despite this, experts had previously commented it was unlikely that NHMRC guidelines would change to advise against its use.

A spokesperson for GlaxoSmithKline, manufacturers of rosiglitazone (Avandia), said the study didn’t add anything to the “debate about the heart safety of Avandia”.

“Final long-term data from ongoing cardiovascular outcome studies such as RECORD should be available within a year,” the spokesperson said.

Arch Intern Med 2008; 168(21): 2368-2375.