21:51 Nov 10 

correspondence about a clinical trial concerning patients with traumatic brain injury

21:47 Nov 10 

It does seem to be preferred in many publications in both UK and US, although variations are always possible.

21:44 Nov 10 

Please also see the additional UK sources I just added.
There may also be other terms to the standard "health care proxy" such as legal representative in some jurisdictions or regions. It might do no harm to use one and the other in parentheses as a synonym for such places.

21:36 Nov 10 

The term 'health care proxy' is only used in Scotland. 'Trustworthy person' isnt a term used in the UK, which leaves 'Carer': the problem there is that 'carers' have no legal standing.
This reference is guidance on consent for clinical trials for adults who cannot make decisions themselves:
www.nres.npsa.nhs.uk/EasySiteWeb/GatewayLink.aspx?alId=321

it uses the phrase 'legal representative'...
" Ethical review of CTIMPs
2.7 The main REC undertaking the review of a trial involving adults unable to consent for themselves is required to consider whether the research is justified having regard to the conditions and principles specified in Part 5 of Schedule 1 to the Clinical Trials Regulations. These include provisions for informed consent to be given by the subject’s legal representative. A definition of “legal representative” for this purpose is given in Part 1 of Schedule 1."

I'm assuming this trial document is for an incapacitated adult, because why else would they be sending information to a family member, rather than the patient????