Hilary Cass sent a document to every single MP and Peer, justifying and defending the puberty blockers trial

Have you got any info about this clinical trial?

Really? You are not fully aware already? Linking news story as out and about and first Google result. You will be able to find it from here

https://www.bbc.co.uk/news/uk-55282113

So this is what we're discussing.

Diagnosis of gender incongruence according to ICD-11, which includes:
a. Strong desire to be a different gender than the birth-registered sex.
b. Strong dislike of sexual anatomy or anticipated secondary sex characteristics.
c. Gender Incongruence persisted for a minimum of 2 years.
d. Strong desire to ‘transition’ and live as the experienced gender.

The diagnosis is based on the desires and likes and dislikes of children.
Where is the science? Is there any other medical condition which is similarly diagnosed based on the desires and likes and dislikes of children?

And then this paragraph which you quoted from the protocol in your post at 23.17 last night:

"Hence currently decisions about care are made in the context of very limited
evidence and against a background of strong personal preferences. This is
particularly pertinent for a condition in which intervention decisions rely heavily on the preferences of relatively young children and adolescents who are at a developmental stage intrinsically characterised by exploration of personal identity. Many healthcare professionals and parents/caregivers have expressed concerns about over-reliance on the views of CYP at this dynamic and formative developmental stage and request clearer and more objective clinical evidence to guide decision-making in the interests of longer-term positive outcomes."

They recognise that these are children who are going through a turbulent period of their lives, which is characterised by exploring their 'personal identity'. And yet they still propose that locking them into their pre-pubescent phase of identification as the opposite sex is an appropriate course of action. How does this help with the identity formation which should be happening at puberty?

And once again, they talk about the personal preferences of children for this treatment when they are still too young to understand the nature of adult relationships and sexuality and the effect of this treatment on their lives as adults.

Insanity.

Ah, that is not a clinical trial, it is a study, which is not the same thing.

As it says in your article “The study had no control group - with children who did not take puberty blockers - to enable the researchers to compare results with.
So, it is hard to infer cause and effect or draw conclusions as to the potential harms or benefits of this treatment.”

I'd like to point out the bleeding obvious to most posters here, but it is important.

The ICD-11 states
"a. Strong desire to be a different gender than the birth-registered sex."

Why is it phrased like that? Using both 'gender' and 'sex' in the same sentence. Are they trying to say that gender means the same thing as sex? If so, then why not simply say - a strong desire to be a different sex than what they are. Wouldn't that be clearer. Why the awkward language?

Or, as we are often told, do 'gender' and 'sex' have two different meanings? Then how can changing one be relevant to the state of the other? What is the connection? What does each word mean?

When reading the full ICD entry the mix of words continues, such as saying "a strong desire for the primary and/or anticipated secondary sex characteristics that match the experienced gender" - confusing!

Then it becomes clearer.

Full text from ICD-11 (my emphasis)
icd.who.int/browse/2026-01/mms/en#344733949

"Gender incongruence of childhood is characterised by a marked incongruence between an individual’s experienced/expressed gender and the assigned sex in pre-pubertal children. It includes a strong desire to be a different gender than the assigned sex; a strong dislike on the child’s part of his or her sexual anatomy or anticipated secondary sex characteristics and/or a strong desire for the primary and/or anticipated secondary sex characteristics that match the experienced gender; and make-believe or fantasy play, toys, games, or activities and playmates that are typical of the experienced gender rather than the assigned sex. The incongruence must have persisted for about 2 years. Gender variant behaviour and preferences alone are not a basis for assigning the diagnosis."

It's sexism.

It says "Gender variant behaviour and preferences alone are not a basis for assigning the diagnosis" and yet the whole thing is a list of preferences.

This is a massive problem at the point of diagnosis, and needs to be re-examined before experimenting on children.

What control group does the proposed clinical trial have?

