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Correcting the homework 

Updated: Apr 17

New Zealand transgender lobby groups react emotively to the final Cass Review report 


April 12th 2024


Please refer to our media release - Speak Up for Women welcome the findings of the Cass Review for more information on The Cass Review.


Transgender lobby groups react to Cass Review


“Remarkably weak evidence”

“limited understanding”

“extreme caution”


These are some of the warnings sounded by Dr Hilary Cass in her landmark 388 page final report, titled Independent Review of gender identity services for children and young people that was published on 9 April 2024.


The report contains 263 pages of evidence from around the world and twelve appendices.  


Instead of welcoming this comprehensive review that was four years in the making and included a specially-commissioned systematic review by the University of York, trans lobby groups in New Zealand (PATHA, InsideOUT) have immediately denounced it.  


Here are some of their unsubstantiated claims, rebutted by words quoted from the Cass Report (CR).  


PATHA: The final Cass Review did not include trans or non-binary experts or clinicians experienced in providing gender affirming care in its decision-making, conclusions, or findings. 


  • In addition to formal research, an extensive programme of engagement has informed the  Review. A mixed-methods approach was taken that prioritised input from people with  relevant lived experience and organisations working with LGBTQ+ youth or children and  young people generally, and clinicians and other professionals with responsibility for  providing care and support to children and young people within specialist gender  services and beyond. (CR, p26)


PATHA: It’s shocking to see such a significant inquiry into transgender health completely disregard the voices of transgender experts. 


  • I have spoken to a very wide range of clinicians and academics. Clinicians who have spent many years working in gender clinics have drawn very different conclusions from  their clinical experience about the best way to support young people with gender-related  distress. Some feel strongly that a majority of those presenting to gender services will go  on to have a long-term trans identity and should be supported to access a medical  pathway at an early stage. Others feel that we are medicalising children and young  people whose multiple other difficulties are manifesting through gender confusion and  gender-related distress. (CR, Foreword)

  • To scrutinise the existing evidence the Review commissioned a robust and independent  evidence review and research programme from the University of York to inform its  recommendations and remained cautious in its advice whilst awaiting the findings. The  University of York’s programme of work has shown that there continues to be a lack of  high-quality evidence in this area and disappointingly, as will become clear in this report, attempts to improve the evidence base have been thwarted by a lack of  cooperation from the adult gender services. (CR, p20)

  • A strand of research commissioned by the Review was a quantitative data linkage study.  The aim of this study was to fill some of the gaps in follow-up data for the approximately  9,000 young people who have been through GIDS. This would help to develop a stronger  evidence base about the types of support and interventions received and longer-term outcomes. This required cooperation of GIDS and the NHS adult gender services. 92. In January 2024, the Review received a letter from NHS England stating that, despite efforts to encourage the participation of the NHS gender clinics, the necessary cooperation had not been forthcoming. (CR, p33)


PATHA: The lived experience and knowledge of our community members and clinicians does not make them biased - it means they’re the experts in this care. 


  • There remains diversity of opinion as to how best to treat these children and young people. The evidence is weak and clinicians have told us they are unable to determine  with any certainty which children and young people will go on to have an enduring trans  identity. (CR, p22)

  • The adoption of a medical treatment with uncertain risks, based on an unpublished trial  that did not demonstrate clear benefit, is a departure from normal clinical practice. (CR, p73)

  • Given the lack of evidence-based guidelines, it is imperative that staff working within NHS gender services are cognisant of the limitations in relation to the evidence base and fully understand the knowns and the unknowns. (CR, p28)

  • The research programme, led by the University of York, comprised appraisal of the published evidence and guidelines, an international survey and quantitative and qualitative research. A Clinical Expert Group (CEG) was established by the Review to help interpret the findings. (CR, p26)


PATHA: This review ignores the consensus of major medical bodies around the world and lacks relevance in an Aotearoa context. 


