Testosterone prescriptions for older men in the United States have increased more than three-fold over the past decade despite the risks being poorly understood. Now, for the first time, a comprehensive new study shows testosterone therapy does not increase men's risk for heart attack. Remarkably, testosterone was linked with a decreased incidence of heart attack in high-risk patients.
The study, conducted by researchers at the University of Texas Medical Branch (UTMB) at Galveston, is the most extensive of its kind to date, utilizing de-identified information from more than 24,000 Medicare beneficiaries 66 years or older treated with testosterone for eight years. It appears in the Annals of Pharmacotherapy.
"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 Jacques Baillargeon, UTMB associate professor of Preventive Medicine and Community Health and lead author of the study. "This concern has increased in the last few years based on the results of a clinical trial and two observational studies," he said. "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."
In recent years, the testosterone therapy market has grown to $1.6 billion annually as men seek to supplement low testosterone counts with products that may increase muscle tone and sex drive. However, patients and doctors alike had difficulty determining whether the benefits of testosterone therapy outweighed the risks. Previous safety investigations presented conflicting findings. A few of these studies suggest testosterone is linked with increased risk of heart attack, although some critics have questioned the quality of these data. Doctors, researchers and government agencies all agree that more research into this issue is necessary.
TheFDA decided June 20 to expand labeling on testosterone products to include a general warning about the risk of blood clots in veins. The FDA and European Medicines Agency are also further examining the safety of these products. This newest FDA warning comes shortly after the announcement that testosterone treatment manufacturers Abbott Laboratories, AbbVie Inc., Eli Lilly and Company, Pfizer and Actavis are facing a consolidated multidistrict litigation in Federal Court based on claims that they hid the risks of using testosterone treatments.
This new UTMB study evaluated enrollment and claims Medicare data for a clinically and socioeconomically diverse national sample treated with testosterone from 1997-2005. Men of the same age, race, Medicaid eligibility, and health status who did not receive testosterone therapy were used as a control group for comparison.
The researchers conducted several detailed statistical analyses using 109 medical diagnoses, 22 procedures and an estimated cumulative dose of testosterone to compare the rate of heart attack incidence between men who received testosterone therapy relative to similar men who did not receive testosterone therapy.
The analyses revealed that testosterone therapy was not associated with an increased risk of heart attack. Further, testosterone users with a higher probability of cardiovascular problems had a lower rate of heart attacks in comparison to equivalent patients who did not receive testosterone therapy.
"This is an exceptionally well-done study containing rigorous analyses of a large number of patients," said Baillargeon. "We believe that our study, placed alongside existing studies, provides substantial evidence that testosterone therapy does not increase risk of heart attack among older men," he said. "However, the only way to know be absolutely certain on this is with a large clinical study where each patient is followed prospectively across decades."