The Cass Review Is Published

On 10 April 2024, the final report of the Cass Review was published, an independent inquiry into gender care for children and young people in England (source). Paediatrician Hilary Cass conducted the inquiry at the request of NHS England. The inquiry was set up in autumn 2020; an interim report appeared in 2022.

The conclusions

For the inquiry, the University of York conducted a series of systematic literature reviews. They showed that the evidence for puberty blockers and sex hormones in minors is limited: of the 50 studies on puberty blockers, one was of high quality, 25 of moderate quality and 24 of low quality, and no conclusions could be drawn about the effect on gender dysphoria, mental health and cognitive development (source). The report describes an area of 'remarkably weak evidence'. It also describes that the young people referred often have neurodiversity and/or other mental health problems (source).

The report contains 32 recommendations (source). The central message: care should be broader, with attention to the young person as a whole, and medical treatment requires great caution and should be properly researched.

What the NHS changed

On 12 March 2024, shortly before the final report, NHS England published a policy document on puberty blockers for minors with gender dysphoria (source). The Tavistock gender clinic in London closed and was replaced by regional centres. The British government subsequently also banned the sale and supply of puberty blockers on private prescriptions to under-18s for this indication; that ban was extended indefinitely on 11 December 2024 (source). The government based this on advice from the Commission on Human Medicines and on the Cass Review.

The background

NHS England commissioned the inquiry after the number of referrals to the gender clinic had risen sharply. According to the report, referrals grew exponentially from 2014; for 2021/22 it mentions about five thousand, with the caveat that double counting is possible and the unit that received the referrals registered only 3115 new ones (source). There was also a long waiting list. The Bell v Tavistock case took place in the same period and is discussed in the report.

Who is Hilary Cass?

Hilary Cass is a paediatrician. She led the Cass Review, which was set up in 2020.

Social transition and young adults

The report goes beyond medication. On social transition, in which a child begins living with a different name and pronouns, it says there is no clear evidence of positive or negative effects on mental health in children, and weak evidence in adolescents. Those who had socially transitioned earlier were more likely to go on to a medical pathway; whether social transition caused this cannot be determined (source). The report also recommends setting up follow-through services for 17- to 25-year-olds at the regional centres, so that care does not pass abruptly to adult services (recommendation 23, source).

Significance

The Cass Review is widely cited internationally, including in the Dutch debate. Its methodology has also been criticised: Noone and colleagues concluded in 2025 in BMC Medical Research Methodology that the systematic reviews made for the Review have a high risk of bias (source). See also the so-called Yale report. NICE had already assessed the evidence earlier; see the NICE reviews. Why the report is considered a turning point and what it means for the Netherlands is explained on transtijd.nl in the article about the Cass Review as a turning point in youth gender care. More information is available on the page about the Cass Review and in the archive.