  • It often takes many years before strongly positive research findings are incorporated into  practice… Quite the reverse happened in the field of gender care for children. Based on  a single Dutch study, which suggested that puberty blockers may improve psychological  wellbeing for a narrowly defined group of children with gender incongruence, the  practice spread at pace to other countries. This was closely followed by a greater  readiness to start masculinising/feminising hormones in midteens, and the extension of  this approach to a wider group of adolescents who would not have met the inclusion  criteria for the original Dutch study. (CR, Foreword)

  • The World Professional Association of Transgender Healthcare (WPATH) has been highly  influential in directing international practice, although its guidelines were found by the  University of York appraisal process to lack developmental rigour. Early versions of two  international guidelines - the Endocrine Society 2009 and WPATH 7 - influenced nearly  all the other guidelines, except for the recent Nordic guidelines. (CR, p28)

  • These two guidelines are also closely interlinked, with WPATH adopting Endocrine Society recommendations, and acting as a co-sponsor and providing input to drafts of  the Endocrine Society guideline. WPATH 8 cited many of the other national and regional  guidelines to support some of its recommendations, despite these guidelines having  been considerably influenced by WPATH 7. (CR, p130)

  • The circularity of this approach may explain why there has been an apparent consensus  on key areas of practice despite the evidence being poor. (CR, p130)

  • WPATH commissioned a systematic review to underpin version 8, an approach it had not  undertaken for WPATH 7. This systematic review (Baker et al., 2021) found that “hormone therapy was associated with increased quality of life, decreased depression,  and decreased anxiety”. However, “certainty in this conclusion is limited by high risk of  bias in study designs, small sample sizes, and confounding with other interventions”. (CR, p31)

PATHA: The report published today again shows how the UK is an outlier in this field, and that our practice in Aotearoa aligns with other countries such as Australia and Canada. 


  • The findings raise questions about the quality of currently available guidelines. Most guidelines have not followed the international standards for guideline development, and  because of this the research team could only recommend two guidelines for practice - the Finnish guideline published in 2020 and the Swedish guideline published in 2022.  However, even these guidelines lack clear recommendations regarding certain aspects  of practice and would be of benefit if they provided more detailed guidance on how to  implement recommendations. (CR, p27-28) [NB The guidelines for NZ were included in the review. See p129 &135.]

  • For many of the guidelines it was difficult to detect what evidence had been reviewed and how this informed development of the recommendations. For example, most of the guidelines described insufficient evidence about the risks and benefits of medical treatment in adolescents, particularly in relation to long-term outcomes. Despite this, many then went on to cite this same evidence to recommend medical treatments. Alternatively, they referred to other guidelines that recommend medical treatments as their basis for making the same recommendations. Early versions of two international  guidelines, the Endocrine Society 2009 and World Professional Association for  Transgender Healthcare (WPATH) 7 guidelines influenced nearly all the other guidelines. (CR, p130)

PATHA: While we certainly look forward to more longitudinal research, the evidence in support of gender affirming care is clear, and we’re disappointed to see this review discard so much robust work from researchers around the world.  


  • Preliminary results from the [GIDS] early intervention study in 2015-2016 did not demonstrate benefit. The results of the study were not formally published until 2020, at  which time it showed there was a lack of any positive measurable outcomes. Despite  this, from 2014 puberty blockers moved from a research-only protocol to being available  in routine clinical practice and were given to a broader group of patients who would not  have met the inclusion criteria of the original protocol. The adoption of a treatment with  uncertain benefits without further scrutiny is a significant departure from established practice. This, in combination with the long delay in publication of the results of the study, has had significant consequences in terms of patient expectations of intended  benefits and demand for treatment. (CR, p25)

PATHA: When multiple observational studies produce similar findings, the cumulative evidence becomes compelling. 


