The newly released Cass review on transgender care for under 18s has had a seismic effect across the United Kingdom and Europe.1 Scotland and Wales promptly followed the NHS in England in ceasing the prescription of puberty “blocking” drugs outside of research protocols. The UN special rapporteur on violence against women and girls, Reem Alsalem, called the independent inquiry’s findings and recommendations “seminal” and stated that policies on gender treatments have “breached fundamental principles” of children’s human rights, with “devastating consequences.” Some charities and clinicians are disappointed with last month’s final review report. But the tone of major print and broadcast media in the UK has shifted: outlets that have previously reported criticism of gender services as transphobic now note how, as the Guardian reported, “the lack of high quality research, highlighted by Cass, has been a subject of growing unease among doctors.”

The review by Hilary Cass, paediatrician and former president of the Royal College of Paediatrics and Child Health, was commissioned by the NHS and built on the findings of Cass’s 2022 interim report. Then, she found that the evidence underpinning the treatment intensive, “gender affirming” model of care for distressed young people was “limited” and “inconclusive.” The final report is even clearer: “The reality is that we have no good evidence on the long term outcomes of interventions to manage gender related distress.”

But in the United States, where the gender affirming model is the norm, the effect of Cass’s four year investigation and final report isn’t yet obvious. “Unfortunately, Cass does not seem to be penetrating the public consciousness,” says Zhenya Abbruzzese, cofounder of the four year old Society for Evidence Based Gender Medicine (SEGM), a group of researchers and clinicians that has pushed for systematic reviews and an evidence based approach.