GlaxoSmithKline's diabetes drug Avandia was no riskier to the heart than a rival, U.S. researchers said, a finding that contradicts earlier studies and adds new fodder to the roiling debate over the drug's safety.
The study of more than 36,000 diabetics, done by researchers at health insurer WellPoint, found the risks of death or having a heart attack, heart failure, or both were the same, about 4 percent, for patients taking either Avandia, known generically as rosiglitazone, or Takeda Pharmaceutical's Actos, known generically as pioglitazone.
"This study provides patients and their doctors with another source of information about rosiglitazone and pioglitazone as they determine the best therapy for diabetes patients," said Debra Wertz of HealthCore, Wellpoint's research arm. The findings were published in Circulation: Cardiovascular Quality and Outcomes.
Several studies have found that Avandia raises heart risks in diabetics, and the U.S. Food and Drug Administration is weighing whether the drug is too dangerous to stay on the market.
An advisory panel last month voted 20 to 12 that Avandia should still be sold in the United States, but many panelists called for more restrictions and warnings.
WellPoint researchers studied 36,628 patients who had submitted insurance claims to the company for either of the drugs between 2001 and 2005.
They compared the risk of heart attack, heart failure, and death for an average of 14 months of treatment, and for 18 months after treatment.
"Within the commercially insured population that we assessed, we did not see a difference between the two agents," Mark Cziraky, a vice president at HealthCore who contributed to the study, said in a telephone interview.
The WellPoint study differs sharply from a larger study done by David Graham and colleagues at the U.S. Food and Drug Administration and the U.S. Centers for Medicare and Medicaid Services, who found Avandia increased the risk of heart failure, stroke and death among patients insured by Medicare, which largely insures people over the age of 65.
The average age among patients in the WellPoint study was 54 and likely represents a younger population, Cziraky said.
And the WellPoint study looked at claims data between 2001 and 2005 — before any health warnings emerged — while the Graham study looked at patients starting treatment between 2006-2009 — during a period when the drug was under a cloud.
That may have affected the patients doctors chose to receive the drug, Cziraky said.
He said HealthCore was asked to do the study by its parent because of concerns over the drug's safety.
Lori McLaughlin, a spokeswoman for WellPoint, said such studies are combined with outside research to help determine which drugs are best for patients, and which ones should be covered by the insurer, and at what rate.
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