Purpose: Gender affirming hormone treatment (HT) induce physical changes in transgender people. Whether HT results in an increased mortality is not well established yet. Therefore, we aim to study mortality in a large cohort of transgender people and compare this with a Dutch male and female reference population.
Materials and methods: All transgender people who visited the outpatient clinic of the VU University Medical Center, Amsterdam, the Netherlands, and started HT between 1996 and 2016, were included. For every transgender person, 5 age-matched control males and 5 age-matched control females were included, based on a random sample from the Dutch population. This cohort was linked to Statistics Netherlands (CBS) which registers the date and cause of death of all people who lived in the Netherlands since 1996. This database was searched up to 2017. Mortality rate (expressed as percentage) and relative risk (RR) with 95% confidence intervals (CI) were calculated for transwomen and transmen separately.
Results: In total, 2,134 transwomen (median age at start of HT 49 years, inter quartile range (IQR) 37-59 years) and 1,243 transmen (median age at start of HT 37 years, IQR 24-49 years) were included, with a mean treatment duration of 13 years (IQR 5-23) and 7 years (IQR 2-9), respectively. Of the included transwomen, 9.6% were deceased, compared with 6.0% of the age-matched control males (RR 1.7, 95%CI 1.4-1.9) and 4.8% of the age-matched control females (RR 2.1, 95%CI 1.8-2.5). The decease rate in transmen was 2.6%, compared with 2.6% of the age-matched control males (RR 1.0, 95%CI 0.7-1.4) and 1.7% of the age-matched control females (RR 1.6, 95%CI 1.0-2.3).
Conclusion:  This large nationwide cohort study showed an increased mortality in transwomen compared with both age-matched control males and females. The mortality in transmen was increased compared with age-matched control females, but not compared with age-matched control males. Upcoming analyses need to determine the cause of the deceases and whether this is different from the control males and females.