Earlier data inconclusive
Testosterone concentrations progressively decline in men with advancing age, at about 2% per year, Dr. Michos and Dr. Budoff write. In addition, men with obesity or with diabetes have low levels of testosterone, Dr. Michos noted.
Low testosterone blood levels have been associated with insulin resistance, inflammation, dyslipidemia, and atherosclerosis. Testosterone replacement therapy has been used to increase libido, improve erectile dysfunction, and boost energy levels, mood, and muscle strength.
But it is well known that testosterone increases hematocrit, which has the potential to increase the risk of venous thromboembolism.
Two large observational studies have reported increased risks of myocardial infarction, stroke, and death in men taking testosterone, compared with nonusers, but the study designs have been widely criticized, Dr. Hudson and coauthors say in their article.
A placebo-controlled trial was stopped early by its data- and safety-monitoring board following increased cardiovascular events in men aged 65 and older who received 6 months of testosterone. Other controlled trials have not observed these effects, but none was sufficiently powered.
Meta-analysis results
Dr. Hudson and colleagues performed a meta-analysis of 35 trials in 5,601 men aged 18 years and older with low baseline testosterone (≤ 350 nmol/dL) who had been randomized to testosterone replacement therapy or placebo for at least 3 months, for which there were data on mortality, stroke, and cardiovascular outcomes.
The men were a mean age of 65, had a mean body mass index of 30 kg/m2, and most (88%) were White. A quarter had angina, 8% had a previous myocardial infarction, and 27% had diabetes.
Cardiovascular and cerebrovascular outcomes were not primary outcomes.
During a mean follow-up of 9.5 months, in the 13 trials that provided this information, the rate of cardiovascular events was similar in the men who received testosterone (120/1,601, 7.5%) compared with those who received placebo (110/1,519, 7.2%).
In the 14 trials that provided this information, fewer deaths were reported during testosterone treatment (6/1,621, 0.4%) than during placebo treatment (12/1,537, 0.8%), but these numbers were too small to establish whether testosterone reduced mortality risk.
The most common cardiovascular events were arrhythmia, followed by coronary heart disease, heart failure, and myocardial infarction.
Patient age, baseline testosterone, smoking status, or diabetes status were not associated with cardiovascular risk.
The only detected adverse effects were edema and a modest lowering of HDL cholesterol.
“Men who develop sexual dysfunction, unexplained anemia, or osteoporosis should be tested for low testosterone,” senior author of the meta-analysis Dr. Jayasena said in an email to this news organization.
However, Dr. Jayasena added, “Mass screening for testosterone has no benefit in asymptomatic men.”
“Older men may still benefit from testosterone, but only if they have the clinical features [of hypogonadism] and low testosterone levels,” he concluded.
The current study is supported by the Health Technology Assessment program of the National Institute for Health Research. The TRAVERSE trial is sponsored by AbbVie. Dr. Jayasena has reported receiving research grants from LogixX Pharma. Dr. Hudson has reported no relevant financial relationships. Disclosures for the other authors are listed in the article. Dr. Michos has reported receiving support from the Amato Fund in Women’s Cardiovascular Health at Johns Hopkins School of Medicine and serving on medical advisory boards for Novartis, Esperion, Amarin, and AstraZeneca outside the submitted work. Dr. Budoff has reported receiving grant support from General Electric.
A version of this article first appeared on Medscape.com.