Complete national register follow-up eliminates loss-to-follow-up bias.

A nationwide Finnish study followed all individuals referred to gender identity services between 1996 and 2019 using mandatory national health registers, ensuring virtually complete follow-up with no attrition. By linking multiple administrative datasets over up to 25 years, it avoided common limitations of earlier research, including small samples, selective drop-out, and reliance on self-report. The study provides a comprehensive population-level assessment of long-term psychiatric treatment needs in this cohort.

Ruuska, S.-M., Tuisku, K., Holttinen, T., and Kaltiala, R. (2026). “Psychiatric Morbidity Among Adolescents and Young Adults Who Contacted Specialised Gender Identity Services in Finland in 1996–2019: A Register Study,” Acta Paediatrica: 1–9. https://doi.org/10.1111/apa.70533.