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Evidence-based objection to affirmative care

"Evidence-based gender-affirming care" is an empty creed. Systematic reviews have shown for years that the evidence base for puberty blockers and hormones in minors is thin: the Cass Review called it "an area of remarkably weak evidence" (source), and the 2020 NICE reviews rated the evidence on gender dysphoria, mental health and quality of life as "very low certainty" (source). Yet irreversible interventions in adolescents are defended as if the evidence were conclusive.

The GRADE outcomes

The Cass Review (2024) rested on a series of systematic reviews by the University of York: across all reviews, 237 papers (214 studies and 23 guidelines or position statements) were assessed (source). The review of puberty blockers found 50 studies, of which one was of high quality, 25 of moderate quality and 24 of low quality; the low-quality studies were left out of the synthesis (source). The 2020 NICE reviews, which used a modified GRADE, rated the evidence for puberty blockers (source) and for cross-sex hormones (source) on gender dysphoria, mental health and quality of life as "very low certainty". In the GRADE scale as the Cass Review describes it, "very low certainty" means that the true effect is probably markedly different from the estimated effect. In adult oncology, no committee would accept such evidence for mastectomy of healthy breasts. In children, however, they do. See Cass on puberty blockers and Cass on hormones .

National agencies, similar conclusions

The Swedish SBU (2022) concluded in its systematic review that the evidence for hormone treatment of children with gender dysphoria is insufficient (source); the British NICE (2020) rated the evidence as of very low certainty (see above). According to the Cass Review, the Finnish guideline of COHERE (2020) reached similar conclusions on the uncertainty of the evidence and proposed extreme caution with puberty blockers under the age of 18 (source). These are health authorities, not lobby groups or activists. The closure of Tavistock's gender clinic (GIDS) followed the interim report of the Cass Review, which found that a single national service was "not a safe or viable long-term option" (source). In the Netherlands, the Gezondheidsraad advised on 30 June 2026 not to reorganise care for young people, noting that studies mostly show the intended physical effects and some indications of mental improvement, but that effects on cognition and fertility and the long-term effects are insufficiently studied (source).

WPATH SOC-8 and its evidence reviews

The WPATH Standards of Care 8 (2022) note that, according to more recent guidelines, there may be compelling reasons to start hormone treatment before the age of 16, where the previous guidelines spoke of approximately 16 (source). WPATH commissioned evidence reviews from Johns Hopkins researchers; according to The BMJ (31 October 2024) those researchers wrote that the commissioning body tried to restrict their ability to publish, which WPATH denied (source). The WPATH Files (2024) of Environmental Progress conclude from internal messages that members know children and adolescents cannot oversee the lifelong consequences of treatment and that WPATH does not meet the standards of evidence-based medicine; that is the reading of Environmental Progress, and of the members contacted one confirmed their own statements while another disputed the interpretation (source). See WPATH conflicts of interest and the SOC versions .

What requires evidence-based training — and what is missing here

True evidence-based medicine requires (1) systematic review, (2) GRADE assessment, (3) harm-benefit analysis, (4) patient preferences under genuine informed consent. On the first two points the available reviews are clear about the limits: the systematic review underlying the Swedish SBU assessment found no randomised controlled trials, and the few longitudinal observational studies were hampered by small numbers and high attrition, so the long-term effects of hormone treatment on psychosocial health could not be evaluated (source). NICE found only small uncontrolled observational studies, with results of low to very low certainty (source). The Swedish guideline of 2022 also noted the lack of clear data on how often detransition or regret occurs in young adults (source).

No marker, no test, no evidence

The diagnosis of "gender dysphoria" relies entirely on self-reporting — there is no biological marker , no brain scan , no genetic substrate . On that basis, irreversible interventions are hard to justify as medicine. In her foreword, Hilary Cass writes that there are few other areas of healthcare where professionals are so afraid to openly discuss their views (source).