New report critiques UK transgender youth care research study

Editors note: This story previously stated the new report as a Yale study. The study was performed in part by Yale researchers and is not affiliated with the institution.

A new report released by researchers from the Yale Law School, Yale School of Medicine, Oregon Health & Science University, Northwestern University and others criticizes the often-cited Cass Review on gender-affirming care for transgender youth, commissioned by the National Health Service (NHS) in the United Kingdom.

The review, released in April, was performed by Dr. Hillary Cass, a former president of the Royal College of Pediatrics and Child Health, amid a rise in referrals to NHS' gender services. Her review – which calls for more research, more support, and more caution around gender-affirming care – has been cited in the NHS decision to restrict the prescribing of puberty-pausing medications, also known as puberty blockers, to children and young people under 18 years old in the U.K.

In the U.S., gender-affirming care remains a hot-button issue in the political and medical arenas. At least 25 states have enacted restrictions on care for transgender youth since 2022, according to the Human Rights Campaign.

The Cass review was cited in recent, successful legislative efforts in Indiana to uphold a 2023 law that prohibited physicians from providing "gender transition procedures" to anyone younger than 18 years old, with certain medical exceptions.

The new report – which states it was authored by a team of researchers and clinicians that has "86 years of experience working with 4,800 transgender youth," and "has published 278 peer-reviewed studies, 168 of which are related to gender-affirming care" – takes issue with several aspects of the Cass Review in their critique, saying that it "obscures key findings, misrepresents its own data, and is rife with misapplications of the scientific method." It also accuses the Review of speculating about data on transgender patients, and criticizes certain statements made in the Review about concern over gender care referrals, early medical intervention, and more.

Yet despite being cited in the NHS decision to restrict prescribing puberty blockers to minors, the report notes that the Cass Review does not recommend a ban on trans youth care. It also notes that it consistently makes recommendations that are in line with international gender-affirming medical care guidelines by the World Professional Association for Transgender Health (WPATH) and the Endocrine Society, a professional medical organization that is "dedicated to providing the field of endocrinology with timely, evidence-based recommendations for clinical care and practice," according to its website.

In response to an ABC News request for comment, the team that authored the Cass Review said in a statement that the research that "underpins" the Review's findings "looked at 237 papers from 18 countries, providing information on a total of 113,269 children and adolescents," and was subject to peer review.

"In making her recommendations, Dr. Cass had to rely on the currently available evidence and think about how the NHS can respond safely, effectively, and compassionately," the Review team told ABC News.

The statement continued, "The body of research on gender care for children and young people was strikingly poor compared to other areas of child and adolescent healthcare where life changing interventions are given, meaning there is not a reliable evidence base upon which to make clinical decisions, or for children and their families to make informed choices."

Spike in gender service referrals

The Cass Review repeatedly claims that the increase of referrals for gender-affirming care in the U.K. was "exponential," and that social acceptance of transgender identities is unlikely to be the sole explanation for the rise.

"While it certainly seems to be the case that there is much greater acceptance of trans identities, particularly among younger generations, which may account for some of the increase in numbers, the exponential change in referrals over a particularly short five-year timeframe is very much faster than would be expected for normal evolution of acceptance of a minority group," Cass states.

In the new report, researchers counter that the increase in referrals to the U.K.'s Gender Identity Service is not exponential, and points to Cass's own data on referrals, which they say actually shows the number of referrals plateaued, and then decreased starting in 2017. A graph included in the Cass Review that shows a spike from 2021 to 2022 in child and adolescent referrals for gender dysphoria is accompanied by a note that states there is "a strong possibility that there was double counting" of referrals during the time period.

"While there certainly is an increase in referrals, describing this increase as 'exponential' is a serious error that fuels concern that the Review is too often more interested in subjective polemics than in scientific accuracy," the Yale report says.

