Studies › Follow-up · Last reviewed 2026-05-16
Follow-up studies overview
Summary
Long-term data on the Dutch Protocol remain limited. This page collects published cohort and outcome studies, with sample size, follow-up duration, attrition and main findings. Systematic reviews by NICE (2020), SBU (2022) and the University of York for the Cass Review (2024) classify the cumulative evidence as low to very low.
Overview (selection)
| Study | n | Follow-up | Main finding |
|---|---|---|---|
| de Vries 2011 | 70 | ≥ 2 yrs GnRHa | Improvement in psychological functioning |
| de Vries 2014 | 55 | 1 yr post-op | Dysphoria resolved, functioning at peer level |
| Costa et al. 2015 | 201 (UK, GIDS) | 18 months | No improvement vs. control group |
| Carmichael 2021 | 44 (UK, GIDS early intervention) | ~3 yrs | No significant improvement on mental outcome measures |
| Brik et al. 2020 | 269 | ~2.4 yrs | GnRHa-phase discontinuation 1.9% |
| van der Loos 2022 | 720 | 3–14 yrs | 98% start CSH after GnRHa; continuation bias reported |
| van der Loos 2023 | 1,766 | NPB/CSH continuation | 1.9% stop before CSH; 0.5% reported regret |
Common limitations
- No RCTs in this clinical domain.
- Varying attrition rates (0–22%).
- Heterogeneous outcome measures — comparison between studies hindered.
- Long-term data (10+ years) largely missing.
Conclusion of systematic reviews
Both SBU (2022) and the University of York systematic reviews for the Cass Review (2024) classify the level of evidence as "very low" per GRADE criteria — primarily due to absence of control groups, limited follow-up and risks of selection and attrition bias.1
Critical note
The claim "98% start CSH after GnRHa" is presented by proponents as confirmation of diagnostic certainty; by critics as evidence that the "diagnostic phase" is not a reflection phase but a first treatment step. Both interpretations are compatible with the same data — which demonstrates that the outcome measures themselves are not informative enough to answer the crucial question (does this treatment help, compared with no treatment?). A Finnish register study (Ruuska et al. 2026, cited in public commentary) reports increasing psychiatric care consumption after treatment.2
See also
- Individual study summaries: de Vries 2011, de Vries 2014, Costa/Carmichael (replication)
- Attrition analysis: Sample size and attrition
- Methodological criticism: Methodological criticism, Biggs
- Systematic evaluation: Cass Review, SBU
- Clinical aftercare structure: Follow-up in the Dutch Protocol
- People register — de Vries, van der Loos, Costa, Carmichael.
- Timeline — follow-up publications in chronology.
- Original publications — full bibliography.
- FAQ · Glossary.
Footnotes
- Taylor J, Mitchell A, Hall R, et al. Interventions to suppress puberty in adolescents experiencing gender dysphoria. Arch Dis Child. 2024; University of York / Cass Review systematic review.
- Genderzorgen. Transgender care under scrutiny. Substack, 10 April 2026 (translation by editors).