“the current best available evidence about the effects of puberty blockers in the population of interest is very low certainty”
Two Canadian reviews, similar in nature to the Cass Review, Puberty blockers for gender dysphoria in youth: A systematic review and meta-analysis and Gender affirming hormone therapy for individuals with gender dysphoria aged <26 years: a systematic review and meta-analysis were released in January of 2025.
The reviews, commissioned by the Society for Evidence Based Medicine (SEGM), were executed and written by researchers Gordon Guyatt, Chan Kulatunga-Moruzi, Anna Miroshnychenko, Sara Ibrahim, Yetiani Roldan, Steven Montante, Rachel Couban, Romina Brignardello-Petersen out of Hamilton, Ontario’s McMaster University. They used a systematic review method called “meta-analysis” to assess a host of existing studies, which once again showed that there is poor evidence for the use of both GnRH Analogues (puberty blockers) and synthetic sex hormones for young people experiencing transgender ideation, commonly referred to as gender dysphoria (GD).
This research method, and the studies’ findings, echo those of the UK’s Cass Review that was published last year, has since led to the closure of the infamous Tavistock Clinic and firm restrictions on the use of GnRH Analogues in children in the United Kingdom, and continues to inform so-called gender affirming care practices in some countries.
In the first study, dealing with the use of synthetic sex hormones in individuals under the age of 26, also referred to as gender affirming hormone therapy for youths, researchers assessed 24 studies that “provided mostly very low certainty evidence regarding GD, global function and depression, depression and bone mineral density”. Simply put, the evidence of safety and efficacy to support the continued use of these experimental treatments is just not there.
In the second study with a focus on the use of GnRH Analogues (puberty blockers), also in individuals under the age of 26, the results “provided very low certainty of evidence addressing gender dysphoria, global function, depression, and bone mineral density”. Again, in all areas researched, the evidence that should be required for Canadian medical AND mental health organizations and individuals to continue these practices is simply not there.
Shockingly, but not surprisingly, the running theme throughout the result sections in both reviews is that “[t]he evidence is very uncertain about…”, referring to items such as “the effect of puberty blockers on gender dysphoria at long term follow-up”, “the effect of GAHT [synthetic sex hormones] on depression”, “the effect of puberty blockers on depression at long term follow-up”, and “the effect of GAHT on death by suicide”. The idea that the gender affirming care model is life saving, reduces suicide risk, and improves mental health and general well-being is simply not true according to these systematic reviews and others around the world.
Currently, the Canadian Paediatric Society’s position is one of “an affirming approach to caring for transgender and gender-diverse youth”, however, the both Canadian reviews show that there is not enough evidence to support this position, and certainly not enough to toss aside the basis of modern medicine, which is to first do no harm.
