This is the last piece that I’ve planned to write about the Cass review for gender identity services for children in the UK. To be honest, I hadn’t planned to write nearly this much about the document, but most of the aspects of the review that need interrogation are pretty complex, and it’s hard to get to them in fewer words.

Or maybe I’ve just been obsessing about this and wanted to share. Either way, eight pieces totalling nearly 30k words seems like enough. There is more to cover - mistakes, errors, and exclusions that I haven’t had time to get to - but at a certain point additional data tells the same story. So let’s take a final look at this scientifically flawed, problematic publication together.

This is part 8 of my series looking at the Cass review into gender identity services for children in the UK. You can find the other parts here (I will update as I add sections):

- Introduction

- Part One

- Part Two

- Part Three

- Part Four

- Part Five

- Part Six

- Part Seven

- Conclusion

The Cass review was an interesting juxtaposition. Some of the scientific arguments were very reasonable, and the York team generally did a decent job with the systematic reviews that informed the document. However, the review itself often positioned bizarre theories about gender dysphoria alongside data and evidence. I’ve recounted quite a few examples of this during my pieces, but I thought I’d share one more that I found recently:

“Research commentators recommend more investigation into consumption of online pornography and gender dysphoria is needed. Some researchers (Nadrowski, 2023) suggest that exploration with gender-questioning youth should include consideration of their engagement with pornographic content.” (Cass review, page 110)

This paragraph suggests that porn can potentially turn children trans. If you look up the reference, it is to this opinion piece from a psychiatrist. The paper itself contains no data connecting gender dysphoria to pornography, but basically argues that teen girls may view porn and become so disgusted with being women that they choose to instead become men. The paper also notes that “Girls affected by autism might be at higher risk because of their reduced mentalization capacities.”, although it does not provide any evidence that this is true.

The author of this opinion piece is a psychiatric trainee who lists their affiliation as Therapy First. Therapy First is an explicitly anti-medication group which campaigns to prevent children from being given hormones or puberty blockers for gender dysphoria - instead, they recommend psychotherapy as the first and in many cases only option. This is not evidence. It’s barely even an opinion. There is no reasonable excuse for the Cass review having included such a completely bizarre and unsubstantiated theory, especially without noting that it is entirely unsupported by even the most vague of evidence.

You can see why this series has taken so many words. This is a very minor point, but it still takes 3 paragraphs to look at the problem. And while this particular issue is minor, it’s emblematic of the problems throughout the Cass review. Evidence that is supportive of medical care is, in the document, treated with the utmost caution. Where the opinions of pro-medication clinicians are cited, they are largely dismissed because they are based on insufficient evidence.

But the beliefs of a single psychiatrist who has, as far as I can tell, never conducted any research into the topic, are accepted without any interrogation. There’s no qualifier to this paragraph. The suggestion that pornography may be causing kids to become trans is just…there.

I can’t go through every single issue in the lengthy review, there are simply too many to cover, but here are the biggest hits that we’ve looked at so far:

1. The team commissioned some generally adequate research. While there were issues with the York University’s systematic reviews, most of them were fairly good, and the conclusions are not totally unreasonable. There are definitely areas of care for transgender youth that are under-researched, and it’s not ridiculous to suggest, for example, that a randomized trial of puberty blockers would be a good idea.

2. The review, alongside workers from the NHS, conducted what is genuinely one of the biggest and most comprehensive studies of children attending a gender identity service in the world. They looked in detail at the clinical records of >3,000 children, which provided a great deal of insight into these kids’ lives and how their treatment went. Unfortunately, this report was buried in the appendices of the Cass review, but it did show that most of the fears of anti-treatment campaigners were unfounded.

3. The review also contained some clear mathematical errors. In particular, the authors falsely described the increase in transgender kids as an “exponential” rise. This was used heavily within the Cass review as a justification for all of the recommendations, which is problematic because it’s clearly wrong.

4. Throughout the review, the authors made fairly basic errors when it came to questions about detransition and regret. It’s particularly worrying that the Cass review failed to use its own data - the massive 3,000+ dataset I talked about above - to conclusively answer questions about detransition in children. This dataset showed that virtually no children in the UK detransitioned as minors after accessing gender-affirming care.

5. In terms of questions of medical treatment, the review’s arguments fell short. It’s true that puberty blockers don’t have very good evidence, but the fears raised by the review about long-term consequences were based on bizarre speculation including in at least one case a paper about rats with their ovaries removed. Hormone therapy similarly has relatively weak data supporting it, but the review’s interpretation of this data was even more flawed.

