One of the top scientific researchers in the world has just released a statement about gender-affirming care that has caused a huge furor. Professor Gordon Guyatt, who is among the top ~50 academics in the world in the metrics that academia values, and his less well-known colleagues released this statement about their recent work. They have just done a series of studies looking into gender-affirming care options funded by notorious anti medical treatment group SEGM.

Their statement is lengthy, but I think this bit sums it up nicely:

"…we are concerned that the assessments of the certainty of evidence using established and standard methodology are interpreted as evidence supporting denial of care to trans, nonbinary, and gender-diverse (TGD) individuals, including youth. We are concerned our findings will be used to justify denying care such as puberty blockers and hormone replacement therapy to TGD individuals. Indeed, our prior work has been used in exactly this highly problematic way.

We therefore feel compelled to make explicit our view regarding how our findings should and should not be used. Following fundamental principles of humane medical practice, clinicians have an obligation to care for those in need, often in the context of shared decision making. It is unconscionable to forbid clinicians from delivering gender-affirming care.

Moreover, following the principles of evidence-based decision-making, clinicians should always have a high respect for the autonomy of patients and their advocates. The high respect for autonomy becomes particularly important when the certainty of the evidence is low or very low. In such circumstances, clinicians should work with patients to ensure that care reflects the experience, goals, and priorities of those needing care — that is, their values and preferences.

It is profoundly misguided to cast health care based on low-certainty evidence as bad care or as care driven by ideology, and low-certainty evidence as bad science. Many of the interventions we offer are based on low certainty evidence, and enlightened individuals often legitimately and wisely choose such interventions. Thus, forbidding delivery of gender-affirming care and limiting medical management options on the basis of low certainty evidence is a clear violation of the principles of evidence-based shared decision-making and is unconscionable. The appropriate use of our work is in ensuring patients receive needed care and in helping TGD patients and their clinicians in decision making." (bolding added for emphasis).

This statement directly contradicts the public position of their funders. SEGM's website compares gender-affirming care — and particularly medical management such as puberty blockers and hormones — with lobotomies, thalidomide, and the opioid epidemic. They call for an "end to this uncontrolled experimentation on youth", referencing "The "gender affirmative" model". They say that the only way that transgender teens should receive puberty blockers, hormones, surgery, or any other gender-affirming care is within some form of carefully controlled research. While SEGM does not explicitly use the term "ban", it is impossible to see any other way that their demands could be fulfilled.

This is a fascinating situation for several reasons. Let's look at the science, and the very principled stance that Professor Guyatt and his colleagues have taken.

The Science

The new studies by Prof Guyatt and team are systematic reviews of evidence. The authors went out looking for every study that has been done on a topic, and summarized those together in one place. They have now published three papers on puberty blockers, hormones, and mastectomies in young people with gender dysphoria. In this case, "young" means under 26 years of age.

These papers appear to be very well-done, as you'd expect from the team. Professor Guyatt is, after all, one of the people who literally wrote the book on how to do this sort of study, and has been credited with coming up with the idea of evidence-based medicine in the first place.

The authors basically found the same things that we've seen time and again. There is some evidence that puberty blockers and hormones improve mental health for teenagers with gender dysphoria, but it's very low-quality data and therefore highly uncertain. The number of studies included in these newest reviews is barely different from when the Cass review funded York university to do an almost identical body of research . I'm not going to go through every paper on puberty blockers and hormones again, because nothing has really changed since the last time I wrote about it — read my Cass review series if you're interested in much more detail than anyone could ever want.

The data that we have supporting medical intervention for transgender teens remains pretty bad. Yes, there are a number of studies showing a benefit, but many of those don't even have control groups and the few that do have enormous holes that make us very uncertain about the results. Until someone does a better study — even a better observational study, perhaps using a large dataset with controls chosen from the general population and a good causal analysis structure — we will always be uncertain about whether puberty blockers and hormones improve the mental health of trans kids.

The one mildly interesting addition to the literature is the review on mastectomies. There is, again, very little data looking at mastectomies for transgender youth, but there is some plausible benefit based on a very small number of studies. Interesting read, but again certainly not definitive.

