ホルモンを使うトランス女性は血栓が男性の4.5倍で脳卒中も多く、トランス男性は女性より心臓発作が多い

ホルモン療法を受けているトランスジェンダーの人々における急性心血管イベントの発生

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

この研究には、アムステルダムのジェンダークリニックで治療を受けたトランス女性2,517人とトランス男性1,358人が含まれ、平均してそれぞれ約9年と8年追跡されました。
トランス女性には静脈の血栓が73件あり、女性の予想される割合の5.5倍、男性の4.5倍でした。
トランス女性には脳卒中が29件（女性の割合の2.4倍、男性の1.8倍）、心臓発作が30件（女性の割合の2.6倍で、男性より高くない）ありました。
トランス男性には心臓発作が11件あり、女性で予想される割合の3.7倍、男性で予想される割合と同じでした。
トランス男性の脳卒中は6件、血栓は2件だけで、男性とも女性とも明確な違いはありませんでした。
2001年より前（古いエストロゲンであるエチニルエストラジオールが置き換えられた時期）に開始したトランス女性を除くと、血栓の割合は女性の約3.9倍、男性の3.4倍に下がりましたが、他のリスクは下がりませんでした。
研究の対象者の43～46%が喫煙しており、これは考慮できませんでした。

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