1. eHealth Research Group, Centre for Population Health Sciences, University of Edinburgh Medical School, Edinburgh EH8 9AG, UK
2. School of Health in Social Science, University of Edinburgh, Edinburgh EH8 9AG, UK
3. School of Medicine, Pharmacy and Health, Wolfson Research Institute, Durham University, Stockton on Tees TS17 6BH, UK
4. Division of General Internal Medicine and Primary Care, Brigham and Women’s Hospital/Harvard Medical School, Boston 02120-1613, USA
5. School of Clinical and Experimental Medicine, College of Medical and Dental Sciences (CMDS), Medical School Building, University of Birmingham, Edgbaston B15 2TT, UK