Near the conclusion
The decision to rely on uncontrolled studies was exacerbated by other decisions. The Dutch clinicians chose incommensurable scales to measure gender dysphoria, which calls into question their finding that dysphoria declined following cross-sex hormones and surgery. Worse still, American clinicians eschewed the measures of psychological functioning used by the Amsterdam and London clinics (YSR, CBCL, and CGAS), thus ensuring that their tiny samples could not contribute to cumulative knowledge.
One final point to remember in evaluating published studies is that the field of transgender medicine is subject to the same publication bias as every other field: unsuccessful results will not be published. This bias is illustrated by the London clinic’s attempt to replicate the Amsterdam clinic’s findings: the lack of improvement on GnRHa appeared in print only after the clinic was taken to the High Court of Justice for England and Wales.