Cass Review

The Independent Review of Gender Identity Services for Children and Young People (commonly, the Cass Review) was commissioned in 2020 by NHS England and NHS Improvement and led by Hilary Cass, a retired consultant paediatrician and the former president of the Royal College of Paediatrics and Child Health. It dealt with gender services for children and young people, including those with gender dysphoria and those identifying as transgender.

The final report was published on 10 April 2024, and was endorsed by both the Conservative and Labour parties.

The review has been criticised by several transgender-related medical organisations, and a number of international medical organisations have expressed disagreement with some of its conclusions.

Background
The interim report of the Cass Review was published in March 2022. It said that the rise in referrals had led to the staff being overwhelmed, and recommended the creation of a network of regional hubs to provide care and support to young people. The report noted that the clinical approach used by the Gender Identity Development Service (GIDS) "has not been subjected to some of the usual control measures" typically applied with new treatments, and raised concerns about the lack of data collection by GIDS. While GIDS initially followed the Dutch protocol, the interim review said there were "significant differences" in the current NHS approach. Children with comorbidities did not receive adequate psychological support, endocrinologists administering puberty blockers did not attend multidisciplinary meetings nor did the frequency of meetings increase when adolescents received puberty blockers, all of which the Dutch Approach recommends.

The interim report further stated that GPs and other non-GIDS staff felt "under pressure to adopt an unquestioning affirmative approach" to children unsure of their gender, "overshadowing" other issues such as poor mental health. The Tavistock and Portman NHS Foundation Trust said "being respectful of someone's identity does not preclude exploration", and "We agree that support should be holistic, based on the best available evidence and that no assumptions should be made about the right outcome for any given young person."

The final report of the Cass Review was published on 10 April 2024. It included several systematic reviews of scientific literature carried out by University of York, encompassing the patient cohort, service pathways, international guidelines, social transitioning, puberty blockers and hormone treatments.

Methodology
The Cass Review commissioned several independent, peer-reviewed systematic reviews into different areas of healthcare for children and young people with gender identity issues, including gender dysphoria. The reviews were carried out by academics at the University of York's Centre for Reviews and Dissemination, one of three bodies funded by the National Institute for Health and Care Research (NIHR) to provide a systematic review service to the NHS. The topics covered by the systematic reviews were:
 * Characteristics of children and adolescents referred to specialist gender services
 * Impact of social transition in relation to gender for children and adolescents
 * Psychosocial support interventions for children and adolescents experiencing gender dysphoria or incongruence
 * Interventions to suppress puberty in adolescents experiencing gender dysphoria or incongruence (puberty blockers)
 * Masculinising and feminising hormone interventions for adolescents experiencing gender dysphoria or incongruence (cross-sex hormone therapy)
 * Care pathways of children and adolescents referred to specialist gender services
 * Clinical guidelines for children and adolescents experiencing gender dysphoria or incongruence

In the systematic reviews the report commissioned, tools such as the Mixed Methods Appraisal Tool and modified versions of the Newcastle–Ottawa scale were used to assess the quality of the studies available because no blind control studies - those usually thought of as having the highest quality - were available. The systematic reviews performed meta-analyses to ascertain the best evidence-based knowledge on their respective subjects to inform the report's findings and recommendations.

In its collection of evidence, the report also carried out qualitative and quantitative research into young people with gender dysphoria and their health outcomes, carried out listening sessions and focus groups with service users and parents, held meetings with advocacy groups, and gathered existing documented insights into the lived experiences of patients.

Lack of research
The report states on page 20 that “When the Review started, the evidence base, particularly in relation to the use of puberty blockers and masculinising / feminising hormones, had already been shown to be weak"; and that after the examination of over 100 pieces of potential evidence, that "there continues to be a lack of high-quality evidence in this area".

Increase in referrals
The report found no clear explanation for the rise in the number of children and adolescents with gender dysphoria, but stated there was broad agreement for attribution to a mix of biological and psychosocial factors. Suggested influences included a lower threshold for medical treatment, social media-related mental health consequences, abuse, access to information regarding gender dysphoria, struggles with emerging sexual orientation, and early exposure to online pornography. The report considered a rise in acceptance of transgender identities to be insufficient to explain the increase.

Social transition
A systematic review evaluated 11 studies assessing the outcomes of social transition in minors using a modified version of the Newcastle-Ottawa scale and considered 9 to be low quality and two to be moderate quality. The report stated that insufficient evidence was available to assess whether social transition in childhood has positive or negative effects on mental health, and that there was weak evidence for efficacy in adolescence. It also stated that sex of rearing seems to influence gender identity, and hypothesised that early social transition may change the way a child's gender identity develops.

The report classified social transition as an "active intervention". It also advised caution in approaching social transition, and stressed the need for clinical involvement in determining risks and benefits, saying that it is not a role that can be undertaken without appropriate clinical training.

