FDA Will Review Safety of Testosterone Therapy
Agency pointed to recent studies citing possible heightened heart risk tied to the treatments
The study was conducted by a research team that included experts from Consolidated Research, the U.S. National Cancer Institute and the University of California, Los Angeles.
It was prompted by a 2010 report in the New England Journal of Medicine, Finkle said. In that study, a clinical trial of testosterone gel in men over 65 was halted early after an increase in heart attacks and other heart problems occurred in the group using the testosterone treatment.
Finkle's team used data from Truven Health Analytics, which gathers nationwide information on patient care. The researchers looked at the medical records of nearly 56,000 men who had been prescribed testosterone therapy -- more than 48,000 of whom were under age 65.
"We identified the [timing of the] first prescription and followed them for 90 days," Finkle said. The risk for heart attack doubled in that 90-day period for men over 65 and those under 65 with a history of heart disease, the researchers found.
When they continued to follow the men for another 90 days, the researchers said, the risk declined to the level it was at the study's start for men who did not refill their initial prescription.
Even though the two-fold increase in risk in younger men was seen only in those with a history of heart disease, Finkle said he's uncertain of the therapy's safety in younger, healthy men.
"We don't have enough evidence to say testosterone supplements in men under age 65 without heart disease are safe," he said.
Although the researchers found an association between testosterone therapy and increased risk of heart attack, the study did not prove a cause-and-effect relationship.
The study authors also did not examine the explanation for the link, but Finkle said it could be tied to the effect of testosterone in blood.
"The theory is that testosterone most likely promotes clotting," he said. In older men who tend to have thinner vessels, that clotting could cause problems, he said.
The supplements might also increase men's circulating estrogen, the researchers said. Estrogen therapy has been linked to an increase in heart troubles in both men and women.