Evidence: handle with care

The headline reads "What are puberty blockers? What are the benefits and risks for transgender children?"

The article presents as an explainer, with a factual and professional tone. 

It's on the website of the Murdoch Children's Research Institute (MCRI), the research partner of Australia's most influential gender clinic at the Royal Children's Hospital (RCH) Melbourne. The article was first published by The Conversation, with its motto “Academic rigour, journalistic flair”.

The authors are Dr Ken Pang, affiliated with both MCRI and the RCH gender clinic, and three people with University of Sydney appointments. I will refer to them as "The Conversation authors".

Their article cites a systematic review of the scientific literature, which is encouraging because such reviews represent high-quality evidence, more reliable than the potential groupthink of "gender-affirming" experts.

Of the 50 papers in this systematic review of the evidence for puberty blockers, The Conversation authors cherry-picked one, and they say: "The study the [systematic] review authors identified as being the highest quality found significantly improved psychological outcomes". 

"Puberty blockers reduced suicidal thoughts and actions in transgender adolescents compared to those who had not accessed the treatment."

The study they focus on is a 2020 publication by Dutch psychiatrist Dr Anna van der Miesen and colleagues from the famous Amsterdam gender clinic.

The Conversation authors overstate the explanatory power of this study of van der Miesen et al, by omitting a crucial limitation acknowledged by the Dutch study researchers.

The Dutch paper says: “[T]he cross-sectional design of this study with different participants in the groups before and after puberty suppression may potentially limit the results with participants being different on characteristics not measured and controlled for."

“The present study can, therefore, not provide evidence about the direct benefits of puberty suppression over time and long-term mental health outcomes.

“Conclusions about long-term benefits of puberty suppression should thus be made with extreme caution, needing prospective long-term follow-up studies with a repeated-measure design with individuals being followed over time to confirm the current findings.”

Nor do The Conversation authors make clear the overall conclusions of the systematic review they cite, conclusions at odds with the suggestion of clear evidence that puberty blockers confer psychological benefits.

Of the 50 papers in the review, van der Miesen's was the only study rated as high quality; 24 low-quality studies were excluded from the synthesis and the other 25 studies were moderate quality.

The systematic review concluded:

• "No high-quality studies were identified that used an appropriate study design to assess the outcomes of puberty suppression in adolescents experiencing gender dysphoria/incongruence. (Remember, Dr van der Miesen and her colleagues had conceded the weak explanatory power of their cross-sectional design.)

• "There is insufficient and/or inconsistent evidence about the effects of puberty suppression on gender-related outcomes, mental and psychosocial health, cognitive development, cardiometabolic risk, and fertility. 

• "There is consistent moderate-quality evidence, although from mainly pre-post studies, that bone density and height may be compromised during treatment.

The Conversation authors were also reticent about the origins of the systematic review they relied on to promote puberty blockers. They refer to it simply as "a 2024 systematic review". 

Click on the link and it turns out to be one of the systematic reviews undertaken by the UK University of York on the orders of Dr Hilary Cass during her four-year inquiry into youth gender dysphoria. York is a centre of expertise for systematic reviews.

Dr Cass has complained about "misinformation" directed at her 2024 report and systematic reviews.

That same year, in the context of politically charged litigation before the US Supreme Court, Dr Pang and other colleagues put their names to an amicus brief dismissing the York systematic reviews as "unreliable".

What word best sums up the approach to scientific evidence demonstrated by The Conversation article?

My full, updated article with links is here ⤵️⤵️⤵️