Puberty blockers
The report stated that the evidence base and rationale for early puberty suppression remains unclear, with unknown effects on cognitive and psychosexual development. A systematic review examined 50 studies on the use of puberty blockers using a modified version of the Newcastle–Ottawa scale and considered only one to be of high quality, along with a further 25 being of moderate quality, and the remaining 24 being of low quality. The review concluded that the lack of evidence means no conclusions can be made regarding the impact on gender dysphoria and mental health, but did find evidence of bone health being compromised during treatment. The review disagreed with the idea of puberty blockers providing youth patients with "time to think", due to the finding that nearly all patients who went on blockers later decided to proceed on to hormone therapy. For birth-registered males the report states uncontroversially that blockers taken too early can make a later vaginoplasty more difficult due to insufficient penile growth, although blockers do prevent lower voice and facial hair.

Hormone therapy
The report stated that many unknowns remained for the use of hormone treatment among under-18s, despite longstanding use among transgender adults, with poor long-term follow-up data and outcome information on those starting younger. A systematic review evaluated 53 studies on transgender hormone therapy using a modified version of the Newcastle-Ottawa scale, and considered only one study to be of high quality, 33 moderate and 19 low quality. Overall, the review found some evidence that hormone treatment improves psychological outcomes after 12 months, but found insufficient/inconsistent evidence regarding physical risks and benefits. The review advised that there should be a 'clear clinical rationale' for the prescription of hormone therapy under 18 years of age.

Psychosocial intervention
A systematic review assessed ten studies on the efficacy of psychosocial support interventions in transgender minors using the Mixed Methods Appraisal Tool and considered only one to be of medium quality, with the remaining nine being of low quality. The review concluded that no robust conclusions can be made and more research is needed. The report said that the evidence for psychosocial intervention as opposed to hormonal was "as weak as research on endocrine treatment", but that the result of psychological treatment was "either benefit or no change".

Clinical pathways
The report stated that clinicians cannot be certain which children and young people will have an enduring trans identity in adulthood, and that for most, a medical pathway will not be the most appropriate. When a medical pathway is clinically indicated, wider mental health or psychosocial issues should also be addressed. Due to a lack of follow-up, the number of individuals who detransitioned after hormone treatment was unknown.

The Cass Review attempted to work with the Gender Identity Development Service and the NHS adult gender services to "fill some of the gaps in follow-up data for the approximately 9,000 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."

International guidelines
A systematic review assessed 23 regional, national and international guidelines covering key areas of practice, such as care principles, assessment methods and medical interventions. Most guidelines were stated to lack editorial independence and developmental rigour, and were nearly all influenced by the 2009 Endocrine Society guideline and the 2012 WPATH guideline, which were themselves closely linked. The Cass review questioned the guidelines' reliability, and concluded that no single international guideline regarding transgender care could be applied in its entirety to NHS England.

Conflicting clinical views
The report identified conflicting views among clinicians regarding appropriate treatment, with expectations of care sometimes deviating from clinical norms. It noted that disputes over language such as "exploratory" and "affirmative" approaches meant it was difficult to establish neutral terminology. Some clinicians feared working with gender-questioning young people. The report stated that some professionals were concerned about being accused of conversion practices, and were likewise concerned about legislation to ban conversion therapy. The report went on to say that many professionals were "overshadowed by an unhelpfully polarised debate around conversion practices".

Recommendations
The report made 32 recommendations covering areas including assessment of children and young people, diagnosis, psychological interventions, social transition, improving the evidence base underpinning medical and non-medical interventions, puberty blockers and hormone treatments, service improvements, education and training, clinical pathways, detransition and private provision.

Recommendations included:


 * The development of a regional network of centres, and continuity of care for 17-25-year-olds.
 * The use of standard psychological and pharmacological treatments for co-occurring conditions like anxiety and depression.
 * Individualised care plans, including mental health assessments and screening for neurodivergent conditions such as autism.
 * A designated medical practitioner who takes personal responsibility for the safety of children receiving care.
 * That children and families considering social transition should be seen as soon as possible by a relevant clinical professional.

Implementation
NHS England responded positively to the interim and final reports. they have implemented a number of measures. The Gender Identity Development Service (GIDS) at the Tavistock and Portman NHS Foundation Trust closed in March 2024. Two new services, located in the north west of England and in London, opened in April 2024, which are intended to be the first of up to eight regional services. These will follow a new service specification for the "assessment, diagnosis and treatment of children and young people presenting with gender incongruence". Puberty suppressing hormones are no longer routinely available in NHS youth gender services. New patients that have been assessed as possibly benefiting from them will be required to participate in a clinical trial that is being set up by the National Institute for Health and Care Research. A new board, chaired by Simon Wessely will encourage further research in the areas highlighted in the review as having a weak evidence base.

