Studies › 2014 · Last reviewed 2026-05-16
de Vries et al. (2014) — the Amsterdam study
Young adult psychological outcome after puberty suppression and gender reassignment. Pediatrics. 2014;134(4):696–704. Author: Annelou de Vries. Position in chronology: timeline 2014.
Summary
Prospective follow-up of 55 young adults who completed the full Dutch Protocol — GnRHa, cross-sex hormones and gender-affirming surgery. One year post-operatively (mean age 20.7) gender dysphoria had resolved, wellbeing was comparable to peers and no participant reported regret. The study is the central empirical citation behind the international adoption of the protocol.
1. Design
| Type | Prospective cohort study |
|---|---|
| Sample T0 | n = 70 |
| Sample T2 | n = 55 (29 MtF / 26 FtM) |
| Attrition | 15 (including 1 death from post-operative complication) |
| Measurement points | T0 (pre-GnRHa), T1 (start of hormones), T2 (≥ 1 yr post-operative) |
2. Main outcomes
- Gender dysphoria (UGDS) resolved at T2.
- Body image (Body Image Scale): significant improvement.
- Psychological functioning comparable to peers in the general population.
- 0% reported regret or detransition.
- One participant died from post-operative necrotising fasciitis after vaginoplasty.
3. Limitations stated by the authors
- No control group.
- Limited generalisability (single-centre, selected cohort).
- Possible under-representation of poorer-functioning patients among the attrited.
- Follow-up limited to 1 year post-operatively.
4. Later criticism
The study has been criticised methodologically on multiple points, notably by Michael Biggs (Oxford, 2022) and Susan Bewley et al. (BMJ, 2019). See /studies/methodological-criticism/. The Cass Review (2024) classifies the level of evidence derivable from this study as "low to very low certainty".1
See also
- People register — Annelou de Vries, Michael Biggs.
- Timeline 2014 — publication in chronological context.
- Previous publication: de Vries 2011 — first follow-up.
- Detailed attrition analysis (15 of 70): Sample size and attrition.
- Methodological re-evaluation: Biggs 2023, Methodological criticism.
- Replication problems: Replication attempts, Tavistock GIDS (UK).
- Systematic evaluation: Cass Review 2024, SBU 2022.
- Broader context: Follow-up studies overview.
- FAQ · Glossary.
Footnotes
- Cass H. Independent review of gender identity services for children and young people: final report. NHS England; April 2024. Appendix 8 (systematic review University of York).