Author: Teni Gomez
Editor: Patrick Toh
Artist: Bella Marwick
In 2020, the NHS initiated the Cass Review, an independent assessment of the UK’s gender identity development services. The goal was to produce recommendations for enhancing children’s gender care, yet the final report, published in April 2024, has drawn extensive criticism from healthcare professionals and advocacy organisations. The report’s findings, which deviate markedly from internationally accepted standards of care as set by the World Professional Association for Transgender Health (WPATH), have been influential in policy shifts that greatly risk harming trans youth. This article critically examines key issues with the Cass Review, including serious methodological weaknesses, misguided medical recommendations, and a pervasive cisnormative bias that impacts its conclusions and recommendations.
Methodological Flaws of the York Reviews
The Cass Review’s conclusions are largely based on seven internal systematic reviews, called the York Reviews (YRs), supplemented by additional quantitative and qualitative studies. Systematic reviews require evaluation and summary of all studies relevant to a research question. However, an analysis conducted by Noone et al. using the ROBIS tool found significant bias and cherry-picking of studies in all seven YRs, undermining the reliability of the findings.
The York Reviews were expected to be guided by a so-called protocol document detailing eligibility criteria for study inclusion. However, ambiguities in this protocol, combined with inconsistencies in its application, rendered the YRs irreproducible. For instance, although the protocol called for the Mixed Methods Appraisal Tool (MMAT) to evaluate studies, three of the reviews instead used an adapted Newcastle-Ottawa Scale (NOS), which has faced substantial criticism as unsuitable for medical research. This shift in evaluation method led to the exclusion of 48% of relevant studies on puberty blockers and 36% of studies on hormone therapy.
A key reason for excluding these studies was the lack of blind control groups—a standard that is ethically and practically unattainable given the noticeable physical effects of puberty blockers and hormones. Insisting on such controls suggests deliberate cherry-picking of evidence to fit a predetermined narrative, ultimately compromising the report’s credibility.
Poorly Informed Medical Recommendations
One major consequence of the Cass Review was the NHS’s effective restriction on prescribing puberty blockers to minors outside of clinical trials, a decision implemented in March 2024. This recommendation to restrict puberty blockers for young people arose from narrow analysis and a distorted interpretation of evidence. McNamara et al. highlight that the widely accepted GRADE framework, typically used for evaluating healthcare recommendations, includes considerations of evidence quality, benefit-harm balance, patient values, and resource utilisation. The Cass Review prioritised the first criteria while largely ignoring the remaining three.
This restrictive approach to evidence evaluation led the Cass Review to deem only 2 of 103 papers on puberty blockers as “high quality.” Such extreme standards are not seen in other areas of medicine like anaesthesia, breast cancer, and stroke care, where evidence which does not meet the highest levels of methodological rigour are included. The disproportionate application of these criteria in trans healthcare suggests a selective, potentially punitive standard not applied in other fields.
Furthermore, while some trans youth were consulted for the review, their input was often dismissed, with recommendations ultimately diverging from their expressed needs. The review also largely overlooked the psychological and physical repercussions of denying treatment to trans youth, who may develop permanent, incongruent physical traits if denied puberty blockers. While purported treatment risks were discussed, the serious consequences of withholding care were downplayed, reflecting a skewed view of risk.
Cisnormative Bias and Lack of Expertise
There is significant evidence of cisnormative bias—the assumption that everyone is or should be cisgender, leading to transness being viewed as a problem—and a general lack of knowledge on basic trans healthcare within the research group.
This bias was evident in the composition of the research team. Experts in trans healthcare were deliberately excluded under the guise of reducing bias, an approach not paralleled in other medical or scientific fields where expertise is valued. Furthermore, in an environment where trans prejudice has doubled since 2019 and hate crimes have peaked, the research group’s composition raises concerns about impartiality, with no explicit exclusion of prejudiced members. Notably, Tilly Langton, an advocate of “gender exploratory therapy” (a modern form of conversion practice), was involved in designing the YR methodology.
Additionally, 32% of healthcare professionals interviewed for the report stated they “do not believe in the existence of trans children”, a view incompatible with providing informed, compassionate care. The review’s language choices further underscored this bias by referring to trans children as merely “gender-questioning”, a term that questions the permanence of their identities. Such framing contributes to the marginalisation and pathologization of trans youth.
The report’s conclusions are also undermined by a lack of understanding of fundamental aspects of trans healthcare. It incorrectly argued that puberty blockers are ineffective for alleviating gender dysphoria or body dissatisfaction, ignoring that these medications aim to prevent unwanted physical developments rather than alter current characteristics. The report cited stable mental health scores as a “failure,” when in reality, stability is a beneficial and desired outcome for trans youth undergoing puberty blockers.
Conclusion
The Cass Review, despite being promoted as an authoritative document, suffers from serious methodological and ethical flaws. Its selective evidence review, unrealistic study criteria, and underlying cisnormative bias have contributed to recommendations with harmful outcomes for trans youth. These recommendations have already influenced NHS policy, restricting access to puberty blockers and closing some gender services, placing vulnerable children at risk. Trans youth deserve informed, compassionate healthcare rooted in scientific understanding and respect for their identities, which the review sorely lacks.
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