Statistics from Altmetric.com
Contributors TT wrote the first draft of the this response letter. All coauthors reviewed and contributed to the final version.
Competing interests None.
Ethics approval Baseline: Ealing, Hounslow and Spelthorne and University College London research ethics committees. Follow-up@ St Mary's Hospital research ethics committee (ref. 07/H0712/109).
Provenance and peer review Not commissioned; internally peer reviewed.
Data sharing statement Data will be deposited with the UK Data Archive in 2014.
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.