  • There are many reports that puberty blockers are beneficial in reducing mental distress  and improving the wellbeing of children and young people with gender dysphoria, but as  demonstrated by the systematic review the quality of these studies is poor. (CR, p179)

  • Only the Swedish and Finnish guidelines differed by linking the lack of robust evidence  about medical treatments to a recommendation that treatments should be provided  under a research framework or within a research clinic. They are also the only guidelines  that have been informed by an ethical review conducted as part of the guideline  development. However, these guidelines like others lack clear recommendations  regarding certain aspects of practice and would benefit from more detailed guidance  regarding implementation of recommendations. (CR, p130)

  • A significant weakness of the studies evaluating psychological or psychosocial function  was the short follow-up interval, with many following-up for less than 1 year, and a  smaller number for up to 3 years. (CR p184)

InsideOUT: The Cass Review is a biased, unethical, methodologically flawed and politically motivated review… 


  • This is an area of remarkably weak evidence, and yet results of studies are exaggerated  or misrepresented by people on all sides of the debate to support their viewpoint. The  reality is that we have no good evidence on the long-term outcomes of interventions to  manage gender related distress. (CR, Foreword)

  • Throughout the course of the Review, it has been evident that there has been a failure to reliably collect even the most basic data and information in a consistent and comprehensive manner; data have often not been shared, or have been unavailable. This has led to challenges in understanding the patient cohort, referral data and outcomes, all of which have hindered the work of the Review. More importantly, this has  been to the detriment of young people and their families being able to make informed  decisions. (CR, p214)

  • I would also like to share some thoughts with all my clinical colleagues. We have to start  from the understanding that this group of children and young people are just that;  children and young people first and foremost, not individuals solely defined by their  gender incongruence or gender-related distress. We have to cut through the noise and  polarisation to recognise that they need the same standards of high-quality care to meet  their needs as any other child or young person. (CR, Foreword)


InsideOUT: The review justifies cherry-picking data by complaining about a lack of ‘high quality’ evidence in the research literature. But the ‘high quality’ evidence they’re talking  about is actually a specific kind of research – usually ‘double blind’ randomised trial (RCTs) where one group gets medication and the other gets a placebo.


  • It is often the case that when an intervention is given outside a randomised control trial  (RCT), a large treatment effect is seen, which sometimes disappears when an RCT is conducted. This is especially the case when there is a strong belief that the treatment is effective. The fact that only very modest and inconsistent results were seen in relation to improvements in mental health, even in the studies that reported some psychological  benefits of treatment with puberty blockers, makes it all the more important to assess  whether other treatments may have a greater effect on the distress that young people with gender dysphoria are suffering during puberty. (CR, p177)

  • 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. Identification of the core approach and outcomes for these interventions would ensure they are addressing  key clinical goals, attending to the needs of children and families as well as supporting  future aggregation of evidence. (CR p154)

InsideOUT: Requiring a different standard of research for one population in order to justify restricting their access to healthcare is discrimination.  


  • Firstly, you [Gender distressed children and young people] must have the same standards of care as everyone else in the NHS, and that means basing treatments on good evidence.

  • I have been disappointed by the lack of evidence on the long-term impact of taking hormones from an early age; research has let us all down, most importantly you. (CR, Foreword)

  • There are different issues involved in considering gender care for children and young people than for adults. Children and young people are on a developmental trajectory that continues to their mid-20s and this needs to be considered when thinking about the determinants of gender incongruence. An understanding of brain development and  the usual tasks of adolescence is essential in understanding how development of gender identity relates to the other aspects of adolescent development. (CR, p27)

  • However, there are clearly lessons to be learned by everyone in relation to how and why the care of these children and young people came to deviate from usual NHS practice, how clinical practice became disconnected from the clinical evidence base, and why warning signs that the service delivery model was struggling to meet demand were not  acted on sooner. (CR, p74)

PATHA: The Review’s recommendations include restricting access to both social transition and gender affirming hormone therapy… 


  • The information above demonstrates that there is no clear evidence that social transition in childhood has positive or negative mental health outcomes. There is relatively weak evidence for any effect in adolescence. However, sex of rearing seems to have some influence on eventual gender outcome, and it is possible that social transition in childhood may change the trajectory of gender identity development for children with early gender incongruence. For this reason, a more cautious approach needs to be taken for children than for adolescents. (CR, p164)

  • Parents should be encouraged to seek clinical help and advice in deciding how to support a child with gender incongruence and should be prioritised on the waiting list for  early consultation on this issue. Clinical involvement in the decision-making process  should include advising on the risks and benefits of social transition as a planned  intervention, referencing best available evidence. This is not a role that can be taken by staff without appropriate clinical training. (CR, p164)

  • The clinician should help families to recognise normal developmental variation in gender role behaviour and expression. Avoiding premature decisions and considering partial rather than full transitioning can be a way of ensuring flexibility and keeping  options open until the developmental trajectory becomes clear. (CR, p32)


InsideOUT: Suggesting clinical approval for things like changing your name, pronouns, or changing your wardrobe.  