Research quality on gender-affirming care

The Cass Review also criticized the evidence supporting the need for gender-affirming care. It concluded that "while a considerable amount of research has been published in this field, systematic evidence reviews demonstrated the poor quality of the published studies, meaning there is not a reliable evidence base upon which to make clinical decisions, or for children and their families to make informed choices."

The collective of experts counter in their report that the Cass Review's "recommendations are informed by a flawed concept of evidence." It says the Review "fails to recognize the nuances of evidence quality measures"; that it "does not follow established standards for evaluating evidence and evidence quality"; that it "casually discusses evidence quality and does not define it, contravening standard practice in scientific evaluations of medical research"; and that it "fails to contextualize the evidence for gender-affirming care with the evidence base for other areas of pediatric medicine."

"If high-quality evidence were a prerequisite for medical care, we would all be worse off," the Yale report further states. "Moderate, low, and very low-quality evidence," as defined by what the report says is "one of the most widely accepted frameworks for determining evidence quality," and "informs necessary, high-value care at every stage of life."

The Cass Review team states in an online FAQ that "the approach to the assessment of study quality was the same as would be applied to other areas of clinical practice – the bar was not set higher for this Review."

A subsequent clarification in the FAQ further states: "The same level of rigor should be expected when looking at the best treatment approaches for this population as for any other population so as not to perpetuate the disadvantaged position this group have been placed in when looking for information on treatment options."

Early intervention concerns

The new report also takes issue with what it calls "unfounded speculation" in the Cass Review that "social transition and puberty-pausing medications may cause harm by putting youth onto a medical path." It further notes instances in which they assert the Cass Review "expresses concern that early supportive interventions, such as social transition and puberty-pausing medications, lock young people into irreversible care."

For example, while stating that for some young patients, the "best outcome" will be gender transitioning, the Review also argues that "those who had socially transitioned at an earlier age and/or prior to being seen in clinic were more likely to proceed to a medical pathway," and that "the vast majority of people started on puberty blockers proceed from puberty blockers to masculinizing/feminizing hormones" – an "altered trajectory, culminating in medical intervention which will have life-long implications."

The Cass Review also cautions that young people who transition before they experience life as the gender with which they do not identify "may have no frame of reference to cause them to regret or detransition, but at the same time they may have had a different outcome without medical intervention and would not have needed to take life-long hormones."

"It is completely unscientific and inappropriate to expect a young person, regardless of their gender identity, to 'try out' life as a gender they do not identify with – as the Review supposes transgender youth should," the Yale report states. It further says that "The Review's own data show that most referred patients are never subsequently referred to pediatric endocrinology and even fewer receive medical interventions."

The report argues that continuing care isn't necessarily cause for alarm or concern, and that "The Review does not consider the most likely explanation for why most youth who receive early, supportive interventions continue onto gender-affirming hormone therapy: that they are indeed transgender."

"It is not social transition and puberty-pausing medications that drive a persistent transgender identity," the Yale report asserts. "It is a transgender identity that drives social transition and subsequent medical interventions."

Detransitioning and regret

The Cass Review asserts that "the percentage of people treated with hormones who subsequently detransition remains unknown due to the lack of long-term follow-up studies, although there is suggestion that numbers are increasing."

However, in the Review's audit of 3,306 patients who were discharged from the U.K. Gender Identity Service (GIDS), fewer than 10 patients transitioned back to their birth-registered gender – which the collective of researchers note is "a 'detransition' date of 0.3%."

The new report also states that it is "exceedingly rare that an individual would later determine that they are not transgender" after receiving clinical transgender care and support. "A person who regrets receiving care may continue to identify as transgender; another who stops medications may not experience regret, and one who stops identifying as transgender may not regret receiving medical care," the report says.

A report in JAMA Pediatrics noted by the new report found that 1% of youth who received gender-affirming medications in the study re-identified with their assigned sex at birth.

In another study noted in the report, this one in the LGBT Health journal, 82.5% of those surveyed "reported familial pressure, social pressure, employment difficulty, inability to access care, and financial reasons" as the reason they presented themselves as their sex assigned at birth.