Authors: Simon G A Brown; Emma L Ball; Kyle Perrin; Catherine A Read; Stephen E Asha; Richard Beasley; Diana Egerton-Warburton; Peter G Jones; Gerben Keijzers; Frances B Kinnear; Ben C H Kwan; Y C Gary Lee; Julian A Smith; Quentin A Summers; Graham Simpson Journal: BMJ Open Date: 2016-09-13 Impact factor: 2.692