The reviews searched over 12,000 references. They screened 547 full-text papers for inclusion. They included 17. That's a 96.9% exclusion rate at full text. 530 studies were relevant enough to survive initial screening, then rejected by the review criteria. 6/10 reviews found 0 included studies.
The reviews used to justify this excluded nearly 97% of all studies from inclusion in their analysis. This is an absolutely obscene hatchet job by the NHS specifically created to eliminate access to hormones for trans youth.
How? They split one clinical intervention, hormones for trans adolescents, into ten separate reviews. Not one review of feminising hormones. Not one review of masculinising hormones. Ten reviews, fragmented by exact pharmacological combination and by binary vs non-binary identity. The non-binary fragmentation is the most devastating. All 6 non-binary reviews found zero included studies. 0. The published literature doesnt routinely disaggregate nonbinary participants as a separate population. Demanding isolated NB outcomes guarantees finding nothing. That's what they found. The most consequential exclusion is the Dutch Protocol that has been the general standard of care for decades. The reviews excluded it from everything. The monotherapy reviews excluded Dutch Protocol studies because participants received GnRH analogues for puberty suppression before hormones. The combination-therapy reviews also excluded them, because GnRH analogues were initiated for puberty suppression rather than concurrently with hormones. Boogers et al 2022: "GnRH analogues used in the context of puberty suppression. Intervention out-of-scope." Klaver et al 2020: "GnRH analogues used in the context of puberty suppression. Intervention out-of-scope." Schagen et al 2020: Same. Klink et al 2015: Same. Hannema et al 2017: Same. It gets worse. They excluded Chen et al 2023, published in the New England Journal of Medicine. The largest NIH-funded prospective study of trans youth (n=315). Found that depression and anxiety decreased over two years of hormone therapy. The NEJM study is invisible to all ten reviews. They excluded Tordoff et al 2022, published in JAMA. Prospective cohort finding 60% lower odds of depression and 73% lower odds of suicidality. Excluded for the same reason: mixed transfeminine and transmasculine cohort. Olson-Kennedy et al 2025, 24-month follow-up, longitudinal, from the same NIH cohort. Excluded. Same reason. The 3 largest, best-funded prospective studies in the field. All excluded. All because they studied trans youth as a cohort rather than disaggregating by exact hormone regimen. They excluded Lavender et al 2023, a UK study, from the Tavistock's own Gender Identity Development Service. The closest thing to directly relevant NHS evidence. Excluded because GnRH analogues were used for puberty suppression. NHS England excluded its own clinical data. They excluded Butler et al 2022, data from NHS England's own paediatric endocrine clinics. 1,089 patients over 13 years. Excluded because GnRH analogues were used for puberty suppression. They excluded Taylor et al 2024, a systematic review that was part of the Cass Review. They excluded Baker et al 2021 (systematic review), Chew et al 2018 (systematic review, Pediatrics), Miroshnychenko et al 2025 (systematic review, Archives of Disease in Childhood). Systematic reviews were excluded because they examined hormones as they are actually prescribed. So what did the reviews actually find? "Very low certainty evidence" across all outcomes in all reviews. "No evidence was identified" 250 times across the combined document. But "no evidence meeting these extremely specific criteria" is not the same claim as "no evidence these treatments work." The first is a statement about a search strategy. The second is a clinical conclusion. The reviews conflate them. The policy initiating the ban depends on the conflation. And this is the anti-trans logic loop: 1. demand evidence 2. design reviews that cannot find evidence 3. cite absence of evidence as justification for withdrawing care 4. use withdrawal of care to prevent generation of new evidence. It's what the Reagan administration did to trans folks.