Continuation of gender-affirming hormones in transgender people starting puberty suppression in adolescence: a cohort study in the Netherlands

Background: In the Netherlands, treatment with puberty suppression is available to transgender adolescents younger than age 18 years. When gender dysphoria persists testosterone or oestradiol can be added as gender-affirming hormones in young people who go on to transition. We investigated the proportion of people who continued gender-affirming hormone treatment at follow-up after having started puberty suppression and gender-affirming hormone treatment in adolescence. Methods: In this cohort study, we used data from the Amsterdam Cohort of Gender dysphoria (ACOG), which included people who visited the gender identity clinic of the Amsterdam UMC, location Vrije Universiteit Medisch Centrum, Netherlands, for gender dysphoria. People with disorders of sex development were not included in the ACOG. We included people who started medical treatment in adolescence with a gonadotropin-releasing hormone agonist (GnRHa) to suppress puberty before the age of 18 years and used GnRHa for a minimum duration of 3 months before addition of gender-affirming hormones. We linked this data to a nationwide prescription registry supplied by Statistics Netherlands (Centraal Bureau voor de Statistiek) to check for a prescription for gender-affirming hormones at follow-up. The main outcome of this study was a prescription for gender-affirming hormones at the end of data collection (Dec 31, 2018). Data were analysed using Cox regression to identify possible determinants associated with a higher risk of stopping gender-affirming hormone treatment. Findings: 720 people were included, of whom 220 (31%) were assigned male at birth and 500 (69%) were assigned female at birth. At the start of GnRHa treatment, the median age was 14·1 (IQR 13·0–16·3) years for people assigned male at birth and 16·0 (14·1–16·9) years for people assigned female at birth. Median age at end of data collection was 20·2 (17·9–24·8) years for people assigned male at birth and 19·2 (17·8–22·0) years for those assigned female at birth. 704 (98%) people who had started gender-affirming medical treatment in adolescence continued to use gender-affirming hormones at follow-up. Age at first visit, year of first visit, age and puberty stage at start of GnRHa treatment, age at start of gender-affirming hormone treatment, year of start of gender-affirming hormone treatment, and gonadectomy were not associated with discontinuing gender-affirming hormones. Interpretation: Most participants who started gender-affirming hormones in adolescence continued this treatment into adulthood. The continuation of treatment is reassuring considering the worries that people who started treatment in adolescence might discontinue gender-affirming treatment. Funding: None.