A new study has added to mounting evidence that rosiglitazone, a drug used to treat type 2 diabetes, is associated with an increased risk of major heart problems.
It finds that rosiglitazone is associated with significantly
higher odds of congestive heart failure, heart attack and death compared with a
similar drug (pioglitazone).
Rosiglitazone and pioglitazone belong to a class of drugs
called thiazolidinediones that help to control blood sugar levels in patients
with type 2 diabetes. Both drugs are known to increase the risk of heart
failure, but it is unclear whether there are clinically important differences
in their cardiac safety.
In 2010, the European Medicines Agency suspended the use of
rosiglitazone in Europe, but in the United States it is still available
on a restricted basis.
So a team of researchers in the UK
and the US
set out to compare the cardiovascular effects of the two drugs among patients
with type 2 diabetes.
They analysed the results of 16 studies involving 810,000
patients (429,000 on rosiglitazone and 381,000 on pioglitazone). Most patients were
aged over 60 years.
Compared with pioglitazone, rosiglitazone was associated
with a modest but statistically significant increased risk of heart attack
(16%), congestive heart failure (23%), and mortality (14%).
In certain groups of patients with type 2 diabetes, this may
lead to 170 excess heart attacks, 649 excess cases of heart failure, and 431
excess deaths for every 100,000 patients who receive rosiglitazone rather than
Further adjusting the data to minimise bias, did not change
the results significantly, suggesting that this is unlikely to be a chance
finding, say the authors.
"Our findings have important implications," they write.
"Rosiglitazone is still available on a restricted basis in the United States and Canada. However, for patients who
need thiazolidinedione treatment, continued use of rosiglitazone may lead to
excess heart attacks, heart failure and mortality, compared with pioglitazone."
Given that there are about 3.8 million prescriptions for
rosiglitazone dispensed annually in the United States, "the effect on
public health may be considerable," they warn.
They also emphasise that both rosiglitazone and pioglitazone
have been linked with other important safety concerns, and say that further
studies are needed.
In an accompanying editorial, Victor Montori and Nilay Shah
from the Mayo Clinic in the US
argue that the rosiglitazone story "says much about how healthcare has become
less about promoting patients' interests, alleviating illness, promoting
function and independence, and curing disease, and much more about promoting
other interests, including those of the drug industry."
They believe that regulators, prescribers, and
patients all have a role in promoting patient safety and they urge patients to
become engaged in decisions about their diabetes treatment.