The evidence base, plainly stated.

The adult literature on gender-affirming care is largely observational, cohort studies, registry studies, and patient surveys, rather than large randomised trials. Recent systematic reviews suggest:

• Improvements in gender dysphoria, depression, anxiety and quality of life for many adults receiving gender-affirming hormones or surgery.
• No substantive long-term harms identified in the literature reviewed, with the established risks (e.g. thromboembolism for oestradiol; haematocrit elevation for testosterone) being clinically manageable with monitoring.
• Detransition and regret rates are low in the longer-term adult literature (mostly under 1–2%), with social pressure and unsupportive environments cited more often than treatment regret itself; however, the data are imperfect.

Critically, the certainty of evidence is rated low to moderate across most outcomes. This is consistent with the wider critique that the adult evidence base is observational rather than experimental, but it doesn't follow that the treatments are ineffective. It means the size of the effect, and the population it best applies to, is not as precisely known as for some other areas of medicine.

The international landscape varies. WPATH's Standards of Care, Version 8 (2022) is the most widely-cited international clinical reference and recognises non-binary and individualised approaches. Several Nordic countries (Sweden, Finland) have moved to more cautious approaches for under-18s while preserving adult access. North American practice is variable. European practice spans both ends. None of these are perfect models; all are reasonable points of comparison.

For adults, gendr's scope, the broad direction across reputable systems is consistent: informed consent, individualised care, robust safeguarding, and ongoing access to long-term physical, mental and sexual health.