This is the document I referred to above - it was produced as part of the consultation for the specification policy for gender identity services.
www.engage.england.nhs.uk/consultation/specialised-services-consultation/user_uploads/gendr-ident-policy.pdf
I think it would be hard to argue that this was not the product of experts. I have picked out a few phrases here - despite the poor evidence, somehow gender reassignment is "deemed" to have good outcomes - but I really can't find a lot of evidence to back this up here.
From section 5, evidence base:
"The evidence base for treatment of gender dysphoria is largely comprised of low- graded (with respect to “level of evidence” scoring systems) papers"
"Studies appear to suggest a positive impact of treatment on gender dysphoria, psychological status, sexual functioning and quality of life. Mortality from suicides seems to be high despite treatment. However, the quality of evidence which these findings are based is low, and in some instances there are conflicting results."
"Overall, there is only limited evidence to demonstrate the efficacy of hormonal therapy or gender reassignment surgery with regard to long-term complications or physical functional status. "
"Quality of life scores for transsexual patients were the same or better than those of control patients for some subscales (emotions, sleep, incontinence, symptom severity, and role limitation), but worse in other domains (general health, physical limitation, and personal limitation). "
"It is difficult to determine the effectiveness of hormones alone in the relief of gender dysphoria"
"There is, to date, only limited outcome evidence for the treatment of gender dysphoria. In addition, such evidence of efficacy and treatment satisfaction that is available is generally of a low level"
"With respect to drug therapy, there are substantial variations in current UK prescribing practice and inadequate evidence or even consensus to agree what constitutes “best practice"
"One troubling report (Newfield et al., 2006) documented lower scores on quality of life (measured with the SF-36) for FtM patients than for the general population"
Yes, if a person is utterly miserable and suicidal, all these risks will be as nothing. However, that does not make good basis for celebrating and applauding a teenager's coming out as trangender as we are being asked to do. It must be the first priority to help and support that child to come to terms with their own body, (the one they were born in) and to be as gender non-conforming as they want. If that includes changing pronouns and name - personally I don't care if it works - but avoiding unknown harms from avoidable medical intervention - yes please!