The Science on Gender-Affirming Care: What the Evidence Actually Shows

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The proposed federal rule banning gender-affirming care for youth at Medicare and Medicaid participating hospitals rests on a specific claim: that the scientific evidence supporting this care is inadequate. Public comments on this rule are now closed, but I want to share my concerns and ensure that accurate information about this topic remains available. It’s a claim worth examining carefully—because when you look at what the research actually says, and when you look at the methodology behind the review the government relied upon, a very different picture emerges.

Every Reputable Medical Organization Disagrees With This Rule

Let’s start with the broadest measure of scientific consensus. Gender-affirming care for appropriately evaluated youth is endorsed by:

• The American Academy of Pediatrics (67,000 pediatricians)
• The American Medical Association (250,000+ physicians)
• The American Psychological Association (157,000 psychologists)
• The American Academy of Child and Adolescent Psychiatry
• The Endocrine Society (18,000+ endocrinologists)
• The Pediatric Endocrine Society
• The American Academy of Family Physicians
• The American Psychiatric Association
• The World Professional Association for Transgender Health (WPATH)

These organizations arrived at their positions through rigorous evidence review processes. They represent the considered judgment of American medicine. The proposed rule dismisses this consensus wholesale—without engaging their evidence, without offering a credible counter-analysis, and without acknowledging that this is an extraordinary step.

What the Research Shows

The research literature on gender-affirming care outcomes is more robust than critics claim. Here is a small sample of what peer-reviewed studies have found:

Mental health improvements are significant and measurable. A prospective study published in JAMA Network Open found that transgender and nonbinary youth receiving gender-affirming care showed a 60% reduction in depression and a 73% reduction in suicidality over 12 months compared to those not receiving such care .

These improvements are sustained over time. A four-site, NIH-funded prospective study published in the New England Journal of Medicine followed 315 transgender and nonbinary youth for two years after initiating gender-affirming hormones . The study found significant improvements in appearance congruence and psychosocial functioning—including reduced depression and increased positive affect and life satisfaction—across the follow-up period. The authors concluded that these findings support gender-affirming hormones as an effective treatment for transgender and nonbinary youth.

Regret rates are exceptionally low — lower than for comparable procedures in cisgender patients. A study published in JAMA Surgery found that fewer than 1% of transgender individuals who received gender-affirming surgery reported surgical regret . For context, cisgender women undergoing risk-reducing mastectomy report regret rates between 5% and 14%. The authors attribute these outcomes to the careful, multidisciplinary evaluation required before surgery—the same guidelines the proposed rule would effectively end.

Longitudinal data on adolescents show high satisfaction years later. A landmark study published in JAMA Pediatrics tracked 220 youth who received puberty blockers and/or hormones, with follow-up occurring a mean of nearly five years after starting blockers . An overwhelming 97% of participants continued gender-affirming medical care at the study’s endpoint. Only 4% expressed any regret about blockers or hormones—and of those, half were continuing their care anyway.

Satisfaction among those who accessed care as adolescents is high. A 2024 study in the Journal of Adolescent Health surveyed individuals who first accessed gender-affirming care as adolescents. At follow-up (average age 18.6 years), 88% reported satisfaction and 86.7% reported confidence associated with their care. Only 2% reported regret—and just one participant (0.7% of hormone users) wished they had never started . The authors note that when discontinuation occurred, it was overwhelmingly driven by external factors—insurance barriers, financial hardship, lack of support—not regret about gender identity.

The Government’s Evidence Base Has a Serious Problem

The proposed rule relies heavily on a Department of Health and Human Services review that was produced in 90 days, under a politically motivated executive order, by anonymous authors, without peer review. No credible medical organization would base treatment guidelines on such a document.

More troubling is what that document is itself based on: the Cass Report, a review commissioned in the United Kingdom that has since been subjected to withering methodological critique in peer-reviewed scientific literature.

A comprehensive analysis published in BMC Medical Research Methodology evaluated all seven systematic reviews that were commissioned to inform the Cass Report . The findings are damning. Using the validated Risk of Bias in Systematic Reviews (ROBIS) tool, the researchers found that all seven reviews in the Cass Report were at high risk of bias. The problems included:

Unexplained deviations from the pre-registered protocol. Six of seven reviews excluded non-English sources and grey literature despite the protocol stating these would be included. All seven reviews excluded qualitative research, despite it being specified in the protocol and despite several research questions being ideally suited to qualitative methods. None of these exclusions were explained or justified.

Inappropriate quality assessment methods. Multiple reviews used an adapted Newcastle-Ottawa Scale (NOS) instead of the tool specified in the protocol—again, without explanation. In a particularly striking finding, one review cited a paper by Stang and colleagues to justify using the NOS, despite that paper explicitly arguing against using it for systematic reviews. Based on this inappropriate methodology, 48% of studies were excluded from the puberty blocker review and 36% from the hormone therapy review.

Misrepresentation of findings. In the hormone therapy review, the authors concluded that no conclusions could be drawn about mental health benefits—despite their own data showing five studies on 415 transgender youth demonstrating positive psychological outcomes, with no study showing consistent harm. The methodological critique characterizes this as “vote-counting rather than appropriate evidence synthesis.”

The concerns raised in this peer-reviewed analysis were serious enough that the British Medical Association took the extraordinary step of commissioning an independent evaluation of the Cass Report, explicitly citing the Noone et al. critique . That is an unprecedented response from a major national medical organization, and it reflects the depth of legitimate scientific concern about the Cass Report’s validity.

“Low-Certainty Evidence” Does Not Mean “Harmful”

One rhetorical move in the proposed rule deserves specific attention: the claim that because some evidence is of “low certainty,” the treatments should be banned. This fundamentally misrepresents how evidence-based medicine works.

Low-certainty evidence is common in pediatric medicine. Most pediatric drug dosing guidelines are based on extrapolations from adult data. Numerous established pediatric interventions have limited randomized controlled trial evidence, because running such trials on children is often ethically and practically impossible. A study of prescribing patterns at major US pediatric hospitals found that roughly 1 in 4 medications is prescribed off-label, meaning without FDA-approved labeling for that patient’s age group . The appropriate response to low-certainty evidence is informed consent (AMA, APA) and shared decision-making (AMA, APA), not government prohibition.

If CMS applied this evidentiary standard consistently, it would need to prohibit wide swaths of standard pediatric care. It does not. The standard is being applied selectively, to one group of patients, for reasons that are political rather than scientific.

Next in this series: The real-world harms this rule would cause, and what better alternatives look like.

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