Trans Frauen unter Hormonen: 4,5-mal mehr Blutgerinnsel, mehr Schlaganfälle; trans Männer mehr Herzinfarkte als Frauen

Auftreten akuter Herz-Kreislauf-Ereignisse bei transgender Personen unter Hormontherapie

Kohorten- & Registerstudien Körperfremde Hormone

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

Die Studie schloss 2.517 trans Frauen und 1.358 trans Männer ein, die an der Amsterdamer Gender-Klinik behandelt und im Durchschnitt etwa 9 und 8 Jahre nachverfolgt wurden.
Trans Frauen hatten 73 Blutgerinnsel in den Venen: das 5,5-Fache der erwarteten Rate bei Frauen und das 4,5-Fache der bei Männern.
Trans Frauen hatten 29 Schlaganfälle (das 2,4-Fache der Rate bei Frauen, das 1,8-Fache der bei Männern) und 30 Herzinfarkte (das 2,6-Fache der Rate bei Frauen; nicht höher als bei Männern).
Trans Männer hatten 11 Herzinfarkte: das 3,7-Fache der bei Frauen erwarteten Rate und gleich viel wie bei Männern erwartet.
Trans Männer hatten nur 6 Schlaganfälle und 2 Blutgerinnsel, ohne klaren Unterschied zu Männern oder Frauen.
Der Ausschluss von trans Frauen, die vor 2001 begannen (als ein älteres Östrogen, Ethinylestradiol, ersetzt wurde), senkte die Blutgerinnselrate auf etwa das 3,9-Fache der von Frauen und das 3,4-Fache der von Männern; andere Risiken sanken nicht.
43–46 % der Personen in der Studie rauchten, und dies ließ sich nicht berücksichtigen.

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