Transvrouwen op hormonen: 4,5 keer zoveel bloedstolsels en meer beroertes dan mannen; transmannen meer hartaanvallen

Optreden van acute cardiovasculaire gebeurtenissen bij transgenders die hormoontherapie krijgen

Cohort- & registerstudies Cross-sekse hormonen

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

De studie omvatte 2.517 transvrouwen en 1.358 transmannen die bij de genderkliniek in Amsterdam werden behandeld, gemiddeld ongeveer 9 en 8 jaar gevolgd.
Transvrouwen hadden 73 bloedstolsels in aderen: 5,5 keer het verwachte cijfer bij vrouwen en 4,5 keer dat bij mannen.
Transvrouwen hadden 29 beroertes (2,4 keer het cijfer bij vrouwen, 1,8 keer dat bij mannen) en 30 hartaanvallen (2,6 keer het cijfer bij vrouwen; niet hoger dan bij mannen).
Transmannen hadden 11 hartaanvallen: 3,7 keer het verwachte cijfer bij vrouwen en gelijk aan het verwachte cijfer bij mannen.
Transmannen hadden slechts 6 beroertes en 2 bloedstolsels, zonder duidelijk verschil met mannen of vrouwen.
Transvrouwen weglaten die vóór 2001 begonnen (toen een oudere oestrogeen, ethinylestradiol, werd vervangen) verlaagde het cijfer voor bloedstolsels tot ongeveer 3,9 keer dat bij vrouwen en 3,4 keer dat bij mannen; andere risico's daalden niet.
43–46% van de mensen in de studie rookte, en hiermee kon geen rekening worden gehouden.

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