The study, led by Dr. Mahyar Etminan from the University of British Columbia, is the third largest epidemiological study to signal potential harm among the millions of users of testosterone patches, gels, creams and injections.
The Canadian study (“Testosterone Therapy and Risk of Myocardial Infarction: A Pharmacoepidemiologic Study,” Pharmacotherapy, November 2014) looked at the records of close to one million men from the IMS LifeLInk Health Plan Claims Database, which included the largest-ever number of cases of heart attack with TRT exposure.
“This study did not find an association between myocardial infarction (MI) and current use; however, it did find a statistically significant association between first-time TRT exposure and MI, although the risk was very low,” notes Dr. Etminan.
Study authors report that they found 515 cases of MI who were new users of TRT. The mostly commonly used method of use among that group was the gel, but all formulations showed higher risks for men with pre-existing cardiovascular disease.
Etminan is quick to point out that studies have “limitations” and that “adverse drug reactions are usually highest with first-time users.” However, the authors write that although the results are not a complete match to previous studies, they do “raise a potential MI safety signal among first-time TRT-exposed men.”
Given the higher incidence of MI in this group with pre-established cardiovascular disease, this “safety signal is potentially most concerning in this group,” the authors write.
And finally, Etminan’s group adds that given the safety risks and the absence of established benefit for off-label use, TRT should be reserved for men with “clinically and biochemically proven hypogonadism.”
However, the use of TRT has tripled between 2001 and 2011 and sales of TRT products are now approaching $2 billion annually. The exact risks and benefits are still not completely understood and the Etminan study is an important contribution to the conversation.
On March 3, 2015, the FDA issued an updated safety announcement on the use of testosterone replacement therapies. It cautioned that testosterone should be prescribed only for medical conditions confirmed by laboratory tests and not for decreased hormone levels due to the aging process.
The FDA wrote in its safety announcement that “We are requiring that the manufacturers of all approved prescription testosterone products change their labeling to clarify the approved uses of these medications. We are also requiring these manufacturers to add information to the labeling about a possible increased risk of heart attacks and strokes in patients taking testosterone.”
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Etminan’s study was the first to look at the risks in new users of TRT. There are still many questions to be answered about the use of testosterone replacement therapy and Etminan believes more clinical trials are necessary to complete the picture.
Mahyar Etminan, PharmD, MSc is a scientist with the Pharmaceutical Outcomes Programme and is an assistant professor in the Department of Medicine at the University of British Columbia in Canada, and the author of many major research studies.