In May 2024, acting Health Secretary Victoria Atkins implemented a three month emergency ban on the prescription of puberty blockers by medical providers outside of the NHS, with violators risking up to two years in prison. In July 2024 her successor, Wes Streeting, declared that the ban would be made permanent.

Interim report in February 2022
The interim report, published in February 2022, stated that there were "gaps in the evidence" over the use of puberty blockers. A public consultation was held and a further review of evidence by NICE stated there was "not enough evidence to support the safety or clinical effectiveness of puberty suppressing hormones to make the treatment routinely available at this time." As a result, NHS England stopped prescribing them to children.

In April 2022, Health Secretary Sajid Javid told MPs that services in this area were too affirmative and narrow, and "bordering on ideological".

In November 2022, the World Professional Association for Transgender Health (WPATH), along with ASIAPATH, EPATH, PATHA, and USPATH issued a statement criticising the NHS England interim service specifications based on the interim report. It stated several points of contention with the report, including the pathologizing of gender diversity, the making of "outdated" assumptions regarding the nature of transgender individuals, "ignoring" of newer evidence regarding such matters, and making calls for an "unconscionable degree of medical and state intrusion" into everyday matters such as pronouns and clothing choice, as well as into access to gender-affirming care. It further noted that "the denial of gender-affirming treatment under the guise of 'exploratory therapy' is tantamount to 'conversion' or 'reparative' therapy under another name".

Reception among UK political parties
Prime Minister at the time Rishi Sunak said that the findings "shine a spotlight" on the need for a cautious approach to child and adolescent gender care. Wes Streeting, the shadow Health Secretary, welcomed the final report, saying that the report "must provide a watershed moment for the NHS's gender identity services" and committing the Labour Party to implementing the report's recommendations in full. Speaking to Sky News, Shadow Home Secretary Yvette Cooper stated that Labour welcomed the Cass Review and committed to implementing all of its recommendations.

The Scottish Government said it would "take the time to consider the findings". SNP politician Joanna Cherry called for an overhaul to services in Scotland for gender-questioning children, including screening out neurodivergent patients, and an end to the use of puberty blockers. Humza Yousaf, First Minister of Scotland and SNP leader at the time of the final report's release, stated that while the Scottish government would discuss the Cass Review with health authorities, it would leave its implementation up to clinicians. In July 2024 a multi-disciplinary team commissioned by the Chief Medical Officer to assess the recommendations of the Cass Review advised the Scottish Government to pause puberty blockers pending further research.

Response from NHS England and NHS Scotland
In response to the report, the NHS England National Director of Specialised Commissioning John Stewart sent a letter to Cass stating that it would review the use of gender-affirming transgender hormone therapy in adults in a similar manner as was done for puberty blockers in the Cass Review.

On 18 April 2024, NHS Scotland announced that it had paused prescribing puberty blockers to children referred by its specialist gender clinic.

Response from other health bodies
The British Psychological Society commended the review as "thorough and sensitive", in light of the complex and controversial nature of the subject.

The Royal College of Psychiatrists, the main professional organisation of British psychiatrists, welcomed the report and strongly agreed with its recommendations. They supported the emphasis on a holistic and person-centred approach and research to improve the evidence basis for treatment protocols. They noted that some of its trans members, and the wider trans community, had concerns about availability of treatments while awaiting research, along with differences of opinion about social transition or the possible explanations for the increase in referrals.

The Royal College of Paediatrics and Child Health, the professional body for British paediatricians, thanked Cass and her team for their "massive undertaking". They noted that data collected had identified a lack of confidence by paediatricians and GPs to support this patient group, which the RCPCH would address by developing new training.

The American Academy of Pediatrics and the Endocrine Society both responded to the report by reaffirming their support for gender-affirming care for minors and saying that their current policies supporting such treatments are "grounded in evidence and science".

The Canadian Pediatric Society responded to the report by saying "Current evidence shows puberty blockers to be safe when used appropriately, and they remain an option to be considered within a wider view of the patient's mental and psychosocial health."

The Amsterdam University Medical Center put out a statement saying that while it agrees with the goals of reducing wait times and improving research, it disagrees that the research-base for puberty blockers is insufficient, asserting that puberty blockers have been used in trans care for decades.

The Royal Australian and New Zealand College of Psychiatrists rejected calls for an inquiry into trans healthcare following the release of the Cass Review. They characterised the Cass Review as one review among several in the field. They emphasised that, "assessment and treatment should be patient centred, evidence-informed and responsive to and supportive of the child or young person’s needs and that psychiatrists have a responsibility to counter stigma and discrimination directed towards trans and gender diverse people."

