Femmes trans sous hormones : 4,5 fois plus de caillots et plus d'AVC que les hommes ; hommes trans : plus d'infarctus

Survenue d'événements cardiovasculaires aigus chez les personnes transgenres sous hormonothérapie

Études de cohorte & registres Hormones croisées

Authors: Nienke M. Nota, Chantal M. Wiepjes, Christel J.M. de Blok, Louis J.G. Gooren, Baudewijntje P.C. Kreukels, Martin den Heijer
Journal: Circulation
Year: 2019
Source: https://doi.org/10.1161/CIRCULATIONAHA.118.038584

Summary

This short report used records from the Amsterdam gender clinic, which treats most trans people in the Netherlands. It counted strokes, heart attacks and blood clots in nearly 3,900 people on cross-sex hormones over about 8 to 9 years, and compared them with expected rates in the general population. Trans women had about 4.5 to 5.5 times the expected rate of blood clots and about twice the expected rate of stroke, and more heart attacks than women (but not men). Trans men had more heart attacks than women but about the same as men. Blood-clot risk was lower, though still raised, in trans women who started after 2001, when an older estrogen was dropped. The long follow-up makes this useful, but the comparison is with outside population figures, smoking was not accounted for, and the trans men's results rest on few events.

Key findings

L'étude incluait 2 517 femmes trans et 1 358 hommes trans traités à la clinique du genre d'Amsterdam, suivis environ 9 et 8 ans en moyenne.
Les femmes trans ont eu 73 caillots sanguins dans les veines : 5,5 fois le taux attendu chez les femmes et 4,5 fois celui des hommes.
Les femmes trans ont eu 29 AVC (2,4 fois le taux des femmes, 1,8 fois celui des hommes) et 30 crises cardiaques (2,6 fois le taux des femmes ; pas plus élevé que chez les hommes).
Les hommes trans ont eu 11 crises cardiaques : 3,7 fois le taux attendu chez les femmes et le même que celui attendu chez les hommes.
Les hommes trans n'ont eu que 6 AVC et 2 caillots sanguins, sans différence nette avec les hommes ni avec les femmes.
L'exclusion des femmes trans ayant commencé avant 2001 (année où un ancien œstrogène, l'éthinylestradiol, a été remplacé) a fait baisser le taux de caillots sanguins à environ 3,9 fois celui des femmes et 3,4 fois celui des hommes ; les autres risques n'ont pas baissé.
43 à 46 % des personnes de l'étude fumaient, et cela n'a pas pu être pris en compte.

Conclusion

Considering the limitations, the authors conclude that the incidences of strokes and VTEs are higher in transwomen receiving hormone therapy than in both reference women and men, and that transwomen and transmen receiving hormone therapy are at higher risk of myocardial infarction than reference women. They urge physicians and transgender individuals to be aware of this increased cardiovascular risk and to reduce risk factors such as smoking.

Methodological limitations

Very short report: It was published as a two-page letter with few details, so how events were defined, who was left out and how results were checked are only briefly described.
Outside comparison only: Rates were compared with figures from separate Dutch and Norwegian population studies that found cases in different ways, not with a matched group of similar people.
Other risk factors ignored: The authors could not account for smoking (43–46% smoked) or life stresses, and weight, diabetes and other risk factors were not accounted for either.
Events may have been missed: Events were found by searching clinic files for doctors' letters. Events treated elsewhere and not reported back may have been missed, so true rates are probably higher.
Older drugs: Much of the follow-up involved older drugs (ethinylestradiol and high-dose cyproterone). Leaving out early starters lowered blood-clot risk, so the headline figure overstates risk on today's drugs, though risk was still raised.
Few events in trans men: Results rest on 6 strokes, 11 heart attacks and 2 blood clots, so the figures are very uncertain.
Some people left out: People who stopped hormones for long periods or switched between male and female hormones (such as some detransitioners) were excluded, as were 52 people with a past event.
Uneven follow-up: The typical person was followed for only about 4 to 6 years, much less than the average, so much of the data comes from a minority treated for a long time.
One clinic: Everyone was treated at one specialist centre, so results may not apply outside the Netherlands.

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Summary

Key findings

Conclusion