These are, frankly, unnecessary reviews. You could argue that the mastectomy one is a novel addition, but there are so few studies on mastectomies for trans youth. Also, it's the least interesting question of the bunch, because it almost exclusively concerns older teenagers. You have to wait until breast tissue stops growing for a mastectomy to be useful. The question is therefore mostly about whether 17 year old trans boys should wait a year or two and use a binder before getting a mastectomy if that's what they want. Reviewing the literature just to say that there are very few studies and that mastectomies carry known risks is a bit of a waste of time for all involved.

The other reviews have already been done. Systematic reviews are, after all, just an attempt to gather all the studies on a particular question together and apply the subjective lens of the reviewer's opinions to the data at hand. Prof Guyatt and team are better than most at doing this sort of review, but there was essentially no new evidence published between April 2022 when the York team did their searches and September 2023 when Guyatt et al did theirs. The York team are, as I said last year, excellent scientists and while I think their work had some holes they were mostly about over-interpretation of results not their methods. Both teams looked at the evidence-base and found it to be weak, which in my opinion is a reasonable assessment.

Embracing Uncertainty

The point here is that we already knew that the evidence wasn't very strong. That's not news. What the new statement from Prof Guyatt and team points out is what weak evidence means for the medical treatment of gender dysphoria.

It's important to consider the context here. There are really only three proposed ways to treat a teenager or young adult who says that their gender feels wrong. There's the 60s/70s/80s approach which we mostly describe as conversion therapy these days — manipulate and emotionally/physically abuse the kids until they stop saying things about their gender.

Then there's the model proposed by SEGM and similar organisations, which argues that young people's brains are not developed enough to decide on lifelong interventions like hormones or puberty blockers. They say that most gender dysphoria goes away by the time kids turn 20 anyway, so just give them therapy and psychiatric medications until they stop feeling trans.

Finally, there's gender-affirming care. This modality is supported by the lead professional organisation for the treatment of transgender people — the World Professional Association for Transgender Health — and promotes the idea that young people should be supported in any way possible. If they want to transition genders, they can, and medical providers are simply there to help them understand the risks and benefits and support their mental health through the process.

Of these three methods of treating children with gender dysphoria, none have strong evidence. There are few studies on gender-affirming care and many of them are weak. There are even fewer studies on conversion therapy, and also many of the methods are repugnant and awful. There are quite literally no studies at all looking at whether therapy has benefits for kids with gender dysphoria, nor whether forcing them to experience "natural" puberty is better than using medications to delay or prevent this.

The statement by the McMaster team is, therefore, precisely what you'd expect an unbiased expert in evidence-based medicine to say. If a dysphoric teen turns up at a doctor's clinic, we don't know what the best treatment is. I personally think that the current evidence is in favour of gender-affirming care, but the data isn't very good. I can see why an expert in evidence appraisal would argue that there are no proven options at all.

Much of medicine is based on evidence that isn't strong. Quite a lot of parenting advice — from breastfeeding to sleeping recommendations — is based on very weak studies. A 2023 review of the Irish national clinical guidelines found that around half of the recommendations were based on low or very low certainty evidence. There are a lot of places where we aren't sure of the best thing to do, but we still have to make some sort of decision about medical care. This is, in fact, something outlined in another 2023 paper authored by Prof Guyatt and his team at McMaster.

I almost entirely agree with Prof Guyatt and his team. Indeed, the conclusion of my lengthy series looking at the UK's Cass review makes an almost identical argument to the McMaster statement. Bad evidence doesn't mean bad clinical practice, and banning one low-quality treatment means that you are implicitly endorsing the only other treatment which has even less data to support it.

We have low certainty that gender-affirming care is the best option for transgender youth. The only way to fix that is with high-quality research, ideally either some really strong observational studies or randomized trials.

But we have even less data on the vague idea of therapy that is the main proposed alternative. We don't even know if forcing children to undergo psychological assessment makes them less likely to go on to puberty blockers or hormones at a later date, never mind how this therapy impacts their long-term mental health.

In this context, calls for bans on gender-affirming care are simply not scientific. Even calling for care to be banned outside of clinical trials is not an evidence-based point of view. That this fact has infuriated many anti-treatment advocates such as SEGM is, in my opinion, a good indication of who really cares about evidence in this debate.