  • We do not know the ‘sweet spot’ when someone becomes settled in their sense of self,  nor which people are most likely to benefit from medical transition. When making life changing decisions, what is the correct balance between keeping options as flexible and  open as possible as you move into adulthood, and responding to how you feel right  now? (CR, Foreword)

  • The current evidence base suggests that children who present with gender incongruence at a young age are most likely to desist before puberty, although for a small number the incongruence will persist. Parents and families need support and advice about how best to support their children in a balanced and nonjudgemental way.  Helping parents and families to ensure that options remain open and flexible for the child, whilst ensuring that the child is able to function well in school and socially is an important aspect of care provision and there should be no lower age limit for accessing  such help and support. (CR, p41)

  • It is not possible to attribute causality in either direction from the findings in these studies. This means it is not known whether the children who persisted were those with the most intense incongruence and hence more likely to socially transition, or whether  social transition solidified the gender incongruence. (CR, p163)


InsideOUT: These recommendations violate the human rights and bodily autonomy of trans young people.  


  • A further concern, already shared with NHS England (July 2022) (Appendix 6), is that adolescent sex hormone surges may trigger the opening of a critical period for experience dependent rewiring of neural circuits underlying executive function (i.e. maturation of the part of the brain concerned with planning, decision making and judgement). If this is the case, brain maturation may be temporarily or permanently disrupted by the use of puberty blockers, which could have a significant impact on the young person’s ability to make complex risk-laden decisions, as well as having possible longer term neuropsychological consequences. (CR, p178)

  • Blocking this experience means that young people have to understand their identity and  sexuality based only on their discomfort about puberty and a sense of their gender identity developed at an early stage of the pubertal process. Therefore, there is no way of knowing whether the normal trajectory of the sexual and gender identity may be permanently altered. (CR, p178)

  • Once on puberty blockers, they will enter a period when peers are developing physically and sexually whilst they will not be, and they may be experiencing the side effects of the blocker. There are no good studies on the psychological, psychosexual and  developmental impact of this period of divergence from peers. (CR, p196)

  • For the more recently presenting population of predominantly birth-registered females who develop gender dysphoria in early to mid-puberty, there is even less understanding of what in medical terms is called the ‘natural history’ of their gender dysphoria (that is,  what would happen without medical intervention). Because an intervention intended for one group of young people (predominantly pre pubertal birth-registered males) has been given to a different group, it is hard to know what percentage of these young people  might have resolved their gender-related distress in a variety of other ways. (CR, p177-8)

Dame Sue Bagshaw: "Because most kids know what they want, most kids know who they are. And that's confirmed with time, so they do carry on with the hormones.” 


  • Although young people often express a sense of urgency in their wish to access medical  treatments, based on personal experience some young adults have suggested that  taking time to explore options is preferable. The option to provide   masculinising/feminising hormones from the age of 16 is available, but the Review would recommend an extremely cautious clinical approach and a strong clinical rationale for providing hormones before the age of 18. This would keep options open during this important developmental window, allowing time for management of any co occurring conditions, building of resilience, and fertility preservation, if required. (CR, p34)

  • “I just wanted to get my bloody hormones, that was what I was there for, that’s what I wanted, that would’ve been my therapy, all my distress was related to needing to get on hormones and I was expressing this, I had a trans history, I was clearly aware of what I wanted and what care was on offer.” (CR, p166)

  • The early intervention study results were not published in preprint until December 2020  (Carmichael et al., 2021). There were no statistically significant changes reported in gender dysphoria or mental health outcome measures whilst on puberty blockers, and 98% proceeded to masculinising or feminising hormones. (CR, p71)

  • A subsequent re-analysis of the early intervention study (McPherson & Freedman, 2023), using original anonymised data from the study, took account of the direction of change in mental health outcomes for individual young people rather than just reporting group means. This secondary analysis found that 37-70% experience no reliable change in  distress across time points, 15-34% deteriorate and 9-29% reliably improve. (CR, p71)

PATHA: [A number of people involved in the review…] have promoted non-affirming ‘gender  exploratory therapy’, which is considered a conversion practice.  


