More MIs in men 90 days after starting testosterone therapy, study finds

Receiving a prescription for testosterone therapy was associated with increased risk of myocardial infarction (MI) in the next 90 days, a recent study found.

The cohort study included more than 50,000 men who had an initial testosterone therapy (TT) prescription between January 2008 and October 2010. Researchers compared the incidence rate of non-fatal MI among these men in the year prior to the prescription and the 90 days following the prescription. They did the same comparison in more than 150,000 men prescribed phosphodiesterase type 5 inhibitors (PDE5I). Results were published by PLOS One on Jan. 29.

Overall, the rate ratio (RR) of MI 90 days after a TT prescription compared to the year before was 1.36 (95% CI, 1.03 to 1.81) in the men studied, while there was no significant change with PDE5I prescriptions. In men age 65 and over, the rate ratio was 2.19 (95% CI, 1.27 to 3.77) with TT, with, again, no significant difference in MI rates before and after a PDE5I prescription. The MI risk associated with TT increased with age, from 0.95 for men under age 55 (95% CI, 0.54 to 1.67) to 3.43 for men 75 or older (95% CI, 1.54 to 7.56). PDE5Is showed no such trend. Men under 65 only had an increased risk for MI with a TT prescription if they had a history of heart disease, but the risk ratio for these patients was particularly high: 2.90 (95% CI, 1.49 to 5.62).

In older men and younger ones with heart disease, initiation of a TT prescription was associated with a substantial increase in MI risk, the study authors concluded. This finding is consistent with other recent research and supports an association between TT and risk of serious cardiovascular events, the authors said. Possible explanations include that exogenous testosterone has different effects from endogenous testosterone and that the circulating estrogens increased by TT may have an effect.

More trials are urgently needed to assess the benefits and risks of TT, including the impact of different doses, duration and pre-existing conditions in patients, the study authors said. In the meantime, however, “clinicians might be well advised to include serious cardiovascular events in their discussions with patients of potential risks, particularly for men with existing cardiovascular disease.”

In response to the publication of this study and other recent research, the FDA announced that it is investigating the risk of stroke, heart attack and death in men taking FDA-approved testosterone products. While this investigation is ongoing, clinicians should consider whether the benefits of TT are likely to exceed potential risks, the agency advised.