Funding for this research was provided by:
National Institute for Health Research (HPRU-2012-10414.)
Health Education England (RTVLAIR)
Received: 24 January 2019
Accepted: 15 May 2019
First Online: 13 June 2019
Ethics approval and consent to participate
: Ethical approval was provided by the King’s College London ethics committee (RESCMR-15/16-1561).
: Not applicable
: The authors declare that they have no competing interests.