Several states have introduced bills that would prohibit certain physical procedures that alter the normal development or body of a child or adolescent for the purpose of facilitating a “gender transition.” These laws (sometimes called “Vulnerable Child Protection Acts”) would ban the use of puberty-blocking drugs, cross-sex hormones, or gender reassignment surgery in minors.

One of the arguments raised by opponents is that these procedures should not be restricted because they represent a standard of care that is “evidence-based.” “Evidence-based” is something of a buzzword in medicine, indicating that medical practices should not just be based on opinion (even “expert” opinion), but on sound scientific research.

But just how good is the “evidence” cited in support of gender transition procedures—especially for minors?

The Endocrine Society’s Influential Guidelines

One of the most recent and influential sets of guidelines for the medical care of transgender people was published in 2017 by the Endocrine Society (W. Hembree et al., “Endocrine Treatment of Gender-Dysphoric/Gender-Incongruent Persons: An Endocrine Society Clinical Practice Guideline,” Journal of Endocrinology & Metabolism 102(11), November 2017, p. 3869-3903). This document explicitly sought to adopt an “evidence-based” approach:

The task force followed the approach recommended by the Grading of Recommendations, Assessment, Development, and Evaluation group, an international group with expertise in the development and implementation of evidence-based guidelines.

The Endocrine Society issued specific guidelines in five separate areas:

  1. Evaluation of youth and adults (5 guidelines)
  2. Treatment of adolescents (6 guidelines)
  3. Hormonal therapy for transgender adults (4 guidelines)
  4. Adverse outcome prevention and long-term care (7 guidelines)
  5. Surgery for sex reassignment and gender confirmation (6 guidelines)

Evaluating the Quality of the Evidence

The key question is—what is the quality of the evidence in support of the guidelines? I decided to examine that issue.

There are three types of guidelines:

  • An “Ungraded Good Practice Statement”—essentially supported by no evidence (beginning “We advise . . .”)
  • A “weak recommendation” (beginning “We suggest . . .”)
  • A “strong recommendation” (labeled “We recommend . . .”)

Only with the strong recommendations does the task force express “confidence that persons who receive care according to [them] . . . will derive, on average, more benefit than harm.”

Then for each of the “recommendations” (weak or strong) they give a rating of the “quality of the evidence” in support of that recommendation, on a four-point scale: very low, low, moderate, or high.

How Strong is the Evidence Regarding Gender Transition Procedures for Minors?

If we omit category 3 (which applies only to adults), there are 24 guidelines that are generally relevant to the procedures at issue in Vulnerable Child Protection Acts—puberty blockers, hormones for adolescents, and surgery.

Of these 24 guidelines:

  • 5 are ungraded good practice statements (no evidence);
  • 2 are weak recommendations with very low evidence; and
  • 9 are weak recommendations with low evidence.

That means only 8 of the 24 “guidelines” are even “strong” recommendations—one third of the total. Of those:

  • 2 are supported by very low evidence;
  • 5 are supported by low evidence; 
  • Only 1 is supported by even “moderate” evidence;
  • None are supported by “high quality” evidence.

Evaluating the Recommendations

Several of the “strong recommendations” and other guidelines relate to controlling the potential negative side effects of gender transition, rather than actually recommending the transition procedure.

For example, the lone guideline supported by even “moderate” evidence was one warning patients to look into “fertility preservation” (some method of storing sperm or eggs), because the procedures may permanently sterilize the individual:

1.5. We recommend that clinicians inform and counsel all individuals seeking gender-affirming medical treatment regarding options for fertility preservation prior to initiating puberty suppression in adolescents and prior to treating with hormonal therapy of the affirmed gender in both adolescents and adults.

Some of the guidelines actually support what Vulnerable Child Protection Acts would do. Very few procedures which actually follow the Endocrine Society guidelines would also violate South Dakota’s VCPA, HB 1057.

For example, they recommend strongly (with low evidence) initiating cross-sex hormone treatment only after confirming “sufficient mental capacity to give informed consent, which most adolescents have by age 16 years” (2.4). (Guideline 2.5 says there may be exceptions to this, but it is supported by “very low” evidence.)

In addition, a “weak recommendation” with low evidence (5.5) suggests “that clinicians delay gender-affirming genital surgery . . . until the patient is at least 18 years old.”

Another weak recommendation (supported by very low evidence) suggests the timing of breast surgery be determined case by case, because “There is insufficient evidence to recommend a specific age requirement.” However, the lack of evidence would suggest that such radical, body-altering surgery should be postponed to a later age if possible, not accelerated.

Meanwhile, the key guidelines in support of puberty suppression (2.1 and 2.2) are only weak recommendations, supported by low evidence. The strong recommendation that some patients (over age 18) be referred for genital surgery is supported by “very low” evidence.

A Weak Evidence Base

In summary, the claim that these treatments are “evidence-based” is misleading, because the quality of the evidence in this field (even for the Endocrine Society’s “strong” recommendations) is low.

Until the quality of the evidence becomes higher, gender transition procedures must be considered experimental procedures at best.