Patients receiving hormone therapy as part of their gender-transition treatment have an elevated risk of cardiovascular diseases (CVD), including heart attacks, strokes and blood clotting, researchers say.

Researchers determined and compared the incidence of CVD cases in the transgender population with that reported in the general population. The study showed that transwomen -- individuals, assigned male sex at birth but with female gender identity, receiving hormones as part of their transition -- had more than twice as many strokes as women and nearly twice as many strokes as men.

In addition, there were five times as many blood clotting among transwomen than women and 4.5 times more than men. Heart attacks occurred at more than twice the rate among transwomen than women. On the other hand, transmen -- those assigned female sex at birth but had male gender identity and received hormones -- had a more than three-fold rise in heart-attack risk compared with women, said the study, published in the journal, Circulation.

"In the light of our results, we urge both physicians and transgender individuals to be aware of this increased cardiovascular risk," said Nienke Nota, researcher at the Amsterdam University Medical Center in the Netherlands. "It may be helpful to reduce the risk factors by stopping smoking, exercising, eating a healthy diet and losing weight, if needed before starting therapy, and clinicians should continue to evaluate patients on an ongoing basis thereafter," suggested Nota.

For the study, the researchers included 3,875 individuals who had received hormone treatment -- 2,517 transgender women received estrogen, with or without androgen-suppressors, and 1,358 transgender men received testosterone -- as part of their transition.