http://www.biomedcentral.com/1471-2288/11/115 Do forward the link to your friends! (It's just a provisional pdf at this stage but the text won't change unless you list members find any typos that we missed!) Trisha Greenhalgh Professor of Primary Health Care and Director, Healthcare Innovation and Policy Unit Centre for Primary Care and Public Health Blizard Institute Barts and The London School of Medicine and Dentistry Yvonne Carter Building 58 Turner Street London E1 2AB t : 020 7882 7325 (PA) or 7326 (dir line) f : 020 7882 2552 e: <mailto:[log in to unmask]> [log in to unmask] http://www.icms.qmul.ac.uk/chs/staff/trishagreenhalgh.html