Close James, Valderas Jose M, Byng Richard, Britten Nicky, Lloyd Helen
Community and Primary Care Research Group, Plymouth University Peninsula Schools of Medicine and Dentistry, Plymouth Science Park, Derriford, Plymouth PL6 8BX, UK.
University of Exeter Medical School, RSJ02, Smeall Building, St Luke's Campus, Exeter EX1 2LU, UK.
BMJ. 2017 Dec 4;359:j5541. doi: 10.1136/bmj.j5541.