6. The only treatment that the review recommended, which is a combination of psychotherapy and social interventions, has literally no evidence whatsoever supporting it. The York team was unable to find a single study that looked at whether psychotherapy could improve gender dysphoria, but this is de facto the only treatment that the Cass review accepts for children with gender dysphoria.

To sum up - there were some areas where the Cass review did a decent job, but there were also places where the report does incredibly bizarre things. So what were some of the outcomes of this flawed publication?

Medications Criminalized

The first outcome is one that we’ve talked about before in this series - banning puberty blockers and mostly banning hormones for transgender teens. The Cass review’s FAQ still argues that their recommendation was not for a ban, which is a remarkable falsehood given what the document says and the outcome of the authors’ advocacy.

It is now a criminal offense for transgender children to own puberty blockers (it is not an offense for cisgender children). There are no specifics on the NHS guidance as to what criminal penalties children will face for possessing puberty blockers, but presumably this will be covered under existing punishments such as fines, community sentences, or custodial sentences.

Services Reduced Substantially

Before the Cass review came out, there were four gender identity clinics in the UK being run by the Tavistock and Portman trust, which is a specialist mental health provider. The interim report of the Cass review recommended entirely dismantling these clinics, and instead developing a regional network that would be locally managed by children’s hospitals. This was formally announced as policy by the NHS in 2022, with the Tavistock clinics set to close in 2023.

This sounds fine, in theory. But anyone who has worked in a large government service will know exactly how problematic this innocuous-sounding recommendation is. It is very easy for governments to close existing services - the main cost is a few redundancy payouts - but quite challenging to open new ones, especially for politically sensitive issues.

These gender identity services are a case in point. The UK government originally announced that the existing gender identity services would be closed by 2023, and immediately replaced with a new service, based on the Cass review’s interim report. This was quickly pushed back until 2024. During this time - July 2022 until April 2024 - the existing services were reportedly not taking new referrals. The new clinics began accepting patients in April 2024, but there are only two of them so far compared to the pre-existing four. The NHS reports that children have started being seen through this service. I emailed them a month ago to ask how many children have been seen since the second of April, what providers these clinics had, and a few other details. After two weeks, I was given a different email address to ask. I have not heard back from the second email address thus far.

In theory, the Cass review recommended an expansion of services that would better cater to the thousands of transgender children seeking care in the UK. In practice, this has basically eliminated care for the last two years for most trans kids. The Cass review’s data showed that most (~60%) of the patients seen at the Tavistock clinics were referred age 15-16. So a 15 year old referred to the clinic in August 2022 would be told that there were no new appointments with the clinic, and to wait until the new service was set up. In 2024, the now 17 year old would be finally contacted by the NHS.

But the gender identity service does not see patients who are over 17 - these teens are told that they should be seen by adult clinics - and due to the Cass review’s recommendations the NHS will not book in a patient for their initial appointment at an adult service until they are over 18. In other words, based on the public information about these clinics, it’s quite likely that most children referred for gender identity services in the UK since 2022 have had no care at all. I asked the NHS if this was the case, and have not yet heard back.

One of the main criticisms the Cass review levied at the previous Tavistock model was “unmanageably long waiting lists”. It’s remarkable, therefore, that one of the main outcomes of the review thus far is to drastically increase waiting times for teens who desperately need help.

More Research?

Another key recommendation of the Cass review was to increase the amount of research going on in the area of gender dysphoria in the UK. Out of the 32 total recommendations, 11 of them either directly or indirectly argue that more research is needed in this space.

This has led to the establishment of a national oversight board to “ensure research is embedded at the heart of new children and young people’s gender dysphoria services as they are shaped and developed”. One aspect of this is the promised clinical trial of puberty blockers, which still does not have an official timeline or any announcements other than the appointment of a chief investigator. The board includes a range of clinicians and researchers, such as Dr. Hilary Cass.

It is, however, not entirely clear what this board will do. More evidence is always good, and I think having at least one RCT of puberty blockers will be helpful, but there’s no public plan that I could find on what research this board will oversee beyond that RCT. The Cass review made several specific recommendations - such as doing a national data linkage study - are these going to take place? It’s hard to know.

It’s also notable that the key aim of the board is not to improve the evidence-base of gender dysphoria treatments. The webpage does discuss the implementation of “evidence-based best practice”, but that’s a fairly nebulous term. The Cass review considered totally unevidenced psychological treatments the best option for trans teens, which makes the stated direction of this oversight board less than reassuring.

There’s also one area that the board is still glaringly missing. They have spots open for people with lived experience - people who were treated by the NHS at a youth gender clinic.

