A clinical trial that used testosterone gel, a topically applied ointment, to increase muscle strength in older men with low testosterone levels was stopped because adverse cardiovascular events increased significantly among patients receiving the treatment.
The Testosterone in Older Men study at Boston Medical Center, funded by the National Institute on Aging, was testing 209 men, averaging 74 years of age, to see if testosterone gel would improve their muscle strength and mobility.
Previous studies of the gel’s effects had been done on older men who had normal testosterone levels for their age. This was the first time a study focused on men with low levels of the hormone. The 209 patients in this study, many with existing diabetic and heart conditions, were divided into two groups: The first group, comprising 106 men, received a prescribed dose of the gel over a six-month period. The second group, numbering 103, received a placebo.
The study was halted when its Data and Safety Monitoring Board noted that 23 of the 106 men receiving the gel had experienced what they called “adverse cardiovascular events,” compared to only five of the men in the placebo group. The adverse events included elevated blood pressure, problems with heart rhythm, and heart attack, including one suspected death from the latter. The research team is continuing to monitor participants for one year after cessation of the treatment to see if there will be long-term effects.
The Boston Medical Center study, which was reported in the June 30 online edition of the New England Journal of Medicine, was one of six NIA-funded studies nationwide that are looking into the effects of testosterone gel on various physiological functions in men.
In men with pre-diabetes or type 2 diabetes, low testosterone levels are common. Studies that have been done on men with diabetes and metabolic syndrome have shown that topically applied testosterone gel reduces insulin resistance-although not as well as other diabetes medications-and increases the ability to get and sustain erections. However, those studies involved a range of ages, which is why observers of the Boston trial have cautioned against assuming too much on the basis of its preliminary results. They point to the participants’ advanced average age, the small size of the study group, and the fact that many patients already had major health problems.
Still, it was the great difference between the number of cardiovascular events among the gel-taking group compared to the placebo group that caused greatest concern. The NIA has told researchers conducting other studies involving testosterone treatment to pay close attention to the Boston results.