Use of puberty-blocking hormones for gender dysphoria in New Zealand: descriptive analysis and international comparisons.

Aim: To investigate use of puberty-blocking hormones (gonadotropin-releasing hormone analogues [GnRHa]) for gender dysphoria in New Zealand. Specifically, to describe demographic characteristics and time trends in the prevalence and incidence of prescribing, and to calculate cumulative incidence (proportion) of first prescribing of GnRHa for gender dysphoria in order to make valid international comparisons.

Method: The national Pharmaceutical Collection was used to identify all dispensing from 2006 to 2023 to those aged <18, by sex/gender and age. Cumulative incidence of first prescriptions between ages 12 and 17 (which largely excludes prescribing for other indications) was calculated and compared with the Netherlands and England and Wales.

Results: In New Zealand, prescription of GnRHa for gender dysphoria started around 2011; prevalence of use increased to 2014, then more steeply to 2022, followed by a decline. Incidence data show the decline started from 2021. New Zealand, compared to the Netherlands (which started prescribing in the 1990s), had 1.7 times the cumulative incidence of first prescriptions by 2018. Compared to England and Wales up to 2020, New Zealand had 3.5-6.9 times the cumulative incidence.

Conclusion: The high rate of prescribing for probable gender dysphoria in New Zealand, and the decline after 2021, require further investigation.