Transkvinner på hormoner hadde 4,5 ganger så mange blodpropper og flere hjerneslag enn menn; transmenn flere infarkt

Forekomst av akutte kardiovaskulære hendelser hos transkjønnede personer som får hormonbehandling

Kohort- og registerstudier Kjønnsbekreftende hormoner

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

Studien inkluderte 2 517 transkvinner og 1 358 transmenn behandlet ved kjønnsklinikken i Amsterdam, fulgt i omtrent 9 og 8 år i gjennomsnitt.
Transkvinner hadde 73 blodpropper i vener: 5,5 ganger den forventede raten hos kvinner og 4,5 ganger raten hos menn.
Transkvinner hadde 29 hjerneslag (2,4 ganger raten hos kvinner, 1,8 ganger raten hos menn) og 30 hjerteinfarkt (2,6 ganger raten hos kvinner, ikke høyere enn hos menn).
Transmenn hadde 11 hjerteinfarkt: 3,7 ganger den forventede raten hos kvinner og det samme som forventet hos menn.
Transmenn hadde bare 6 hjerneslag og 2 blodpropper, uten tydelig forskjell fra verken menn eller kvinner.
Når man utelot transkvinner som begynte før 2001 (da et eldre østrogen, etinylestradiol, ble erstattet), falt blodproppraten til omtrent 3,9 ganger kvinners og 3,4 ganger menns. Andre risikoer falt ikke.
43–46 % av personene i studien røykte, og dette kunne ikke tas hensyn til.

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