Authors: Sudha Sundar; Caroline Rick; Francis Dowling; Pui Au; Kym Snell; Nirmala Rai; Rita Champaneria; Hilary Stobart; Richard Neal; Clare Davenport; Susan Mallett; Andrew Sutton; Sean Kehoe; Dirk Timmerman; Tom Bourne; Ben Van Calster; Aleksandra Gentry-Maharaj; Usha Menon; Jon Deeks Journal: BMJ Open Date: 2016-08-09 Impact factor: 2.692