A study just published on bmj.com reports that rosiglitazone, a drug used to treat type 2 diabetes, is linked with an increased risk of heart failure and death among elder patients compared to pioglitazone, which is a similar drug.
As a result, the researchers point out it is questionable to support continued use of rosiglitazone for the majority of patients.
Rosiglitazone and pioglitazone are part of a group of drugs called thiazolidinediones. They are commonly used for the treatment of type 2 diabetes. They are useful in controlling blood sugar levels. However, both drugs can also cause side effects including weight gain, fluid retention and heart failure.
As nobody knew for certain whether there were any clinically significant differences in the cardiac safety of these two drugs, researchers in Canada compared the risk of heart attack, heart failure and death in patients treated with rosiglitazone and pioglitazone.
They identified about 40,000 patients aged 66 years and older, with the help of prescription records. They all had started treatment with either rosiglitazone or pioglitazone between April 2002 and March 2008.
Information on hospital admission for either a heart attack or heart failure during the six-year study period was recorded. Deaths were identified from a national database.
In depth examination indicated that patients treated with pioglitazone had a considerably lower risk of heart failure and death compared to patients treated with rosiglitazone. But, there was no important difference in the risk of heart attack.
The researchers calculate approximately that, for every 93 patients treated with rosiglitazone instead of pioglitazone, one extra cardiovascular event or death would be predicted to occur yearly.
“Our findings suggest clinically important differences in the cardiovascular safety profiles of rosiglitazone and pioglitazone in clinical practice,” explain the authors. “Given the accumulating evidence of harm with rosiglitazone treatment and the lack of a distinct clinical advantage for the drug over pioglitazone, it is reasonable to question whether ongoing use of rosiglitazone is justified,” they write in conclusion.
In an associated editorial, two experts from the Universities of Bath and Surrey comment that this study supports the suggestion that thiazolidinediones should be avoided in heart failure patients, but the claim that pioglitazone is safer than rosiglitazone is not entirely backed up by the information.
“Although it may be tempting to move away from prescribing thiazolidinedione altogether,” they write, “long term follow-up data for newer products are not yet available”.
Since randomized trials seldom reveal all the facts, they recommend that reinforcement to healthcare databases together with suitably planned studies (similar to this one) are fundamental for determining the complete risk-benefit outline of medicines. Patients with concerns about their diabetes treatment are encouraged to seek advice from their GP and not to suspend taking their medication.
“Adverse cardiovascular events during treatment with pioglitazone and rosiglitazone: population based cohort study”
David N Juurlink, division head, Tara Gomes, epidemiologist, Lorraine L Lipscombe, assistant professor, Peter C Austin, senior scientist, Janet E Hux, senior scientist, Muhammad M Mamdani, centre director
BMJ 2009; 339:b2942
« Rosiglitazone or pioglitazone in type 2 diabetes? »
Corinne S de Vries, professor of pharmacoepidemiology,David L Russell-Jones, professor of diabetes and endocrinology
doi=10.1136/bmj.b3076
bmj.com
Written by Stephanie Brunner (B.A.)