Corretto lo storico studio svedese: la rianalisi non trova benefici per la salute mentale dalla chirurgia di genere

Correzione di uno studio chiave: Nessuna prova che gli interventi chirurgici "di affermazione di genere" migliorino la salute mentale

Commentario e analisi Chirurgia Salute mentale e suicidio

Authors: Society for Evidence-Based Gender Medicine (SEGM)
Journal: Society for Evidence-Based Gender Medicine (SEGM)
Year: 2020
Source: segm.org/ajp_correction_2020

Summary

A 2019 Swedish study by Bränström and Pachankis in the American Journal of Psychiatry was widely reported as showing that gender surgery improves mental health. People whose surgery was longer ago were less likely to be getting mental health care in 2015; hormones showed no such link. After critical letters, the journal asked statisticians to review it and asked the authors to compare 1,018 surgery patients with 1,018 similar people who had not had surgery. That comparison showed 'no advantage of surgery'. The 2020 correction called the pro-surgery conclusion 'too strong' and fixed a 48% vs 37.9% error. This SEGM (Society for Evidence-Based Gender Medicine) article explains the correction accurately. But the new comparison was an afterthought, not part of the original plan, the paper was not withdrawn, and SEGM is a side in the debate.

Key findings

Lo studio originale del 2019 utilizzava i registri sanitari nazionali svedesi relativi a 9,7 milioni di persone, tra cui 2.679 con diagnosi di incongruenza di genere tra il 2005 e il 2015, ed esaminava le cure per la salute mentale in un solo anno, il 2015.
Non aveva trovato alcun legame tra gli anni di assunzione di ormoni e le cure per la salute mentale, ma una probabilità inferiore di circa l'8% di ricevere cure per ogni anno trascorso dall'ultimo intervento. Gli autori dicevano che questo sosteneva l'offerta della chirurgia.
Dopo lettere critiche di ricercatori di Svezia, Norvegia, Stati Uniti e Regno Unito, il direttore della rivista ha disposto due revisioni statistiche e ha chiesto agli autori di confrontare 1.018 pazienti operati con 1.018 pazienti simili non operati.
La correzione di agosto 2020 affermava che questo confronto mostrava «nessun vantaggio della chirurgia» per visite per disturbi dell'umore o d'ansia, prescrizioni o ricoveri dopo tentativi di suicidio.
La correzione definiva «troppo forte» la conclusione favorevole alla chirurgia perché lo studio non seguiva le persone nel tempo né assegnava i trattamenti in modo casuale. Ha inoltre corretto la quota di chi aveva fatto l'intervento dal 48% al 37,9%.
L'articolo non è stato ritirato. È stato ripubblicato con una nota aggiuntiva e, nella loro risposta, gli autori hanno difeso il risultato sul tempo trascorso dall'intervento e sostenuto che i pazienti non operati sono un cattivo gruppo di confronto.
Nel nuovo confronto, i pazienti operati avevano un po' più probabilità di essere curati per ansia e avevano 13 contro 7 ricoveri dopo tentativi di suicidio. Questa differenza poteva facilmente essere dovuta al caso, e SEGM afferma che non dimostra un danno.
La maggior parte degli interventi era recente: oltre il 75% dei 1.018 era entro tre anni dal 2015 e solo 19 risalivano a 10 anni o più prima, quindi lo studio dice poco sui risultati a lungo termine.

Abstract

In October 2019, the American Journal of Psychiatry (AJP) published a study from the Karolinska Institute in Sweden, and the Yale School of Public Health which reported that “gender-affirming" surgeries for gender dysphoric patients are associated with improved mental health outcomes. Looking at mental health utilization in the year 2015, a retrospective analysis showed that the more time passed since surgery, the fewer mental services were utilized by patients, with an average 8% reduction in mental health utilization for each year following surgery. From this, the study concluded that surgery has a beneficial effect on mental health, and that benefits continue to accrue over time. However, following a reanalysis of the data, this conclusion has now been officially corrected to indicate that there is “no advantage of surgery.”

Conclusion

After reanalysis with a control group comparing gender dysphoric patients who received surgery to those who did not, no statistically significant difference was found in mental health utilization measures. The AJP correction stated the original conclusion that 'the longitudinal association between gender-affirming surgery and lower use of mental health treatment lends support to the decision to provide gender-affirming surgeries' was too strong. The Society for Evidence-Based Gender Medicine (SEGM) concluded that no mental health benefit of gender-affirming surgery was demonstrated in the corrected analysis.

Methodological limitations

Written by a group with a position: This record is SEGM's explanation, not the correction itself. SEGM argues for caution in gender medicine and notes that some of its advisers wrote the critical letters, so its framing should be read with that in mind.
New comparison was an afterthought: The surgery vs no-surgery comparison was not part of the original question. The correction notes that the groups may differ in several other ways, so the 'no difference' result is also not strong proof either way.
Comparison group mixes different people: The authors argued that people diagnosed with gender incongruence who had not had surgery include many who never wanted it. So finding no difference does not show surgery has no benefit for those who seek it, a point SEGM accepts.
Corrected, not withdrawn: The journal corrected the conclusion and reposted the article, but did not withdraw the time-since-surgery link, which the authors stood by. Saying 'the study was wrong' goes further than the formal correction.
One-year snapshot: Both analyses looked at mental health treatment in 2015 only, comparing different people at different times since surgery rather than following the same people over time. They cannot show change in any one person.
Indirect measures: Visits, prescriptions and hospital stays measure use of services, not symptoms or quality of life. Required mental health assessments before surgery may have pushed up service use around the time of surgery.
Deaths and moves abroad missed: Only people alive and living in Sweden in 2015 were included. If people died, including by suicide, after surgery, those with surgery long ago would look healthier than they were. The authors admitted this.
Patients changed over time: More recent patients were younger, more often born female and more often had other mental health problems. This alone could explain why people with older surgeries used fewer services, regardless of surgery.
Many tests, one hit: The single positive result in the original was only just clear of chance, and came alongside several other measures tested without allowing for the extra chance of a fluke, as letter writers pointed out.
Doubtful 'lost patients' claim: SEGM suggests about 90% of patients were 'lost', because only 19 had surgery before 2005 compared with 324 in an earlier Swedish study. But the study only included people diagnosed from 2005 to 2015, so people treated earlier were mostly outside the study rather than lost.
Too few suicide-related cases: Hospital stays after suicide attempts (13 vs 7) are too few to support conclusions either way, and the new comparison was too small to test this properly.

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Summary

Key findings

Abstract

Conclusion