Researchers analyzed records from more than 25,000 Medicare beneficiaries and found no evidence that testosterone replacement therapy increases the risk of heart attack among older men.
A study that analyzed records from 25,420 Medicare beneficiaries concluded that testosterone replacement therapy does not increase the risk of heart attack among older men.
The study, which appears in the July 2 issue of Annals of Pharmacotherapy, directly contradicts another large analysis that appeared earlier this year in PLoS One and helped spur an investigation of testosterone therapies by the US Food and Drug Administration (FDA).
The new study, which was funded by the U.S. National Institutes of Health, started with a 5% sample of Medicare beneficiaries nationwide and identified 6,355 who had been treated with at least 1 injection of testosterone between January 1, 1997 and December 31, 2005.
Researchers then compared that group to 19,065 people who did not use testosterone but had otherwise similar risks of myocardial infarction (MI). All patients were followed until they experienced MI, died or stopped using Medicare. The end of study date was December 31, 2005, so researchers traced patients anywhere from a few days to eight years.
A Cox regression analysis that adjusted for demographic and clinical characteristics found no association between the receipt of testosterone therapy and an increased risk of MI (hazard ratio [HR] = 0.84; 95% CI = 0.69-1.02).
To the contrary, for men in the highest quartile of the MI prognostic score, testosterone therapy was associated with a reduced risk of MI (HR = 0.69; 95% CI = 0.53-0.92).
There was no difference in risk for the first (HR = 1.20; 95% CI = 0.88-1.67), second (HR = 0.94; 95% CI = 0.69-1.30), and third quartiles (HR = 0.78; 95% CI = 0.59-1.01).
“Our investigation was motivated by a growing concern, in the U.S. and internationally, that testosterone therapy increases men's risk for cardiovascular disease, specifically heart attack and stroke,” said lead author Jacques Baillargeon, PhD, in a news release that accompanied publication of the study.
“This concern has increased in the last few years based on the results of a clinical trial and two observational studies,” continued Baillargeon, an associate professor of epidemiology at the University of Texas Medical Branch in Galveston. “It is important to note, however, that there is a large body of evidence that is consistent with our finding of no increased risk of heart attack associated with testosterone use.”
The PLoS One study looked at the medical records of 56,000 men for the 90 days after they began taking testosterone replacement therapy and found that heart attack risk doubled in men over 65 and in younger men with a history of heart disease. The analysis did not find any increased risk of heart disease among men who were under 65 and had no history of heart disease.
The FDA decided to conduct its own investigation into the possible cardiovascular risks of testosterone replacement therapy after the publication of the PLoS One study and a highly controversial study that was published late last year in the Journal of the American Medical Association, a study that found testosterone increased both the risk of stroke and heart disease in all users.
The agency also decided, just last month, to order the maker of such products to reword their labels to warn users about an increased risk of venous clots.