Funding Acknowledgement: This study is funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment (HTA) programme (project number 12/140/01).

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.

Sponsorship: This study is sponsored by North Bristol NHS Trust (NBT).

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

REDCap Acknowledgement: Study data are collected and managed using REDCap (Research Electronic Data Capture, Harris PA, et al. J Biomed Inform. 2009 Apr;42(2)377-81) hosted at the University of Bristol.

ISRCTN registry: ISRCTN56164274

ClinicalTrials.gov Identifier: NCT02193451