Funding: This report is independent research arising from a National Institute of Health Research (NIHR) Doctoral Research Fellowship awarded to Haroon Ahmed, and supported by Health and Care Research Wales (HCRW) (Grant number: DRF-2014-07-010). The views expressed in this publication are those of the authors and not necessarily those of the NIHR, NHS Wales, HCRW or the Welsh Government. Hywel Jones is supported by The Farr Institute @ CIPHER, a Medical Research Council led multi-funder initiative for e-health research, MRC Grant Number: MR/K006525/1. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of this manuscript.Peer reviewedPublisher PD