For anyone interested in the study referred to in the Finnish review, a search suggests that it is this one (the relevant details match up):
Costa R, Dunsford M, Skagerberg E, Holt V, Carmichael P, Colizzi M. Psychological support, puberty suppression, and psychosocial functioning in adolescents with gender dysphoria. J Sex Med 2015;12:2206–2214
To answer some of suggestionsplease1's questions, as the full text is behind a paywall:
And it's Finnish not UK based evidence. I'm not allowed to include any non-UK evidence because it's not relevant to our particular culture and population, but you apparently are?
It's a UK study conducted in London at GIDS.
But this study would obviously fall far short of your requirements for us to consider - where is the reference to the matched cohort design? What a poorly designed study eh, not to include that.
This was a longitudinal study of 2 cohorts of gender-dysphoric young people. All 201 participants received psychological assessment and intervention for 6 months via GIDS before eligibility for puberty blockers was assessed. At the 6-month point, participants who were assessed as eligible for puberty blockers were assigned to one of 2 cohorts.The immediate-eligibility cohort received psychological support plus pharmacological puberty suppression, while the delayed-eligibility cohort received psychological support only. Assignment to the delayed-eligibility cohort was on the following basis: "In those specific cases clinicians needed more time to make the decision of starting GnRHa because of possible comorbid psychiatric problems and/or psychological difficulties."
Both cohorts were followed up 12 months and 18 months. Results for both cohorts were compared to a large sample (N=169) of young individuals without observed psychological/psychiatric symptoms who completed the same adolescent psychosocial function measures as the two gender-dysphoric groups.
Of course you will know full well that the baseline characteristics for both cohorts are likely very different - namely in the degree to which they experienced gender dysphoria in the first place - those experiencing greater distress (amongst other considerations), would have been more likely to be put forward for GnRH analogues in addition to psychological intervention, and those for whom it was considered that their distress could be adequately managed by psychological intervention alone of course were in that cohort.
No, the opposite was true. The cohort assigned to the immediate-eligibility group had numerically (though not statistically) higher measures of psychosocial function than the delayed-eligibility group, and the delayed group were assigned to that cohort precisely because they demonstrated signs of more significant psychiatric or psychological difficulties.
You will, of course, know that. It would be unethical to proceed in any other way - unless you think they're just taking the 270 kids and randomly assigning them to a treatment group with no individualised plan?
It is not unethical to compare two treatment pathways where definitive objective evidence of clinical benefit is lacking, precisely in order to collect that missing evidence.
But of course, as it happens the results you have found show that all cohorts fared well.
The results are more nuanced than that.
The study showed that measures of psychosocial function improved significantly across the entire participant group (pooled across both cohorts) after 6 months of psychological intervention and support. However, when each group was considered separately, significant improvement in psychosocial function was observed only in the delayed-eligibility cohort, who (according to the criteria for assignment to that cohort) showed signs of more serious psychological and psychiatric difficulties.
From the 6-month point, where the 2 cohorts diverged in the treatment received, the immediate-eligibility group (who received puberty blockers plus psychological support) showed significant improvement in psychosocial function at the 12- and 18-month follow-up points, compared to the 6-month point.
In contrast, the delayed-eligibility group (who received psychological support only) showed small numerical improvements in psychosocial function measures at 12 and 18 months, which were not statistically significant. However, in the delayed-eligibility group, psychosocial function at 12 and 18 months remained significantly better than at baseline (prior to starting any psychological intervention).
Also worth noting that, despite the apparent differences between outcomes for each cohort, direct comparison of psychosocial function at 18 months showed no statistically significant difference in psychosocial function between the group that had received puberty blockers plus psychological intervention and the group that had received psychological intervention only.
So this would obviously fall far, far short of the rigorous study design that you need to consider, so I don't know why you're even referring to it? It doesn't count right? Just like the the scores of studies I have linked to.
The study is flawed, but not for the reasons you suggest.
This study had enormous problems with participant retention. By the 12-month time point, less than 2/3 of participants remained in each cohort, and by the 18-month point, only around 1/3 of participants in each cohort remained in the study. The reasons for loss to follow-up are not reported, so we have no idea whether these participants left because their mental health improved or because it worsened. That is a huge drop-out rate - so big that it raises questions about how well-matched the final cohorts remaining after 18 months were, and makes it very difficult to draw meaningful conclusions about the impact of puberty blockers.
The summary version - psychological intervention improves mental health in gender dysphoric adolescents, especially those who are experiencing greater psychological difficulties or psychiatric comorbidities. Any additive benefit of puberty blockers is difficult to evaluate due to the very high dropout rate during follow-up.