Cardiovascular outcomes in transgender individuals in Sweden after initiation of gender-affirming hormone therapy

We compared the incidence of cardiovascular disease (CVD) in transgender participants with a diagnosis of gender dysphoria (GD) with and without gender-affirming hormone therapy (GAHT) to the incidence observed in the general population. The population-based cohort included all individuals >10 years in Sweden linked to Swedish nationwide healthcare Registers (2006-16). Two comparator groups without GD/GAHT were matched (1:10) on age, county of residence, and on male and female birth-assigned sex, respectively. Cox proportional models provided hazard ratios (HRs) and 95% confidence intervals (CI) for CVD outcomes. Among 1779 transgender individuals [48% birth-assigned males (AMAB), 52% birth-assigned females (AFAB)], 18 developed CVD, most of which were conduction disorders. The incidence of CVD for AFAB individuals with GD was 3.7 per 1000 person-years (95% CI: 1.4-10.0). Assigned male at birth individuals with GD had an incidence of CVD event of 7.1 per 1000 person-years (95% CI: 4.2-12.0). The risk of CVD event was 2.4 times higher in AMAB individuals (HR: 2.4, 95% CI: 1.3-4.2) compared with cisgender women, and 1.7 higher compared with cisgender men (HR: 1.7, 95% CI: 1.0-2.9). Analysis limited to transgender individuals without GAHT yielded similar results to those with GAHT treatment. The incidence of CVD among GD/GAHT individuals was low, although increased compared with matched individuals without GD and similar to the incidence among GD/no GAHT individuals, thus not lending support for a causal relationship between treatment and CVD outcomes. Larger studies with longer follow-up are needed to verify these findings, as well as possible effect modification by comorbidity.