July 29, 2015
New Study Questions Link Between “Low T” Therapy,
Blood Clots

Galveston, TX—Last summer, the FDA added a general warning to the drug labeling on all approved testosterone products about the risk of venous thromboembolism (VTE), including deep vein thrombosis (DVT), and pulmonary embolism (PE).

The action was taken because of postmarket reports of venous blood clots in addition to those related to polycthemia, which already was addressed on the labels.

Now, however, a new study of more than 30,000 commercially insured men finds no link between testosterone therapy and blood clots in veins.

“Having filled a prescription for testosterone therapy was not associated with an increased risk of VTE in commercially insured middle-aged and older men. These findings may provide clinically relevant information about the benefit-risk assessment for men with testosterone deficiency considering treatment,” concludes the report, published by Mayo Clinic Proceedings. The research was conducted at The University of Texas Medical Branch at Galveston.

“In 2014, the Federal Drug Administration required manufacturers to add a warning about potential risks of VTE to the label of all approved testosterone products,” said lead author Jacques Baillargeon, PhD, professor of epidemiology in the department of preventive medicine and community health. “The warning, however, is based primarily on post-marketing drug surveillance and case reports. To date, there have been no published comparative, large-scale studies examining the association of testosterone therapy and the risk of VTE.”

For the case-control study, which included 30,572 men 40 years and older who were enrolled in one of the nation’s largest commercial insurance programs between January 1, 2007 and December 31, 2012, cases were defined as men who had a primary diagnosis of VTE and received an anticoagulant drug or an intravascular vena cava filter in the 60 days following their diagnoses. Cases were matched with three control subjects on age, geographic region, diagnosis of low testosterone, and diagnosis of any underlying pro-clotting condition.

Results indicate not only that having a prescription for testosterone therapy failed to increase risk of VTE, but also that none of the specific routes of administration examined—topical creams, transdermal patches or intramuscular injections—were individually associated with an increased risk. The study also detected no differences between men who received the therapy 15, 30, or 60 days before being diagnosed with VTE.

“It is important to acknowledge, for a man who has medically-diagnosed low testosterone, that there are clear risks to not receiving testosterone therapy, including osteoporosis, sexual dysfunction, increased amounts of fat tissue, decreased lean muscle mass, possible metabolic syndrome and cardiovascular disease,” said Baillargeon, who was quoted in a press release from The University of Texas Medical Branch at Galveston. “It's also important to note that further research needs to be conducted to rigorously assess the long-term risks of testosterone therapy.”

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