The Cass review: an opportunity to unite behind evidence informed care in gender medicine

At the heart of Hilary Cass’s review of gender identity services in the NHS is a concern for the welfare of “children and young people” (doi:10.1136/bmj.q820).1 Her stated ambition is to ensure that those experiencing gender dysphoria receive a high standard of care. This will be disputed, of course, by people and lobbying groups angered by her recommendations, but it is a theme running through the review. Cass, a past president of the UK’s Royal College of Paediatrics and Child Health, seeks to provide better care for children and adolescents on one of the defining issues of our age. Her conclusion is alarming for anybody who genuinely cares for child welfare: gender medicine is “built on shaky foundations” (doi:10.1136/bmj.q814).2

That verdict is supported by a series of review papers published in Archives of Disease in Childhood, a journal published by BMJ and the Royal College of Paediatrics and Child Health (doi:10.1136/archdischild-2023-326669 doi:10.1136/archdischild-2023-326670 doi:10.1136/archdischild-2023-326499 doi:10.1136/archdischild-2023-326500).3456 The evidence base for interventions in gender medicine is threadbare, whichever research question you wish to consider—from social transition to hormone treatment.

For example, of more than 100 studies examining the role of puberty blockers and hormone treatment for gender transition only two were of passable quality. To be clear, intervention studies—particularly of drug and surgical interventions—should include an appropriate control group, ideally be randomised, ensure concealment of treatment allocation (although open label studies are sometimes acceptable), and be designed to evaluate relevant outcomes with adequate follow-up.

One emerging criticism of the Cass review is that it set the methodological bar too high for research to be included in its analysis and discarded too many studies on the basis of quality. In fact, the reality is different: studies in gender medicine fall woefully short in terms of methodological rigour; the methodological bar for gender medicine studies was set too low, generating research findings that are therefore hard to interpret. The methodological quality of research matters because a drug efficacy study in humans with an inappropriate or no control group is a potential breach of research ethics. Offering treatments without an adequate understanding of benefits and harms is unethical. All of this matters even more when the treatments are not trivial; puberty blockers and hormone therapies are major, life altering interventions. Yet this inconclusive and unacceptable evidence base was used to inform influential clinical guidelines, such as those of the World Professional Association for Transgender Health (WPATH), which themselves were cascaded into the development of subsequent guidelines internationally (doi:10.1136/bmj.q794).7

The Cass review attempted to work with the Gender Identity Development Service (GIDS) and the NHS adult gender services to “fill some of the gaps in follow-up data for the approximately 9000 young people who have been through GIDS to develop a stronger evidence base.” However, despite encouragement from NHS England, “the necessary cooperation was not forthcoming.” Professionals withholding data from a national inquiry seems hard to imagine, but it is what happened.

A spiralling interventionist approach, in the context of an evidence void, amounted to overmedicalising care for vulnerable young people. A too narrow focus on gender dysphoria, says Cass, neglected other presenting features and failed to provide a holistic model of care. Gender care became superspecialised when a more general, multidisciplinary approach was required. In a broader sense, this failure is indicative of a societal failure in child and adolescent health (doi:10.1136/bmj.q802 doi:10.1136/bmj-2022-073448).89 The review’s recommendations, which include confining prescription of puberty blockers and hormonal treatments to a research setting (doi:10.1136/bmj.q660), now place the NHS firmly in line with emerging practice internationally, such as in Scandinavia (doi:10.1136/bmj.p553).1011

Cass proposes a future model of regional multidisciplinary centres that provide better access and, importantly, standardised care for gender dysphoria, including a smoother transition between adolescent and adult services. Staff will need training. All children and young people embarking on a care pathway will be included in research to begin to rectify the problems with the evidence base, with long term outcomes being an important area of focus. An already stretched workforce will need to extend itself further (doi:10.1136/bmj.q795 doi:10.1136/bmj-2024-079474).1213 In the meantime, some children and young people will turn to the private sector or online providers to meet their needs. The dangers in this moment of service transition are apparent.

But it’s also a moment of opportunity. Families, carers, advocates, and clinicians—acting in the best interests of children and adolescents—face a clear choice whether to allow the Cass review to deepen division or use it as a driver of better care. The message from the evidence reviews in Archives of Disease in Childhood is as unequivocal as it could be. Cass’s review is independent and listened to people with lived experience. Without doubt, the advocacy and clinical practice for medical treatment of gender dysphoria had moved ahead of the evidence—a recipe for harm.

People who are gender non-conforming experience stigmatisation, marginalisation, and harassment in every society. They are vulnerable, particularly during childhood and adolescence. The best way to support them, however, is not with advocacy and activism based on substandard evidence. The Cass review is an opportunity to pause, recalibrate, and place evidence informed care at the heart of gender medicine. It is an opportunity not to be missed for the sake of the health of children and young people. It is an opportunity for unity.