It didn't have a control group, it was indeed an observational longitudinal clinical study, or a cohort study, which, after systematic reviews and randomised trials, is the third best level of evidence.
However, why was it missing the control group?
The first Research Ethics Committee (REC) recommended a randomised trial, the Tavistock said no, and resubmitted to another committee, that approved the study. They had the opportunity to get it right, but they declined, and sat on the data until Keira Bell's judicial review finished. They also enrolled in the treatment new patients before the study was complete.
Investigation into the study 'Early pubertal suppression in a carefully selected group of adolescents with gender identity disorders' - Health Research Authority
I would argue that this new trial, which randomises the intervention with a delay of one year, doesn't provide a real randomised control group. I understand that in this social context it will be impossible to conduct a proper randomised trial, but the Pathway trial won't be much better of the Tavistock one, or of this one:
Mental and Emotional Health of Youth after 24 months of Gender-Affirming Medical Care Initiated with Pubertal Suppression | medRxiv

This lecture (given in Oct 2025) by Michael Biggs is very interesting on the history of the various trials / studies.

https://pmc.ncbi.nlm.nih.gov/articles/PMC12966359/

It includes some of his analysis of the Tavistock's data on bone density:

"We know that there is one negative side effect which is bone density. Even the gender clinicians will admit this, but I don’t think they’ve quite admitted just how bad it is. Figure 2 shows my re-analysis of data that was presented by Butler and colleagues from the early intervention study. 19 The data were only available because I made that complaint to the Health Research Authority. The authors say that if you look at the bone density of kids after 2 years on puberty blockers, well, it goes down – relative to the norm for their sex and age – but it’s not really a big deal. In fact, they conclude that we shouldn’t be wasting money on expensive bone density scans. 20 In fact, when I analysed the data, you can see that, actually, a significant minority of these kids have really low bone mineral density. The bell curve is what you’d expect for this age and sex and the grey bars are what we actually find after 2 years of puberty blockers. You can see a significant number of kids below −2 which is a risk of osteoporosis. Even in this small sample (24 for the spine and 21 for the hip), you can see that there are quite a few who are below −3 for the spine, so that is really extreme lack of bone density for their age and sex. In terms of the longer-term consequences of that, we know now that a Swedish adolescent who was taking puberty blockers suffered from severe osteoporosis and indeed there were a number of kids who were having problems with bone density which led the Swedish authorities to say, we’re no longer going to offer this as a regular treatment."

One might discover whether a same-sized group of children the same age as the ones being sacrificed for this new PB trial, but who were not put onto PBs, suffered any of the side effects associated with PBs, but I think we already know that they are very unlikely to indeed.

They've had to be quite clever with this because obviously you can't really have a placebo group who think they are being given puberty blockers as at some point they'll realise, so within the trial they are randomising the participants to the treatment arm and delayed treatment arm who will get the puberty blockers after a year. This will provide some comparison within the first year between those who get the blockers immediately and those who don't - and they expect to see some divergence in results that they can study over the course of the trial.

In addition, they will be recruiting a group of 3600 children who are attending gender clinics into the longitudinal Horizon study over 5.5 years who be filling out questionnaires over that time. A subset of 300 of those will be recruited into Horizon Intensive who will be roughly matched to the characteristics of those on the clinical trial, (sex, age, neurodivergence etc) to provide a control group. They will have the same labs, bone scans, cognitive assessments as the puberty blocker trial but without the puberty blockers. Then a subset of both the clinical trial cohort and the Horizon Intensive cohort (called Pathways Connect) will also have the MRIs.

So the control group aren't enrolled in the trial, but are enrolled in the sister study.

It's good that there will be some comparison. However, from what I've read, all children eligible for puberty blockers will be enrolled in the trial. Meaning the comparison group is automatically different, made up of those that do not want puberty blockers and those ineligible. Considering some of the exclusion criteria is unstable mental health, safeguarding concerns, and family circumstances, it could be a significantly different group. This will need to be considered when analysing results.

It's also disappointing that there is no comparative group based on an alternative therapeutic treatment. I'm sure they will all get some form of psychological support, but it does seem no thought has been put into alternative approaches and using this trial as a means to compare results. Instead they are looking at puberty blockers sooner or a bit later, as if they are the only option.

