Funding for this research was provided by:
University of Warwick
Received: 6 August 2018
Revised: 28 February 2019
Accepted: 22 March 2019
First Online: 20 May 2019
Compliance with ethical standards
: The authors declare that there is no conflict of interest.
: The views expressed in this publication are those of the authors and not necessarily those of the NHS, the National Institute for Health Research, or the Department of Health.