Funding Acknowledgement: This project is funded by the National Institute for Health (NIHR) (project reference CS-2016-16-09).

Department of Health Disclaimer: The views and opinions expressed are those of the author(s) and not necessarily those of the NIHR or the Department of Health and Social Care.

Bristol Trials Centre acknowledgement: This study was designed and delivered in collaboration with the Bristol Trials Centre (BTC), a UKCRC registered clinical trials unit (CTU) and, is in receipt of National Institute for Health Research CTU support funding.

Sponsor acknowledgement: This study is sponsored by North Bristol NHS Trust (United Kingdom [UK]).