More research can be great. It could also be a politically-motivated waste of time that provides no new information. As it stands, it is very hard to know what direction the NHS will take with their new mandate for research.

Evidence Bereft Medicine

Another consequence of the review is that children in the UK who have gender dysphoria are now going to be treated using the worst possible evidence: none. This is something that I’ve noted before, but it is worth repeating. The Cass review’s own commissioned report from York University found that there has never been a study of psychological or psychosocial interventions aimed at improving gender dysphoria in children. The review itself noted that:

"The University of York concluded that there is limited research evaluating outcomes of psychosocial interventions for children and adolescents experiencing gender incongruence, and low quality and inadequate reporting of the studies identified. Therefore, firm conclusions about their effects cannot be made.” (Cass review, page 154)

And yet, this is the only therapeutic choice that the review recommends, and indeed now the only legal option in the UK for children with gender dysphoria until age 16. Depressing.

Alternatives

I’d like to end this lengthy series by pointing out some alternatives. As I’ve said, in some places I do agree with the Cass review’s data, despite the major flaws that the report had in other areas.

For example, the recommendations that the Cass review made that children with gender dysphoria should be seen in high-quality services staffed by clinicians with adequate training. Given that the most experienced clinicians in the country are those who worked in the old Tavistock clinics, a very obvious first step would be to immediately reopen the old clinics and start accepting new referrals, while also opening up the proposed eight additional clinics in the UK.

Similarly, the review recommended that children with gender dysphoria should receive screening for autism and mental health conditions, and also that standard psychological and psychiatric therapies should be used to treat these cooccurring issues. The review’s data from the Tavistock clinics showed that this was already occurring, which also supports the immediate reopening of these services. We could argue about whether reopening the service would be the best option, but it’s clearly an alternative to providing few services at all.

It’s obvious that we need more data on treatments for children with gender dysphoria. For puberty blockers in particular, the data is extremely weak. Regardless of whether you support medical interventions for trans kids or not, the fact remains that the only way to realistically answer the question is to conduct more and better research. But such research doesn’t have to take place in a vacuum. For example, the Cass review could’ve recommended that puberty blockers should only be used in a clinical trial, but that they should not be banned in other settings until this clinical trial started.

The review called for more and better data on trans children in general, and again this does seem important. There are many questions that only better data can answer. For example, there have recently been claims that there was an explosion in suicides for patients on the gender identity service waiting list after the NHS started limiting services from this clinic in 2021 and stopped seeing new patients in 2022. These claims have been disputed. Unfortunately, both sides of this argument are using extremely limited data - they’re basically reviewing meeting minutes of the Tavistock board and arguing about what those minutes show.

It would be trivially easy for the NHS to determine the rate of suicide for children attending and referred to the gender identity services in the UK by year. If there has been a dramatic increase in suicides since the NHS substantially limited services for children with gender dysphoria, this would be extremely important information to rapidly assess and publish. As someone who has worked with datasets similar to the ones that the NHS has on hand, I’d estimate that this question could be answered conclusively in less than a week by an experienced statistician. Frankly, I’d be unsurprised if the NHS already had looked into this question in an internal report somewhere.

The point is that more and better data is useful, but only if you ask the right questions and publish the answers. The NHS already has sufficient data to quite robustly answer, say, the question of what the rates of hospital attendance are for children with gender dysphoria who are or are not prescribed puberty blockers. In theory, this is a vital, urgent question that needs to be answered by the NHS, because if puberty blockers do show a benefit then the ban is likely to be unjustified. But instead of recommending such a study, the Cass review recommended an indefinite ban until such a time as a still uncommenced trial finishes and reports its results.

Opinions

All of this brings me back to the point I made in the previous post on the review - the key weakness of the Cass review is not the evidence itself, but how that evidence is interpreted. Science is about facts, but policy is about balancing different opinions on what to do with those facts.

Let us be clear - most of what the Cass review said, outside of the direct quotation of scientific research, was opinion. This is not an attack on Dr. Cass, who is an eminently qualified and experienced clinician, it’s a fairly simple fact. The scientific element of the review consisted of one qualitative study, a series of systematic review, and the retrospective analysis of clinical records.

But there are already dozens of systematic reviews on this topic. There are a many qualitative studies. Of the actual data generated by the review, the only thing that substantially added to the literature on treatment for transgender children was the retrospective analysis, and the authors of the Cass review shunted it deep into the appendices while dismissing the findings for bizarre and spurious reasons.

When the review says things like puberty blockers for trans kids are:

“blocking the normal rise in hormones that should be occurring into teenage years, and which is essential for psychosexual and other developmental processes” (Cass review, page 174).