Response from transgender specialist medical bodies
The World Professional Association for Transgender Health released an email statement saying that the report "is rooted in the false premise that non-medical alternatives to care will result in less adolescent distress" and further criticised recommendations which "severely restrict access to physical healthcare, and focus almost exclusively on mental healthcare for a population which the World Health Organization does not regard as inherently mentally ill". An official statement expanded on these concerns, criticising Cass's "negligible prior knowledge or clinical experience", asserting that "the (research and consensus-based) evidence is such to recommend that providing medical treatment including puberty-blocking medication and hormone therapy is helpful and often life-saving", and questioning the provision of puberty blockers only in the context of a research protocol: "The use of a randomized blinded control group, which would lead to the highest quality of evidence, is ethically not feasible."

The Professional Association for Transgender Health Aotearoa (PATHA), a New Zealand professional organisation, stated that the Cass Review made "harmful recommendations" and was not in line with international consensus, and that "Restricting access to social transition is restricting gender expression, a natural part of human diversity." They further stated that several people involved in the review "previously advocated for bans on gender-affirming care in the United States, and have promoted non-affirming 'gender exploratory therapy', which is considered a conversion practice." A joint statement by Equality Australia signed by the Australian Professional Association for Trans Health (AusPATH) and PATHA among others stated the review "downplays the risk of denying treatment to young people with gender dysphoria and limits their options by placing restrictions on their access to care".

Assorted responses
Amnesty International criticised "sensationalised coverage" of the review, stating "This review is being weaponised by people who revel in spreading disinformation and myths about healthcare for trans young people." Trans youth charity Mermaids and the LGBTQIA+ charity Stonewall endorsed some of the report's recommendations, such as expanding service provisions with the new regional hubs, but raised concerns the review's recommendations may lead to barriers for transgender youth in accessing care.

Gender-critical organisations including Sex Matters and Genspect welcomed the report. Stella O'Malley of Genspect expressed concern that if a conversion therapy ban were to criminalise any exploration into why a child identifies as trans, it "would ban the very therapy that Cass is saying should be prioritised".

The British Equality and Human Rights Commission described it as a "vital milestone" and called for all service providers to fully implement the recommendations of the review. The report was praised by some academics in the UK, who agreed with its findings stating a lack of evidence; while others both in the UK and internationally  disagreed with the report's methodology and findings. It was praised by author J.K. Rowling and United Nations Special Rapporteur Reem Alsalem.

The Integrity Project at Yale Law School released a report critiquing the Cass Review, accusing it of having "serious flaws." The report, co-authored by a group of eight legal scholars and medical researchers, argues that the Cass report "levies unsupported assertions about gender identity, gender dysphoria, standard practices, and safety of gender-affirming medical treatments, and it repeats claims that have been disproved by sound evidence" and that "is not an authoritative guideline or standard of care, nor is it an accurate restatement of the available medical evidence on the treatment of gender dysphoria."

Hilary Cass's response
In the week after the release of the final report, Cass described receiving abusive emails and was given security advice to avoid public transport. She also said that "disinformation" had frequently been spread online about the report. Cass stated "if you deliberately try to undermine a report that has looked at the evidence of children's healthcare, then that's unforgivable. You are putting children at risk by doing that." There were widespread false claims from critics of the report that it had dismissed 98% of the studies it collected and all studies which were not double-blind experiments. Cass described these claims as being "completely incorrect". Although only 2% of the papers collected were considered to be of high quality, 60% of the papers, including those considered to be of moderate quality, were considered in the report's evidence synthesis. She criticised Labour MP Dawn Butler for repeating, during a debate in the House of Commons, incorrect claims that the review had dismissed more than 100 studies. After talking with Cass, Butler subsequently used a point of order to admit her mistake and correct the record in Parliament, stating the figure came from a briefing she had received from Stonewall.

In an interview with The New York Times in May 2024, Cass expressed concern that her review was being weaponized to suggest that trans people do not exist, saying "that's really disappointing to me that that happens, because that's absolutely not what we're saying." She also clarified that her review was not about defining what trans means or rolling back health care, stating "There are young people who absolutely benefit from a medical pathway, and we need to make sure that those young people have access — under a research protocol, because we need to improve the research — but not assume that that's the right pathway for everyone."

In an interview with WBUR-FM in May 2024, Cass responded to WPATH's criticism about prioritising non-medical care, saying the review did not take a position about which is best. Cass hoped that "every young person who walks through the door should be included in some kind of proper research protocol" and for those "where there is a clear, clinical view" that the medical pathway is best will still receive that, and be followed up to eliminate the "black hole of not knowing what's best". On the allegation that the review was predicated on the belief that a trans outcome for a child was the worst outcome, Cass emphasised that a medical pathway, with lifetime implications and treatment, required caution but "it's really important to say that a cis outcome and a trans outcome have equal value".