Findings Run Counter to Earlier Research

A study of 24,000 Medicare patients found that testosterone therapy didn't increase the risk of heart attack, contrary to several earlier studies, and that it even lowered the risk of heart attack by about 30% in the group of men judged most likely to have one based on other factors.

The findings are a boost for proponents of testosterone therapy, but still aren't likely to settle the long-standing debate over testosterone safety any time soon.

Sales of testosterone products have tripled in the last decade, to over $2 billion in 2012, and manufacturers such as Eli Lilly have spent millions advertising the benefits of restoring "low T," including boosting sexual function and muscle tone.

Separately, a new book revealed that Major League Baseball gave New York Yankees slugger Alex Rodriguez a rare exemption to use testosterone therapy in 2007 due to an "androgen deficiency." Mr. Rodriquez, then 31 years old, hit a league-leading 54 home runs with 156 runs batted in that season. He has been suspended for the 2014 season for allegedly using performance-enhancing drugs.

Mr. Rodriguez's spokesman, Ron Berkowitz, issued a statement saying, "We have no comment. We have turned the page from this and are looking toward 2015 and getting back on the field."

Several studies have linked testosterone use to higher cardiovascular risks in older men. Last year, a study in the Journal of the American Medical Association reported that testosterone raised the risk of death, heart attack and stroke by about 30% in veterans with a history of heart disease.

But critics have attacked the study's methodology for, among other things, including over 100 women among the 1,132 subjects studied. Over 25 international medical groups have demanded that JAMA retract the article. JAMA has declined to do so.

In the latest study, published online in the Annals of Pharmacotherapy, researchers at the University of Texas Medical Branch used a national Medicare sample and compared the records of 6,355 men who had at least one testosterone injection between 1997 and 2005, with 19,065 non-testosterone users. The testosterone users were no more likely to have a myocardial infarction than the nonusers during the period, according to the study.

The researchers also ranked the subjects based on their predicted risk of heart attack for other reasons. For men in the quarter with the highest risk, the use of testosterone cut that risk by roughly 30% .

"Our study brings some balance to the discussion and I think it has far-reaching clinical and public-health implications," said lead researcher Jacques Baillargeon, director of epidemiology at the University of Texas Medical Branch.

The latest study had several limitations, the authors noted. It looked only at men receiving testosterone injections, not those using pills, patches or gels, and couldn't assess what other medications the men were taking. Those using testosterone therapy could be more likely to take drugs that lowered their heart-attack risks, or to exercise and watch their diets.

Men typically lose testosterone as they age, and some conditions can cause a steep drop in levels earlier, leading to osteoporosis, sexual dysfunction, loss of muscle tone, fatigue, diabetes and other health problems. Proponents say restoring normal levels can alleviate those issues, but debate has raged over what level is considered "low" in older men