That is an opinion. Actually, it’s two opinions - that there is a specific normative rise in hormones for transgender children, and that this rise is essential for developmental reasons. This isn’t some inviolable fact, it’s something that the authors believe based largely on research done on rodents and speculation about psychosexual development. Some people would argue that a “normal” rise in hormones is damaging for transgender children, and that this harms their psychosexual development. The data isn’t sufficient to definitively say who is right, but it is worth noting that the people who disagree with the Cass review’s interpretation are mostly transgender people and clinicians who actually treat trans kids.

Regardless, the point is that the Cass review is not the objective accounting of truth that many commentators have positioned it as. A recent article described it as “one of the most in-depth, evidence-based reviews of an area of healthcare ever undertaken”, but this is pretty misleading. The Cass review was certainly extensive, but that doesn’t mean that the findings are necessarily true. As with any review, much of the Cass publication is simply reflective of the beliefs and opinions of its authors. In some cases, as I’ve discussed, the review contains statements that are false regardless of what your position on healthcare for transgender children is.

Take the “exponential” rise in transgender children that the review spends so much time on. It’s true that there has been a dramatic rise in the number of children with gender dysphoria. The rise mostly occurred between 2011-2015, and has plateaued since. These are facts. One theory that may explain the facts is that this is caused by changing diagnostic criteria - when we changed the diagnosis from gender identity disorder to the much broader gender dysphoria, this included many more children. We’ve seen this exact trend happen with everything from autism to diabetes, and we know that broadening diagnostic criteria almost always results in more people with a condition.

Another theory is that these changes were caused by the internet. Specifically, that pornography, Instagram, and online forums have ‘infected’ children with the belief that they have been assigned the wrong gender, or that these online services cause psychological harm which manifests in some kids as trans identification.

The Cass review treated these two theories unequally. The first possible explanation, which I would argue is by far the most likely, was ignored completely. The second possible explanation was given a lengthy and in-depth discussion:

“The striking increase in young people presenting with gender incongruence/dysphoria needs to be considered within the context of poor mental health and emotional distress amongst the broader adolescent population, particularly given their high rates of co-existing mental health problems and neurodiversity. Internationally, there have been increasing concerns about the mental health of Generation Z. The reasons for this are highly speculative, although there is ongoing debate about the contribution of excessive smartphone use and social media as discussed above.” (Cass Review, page 110).

The entirety of Chapter 7 and much of Chapter 8 of the review is dedicated to the speculative series of ideas that a) the internet/social media is causing children to have worse mental health, b) worse mental health can cause gender dysphoria, particularly in young girls, therefore c) the internet is making children trans. None of this has any evidence whatsoever, and as far as speculative theories go it’s hardly convincing. The link between pornography and transgender identification doesn’t even have a vague correlation - porn use skyrocketed long before rates of gender dysphoria increased.

The point is that the scientific findings of the Cass review are mostly about uncertainty. We are uncertain about the causes of a rise in trans kids, and uncertain about the best treatment modalities. But everything after that is opinion. The review did not even consider the question of whether normal puberty is a problem for transgender children, or whether psychotherapy can be harmful. That’s why these are now the only options in the UK - medical treatments were assumed to be harmful, while non-medical interventions (or even no treatment at all) were assumed harmless.

The outcomes of the review are, in a word, bad. It seems that children with gender dysphoria in the UK in 2024 are more likely to be held by the police than see a specialist medical provider for their issues. Existing services have been dismantled, and the NHS cannot even reply to queries as to when the new proposed services will catch up to the backlog. Regardless of what you think about gender identity services, all of this is a huge issue. The old system had serious flaws, but it’s not clear that the new system is even up and running.

I can’t end this series with a wonderful message. As far as I can tell, there’s no one truth that leaps out of the data. Gender-affirming care appears to have more support than the alternatives, but that’s not a definitive answer by any means. In an area with a dearth of evidence, I’d argue that the most important voices are the clinicians directly involved trans health and transgender people themselves - voices that were largely ignored in the governance, oversight, and publication of the Cass review.

What we can say with some certainty is that the most impactful review of gender services for children was seriously, perhaps irredeemably, flawed. The document made numerous basic errors, cited conversion therapy in a positive way, and somehow concluded that the only intervention with no evidence whatsoever behind it was the best option for transgender children.

I have no good answers to share, but the one thing I can say is that the Cass review is flawed enough that I wouldn’t base policy decisions on it. The fact that so many have taken such an error-filled document at face value, using it to drive policy for vulnerable children, is very unfortunate.