Regardless, hopefully this trial will be stopped as it is flawed in much bigger ways.

@noblegiraffe As it appears that you are in favour of this trial going ahead, could you comment on these issues?

It seems that this treatment is given because of a child's desires, preferences and behaviour. What is it they're trying to achieve with this treatment? Why are puberty blockers the preferred treatment for this 'condition'?

In fact, why is gender nonconformity being treated as a medical condition? Because despite the declaration "Gender variant behaviour and preferences alone are not a basis for assigning the diagnosis" there is actually nothing else in the diagnostic criteria.

@Fidgetbreak
It's also disappointing that there is no comparative group based on an alternative therapeutic treatment. I'm sure they will all get some form of psychological support, but it does seem no thought has been put into alternative approaches and using this trial as a means to compare results. Instead they are looking at puberty blockers sooner or a bit later, as if they are the only option.

I agree.

I don't think it is and I want them to stop giving them to children.

I don't think it is

What is this in reply to?

A medical condition.

So are you saying you don't think so-called 'gender incongruence' is a medical condition?

Your posts on here seem to support the trial. Why do you support a trial which involves harmful drugs being given to children for something which isn't a medical condition?

Because thousands of kids globally are being given these drugs, without them having been properly tested or subject to a clinical trial.

Clinicians are prescribing them based on the idea that they are helpful to these kids for various reasons, including 'fully reversible' 'time to think' etc etc.

And they're probably going to keep doing it, because of 'protect trans kids' 'don't deny trans kids lifesaving healthcare' etc etc.

At the moment, we have two sides shouting at each other with crappy evidence supporting each position.

If we could take the opportunity to properly study a small subset of the children who are taking these drugs, do the MRIs, the bone density scans, the cognitive tests and can comprehensively document the harms that don't outweigh the benefits, then we have a chance to shut this crap down far more quickly than just hoping that it all blows over eventually.

Do we really need to test these drugs on physically healthy children just because quacks all over the world are giving them to other children?

At the moment, we have two sides shouting at each other with crappy evidence supporting each position.

Really? Is that really how you see the current situation? Is it 'crappy evidence' to say that people can't change sex and that children shouldn't be medicated for failing to conform to outdated gender stereotypes?

I'm afraid I can't agree with you that perfectly physically healthy children should be used as lab rats to confirm that the harms outweigh the benefits of these drugs.

Edited to add: What sort of benefits do you think the people in charge of this trial expect to see in their young patients? What does a successful outcome look like that would convince them (and others) that this is an appropriate treatment?

Your posts on here seem to support the trial. Why do you support a trial which involves harmful drugs being given to children for something which isn't a medical condition?

I asked @noblegiraffe this question, as did a lot of other posters, about 30 pages ago, and the answer is: "If we do this trial on UK children, it might stop people in other countries [not the UK, because puberty blockers are already illegal here] from giving puberty blockers to their children."

That's it, I'm afraid. We should experiment on UK children in the hope that other people somewhere will stop harming other children. Hopefully. Maybe.

I see we haven't moved on from that rigid position at all.

It's like the trolley problem. Currently the trolley is headed towards 5 kids. It could be switched to 1.

Other people prefer to just ignore the 5 kids.

People also ignore the fact that not putting kids on the puberty blocker trial certainly isn't preventing them from being given puberty blockers.

Nor that it is hard to prosecute people who deliberately run their clinic from a different country.

Who in the UK is purchasing the drugs for the children? Who is injecting them? Perhaps as they are in the UK, breaking UK laws, they could be prosecuted.

Except it isn't. It's more like there's a trolleyfull of 246 children who are all going to be injured in some way, guaranteed, if we don't stop the trolley. But you want to let the trolley continue, because at the bottom of the hill, there might be one child who is about to be hit by a car, and if we swerve the trolley just enough, it might nudge the car, so it doesn't hit the one child.

But all of the other children are still going to be injured.

That's what you have continued to advocate for over 30 pages of a thread. It's unbelievable.