  • In addition to treating co-existing conditions, the focus on the use of puberty blockers  for managing gender-related distress has overshadowed the possibility that other  evidence-based treatments may be more effective. The intent of psychosocial intervention is not to change the person’s perception of who they are, but to work with  them to explore their concerns and experiences and help alleviate their distress regardless of whether or not the young person subsequently proceeds on a medical pathway. (CR, p31)

  • It is harmful to equate this approach to conversion therapy as it may prevent young people from getting the emotional support they deserve. (CR, p150)

InsideOUT: We cannot disregard the fact that the overwhelming majority of existing clinical research supports a trans affirmation model of social and medical transition.  


  • The systematic review undertaken by the University of York found multiple studies demonstrating that puberty blockers exert their intended effect in suppressing puberty,  and also that bone density is compromised during puberty suppression. However, no  changes in gender dysphoria or body satisfaction were demonstrated. There was  insufficient/inconsistent evidence about the effects of puberty suppression on psychological or psychosocial wellbeing, cognitive development, cardio-metabolic risk or fertility. Moreover, given that the vast majority of young people started on puberty blockers proceed from puberty blockers to masculinising/ feminising hormones, there is no evidence that puberty blockers buy time to think, and some concern that they may change the trajectory of psychosexual and gender identity development. (CR, p32)

  • The Review’s letter to NHS England (July 2023) advised that because puberty blockers only have clearly defined benefits in quite narrow circumstances, and because of the  potential risks to neurocognitive development, psychosexual development and longer term bone health, they should only be offered under a research protocol. (CR, p32)

InsideOUT: Our informed consent model requires clinicians to have robust conversations about the benefits and potential risks of gender affirming care, ensuring that trans people and their whānau have all the information they need to make informed decisions.  


  • The gaps in the evidence base regarding all aspects of gender care for children and young people have been highlighted, from epidemiology through to assessment, diagnosis and intervention. It is troubling that so little is known about this cohort and their outcomes. An ongoing programme of work is required if the new casemix of children and young people and their needs are to be fully understood, as well as the short- medium- and longer-term impacts of all clinical interventions. (CR, p40)

  • The option to provide masculinising/ feminising hormones from age 16 is available, but  the Review would recommend an extremely cautious clinical approach. There should  be a clear clinical rationale for providing hormones at this stage rather than waiting until an individual reaches 18. This would keep options open during this important developmental window, allowing time for management of any cooccurring conditions, building of resilience and fertility preservation, if required. (CR, p196)


InsideOUT: We categorically reject any calls to restrict gender affirming care in Aotearoa.  


  • Too often this cohort are considered a homogenous group for whom there is a single driving cause and an optimum treatment approach, but this is an over-simplification of  the situation. Being gender-questioning or having a trans identity means different things to different people. Among those being referred to children and young people’s gender  services, some may benefit from medical intervention and some may not. The clinical approach must reflect this. (CR, p27)

  • One of the problems that has been exposed is the governance of innovative clinical practice. Whilst care cannot improve without innovation, good clinical governance should require collection of data and evidence with appropriate scrutiny to prevent the  incremental creep of new practices without adequate oversight. (CR, p74)

  • Innovation is important if medicine is to move forward, but there must be a proportionate level of monitoring, oversight and regulation that does not stifle progress,  but prevents creep of unproven approaches into clinical practice. Innovation must draw from and contribute to the evidence base. (CR, p45)


Contrary to the emotive claims of trans lobby groups, The Cass Report is an internationally significant, landmark report, characterised by rigorous and empathetic evidence-based recommendations.  

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