Authors: Ethan K Gough; Erica E M Moodie; Andrew J Prendergast; Sarasa M A Johnson; Jean H Humphrey; Rebecca J Stoltzfus; A Sarah Walker; Indi Trehan; Diana M Gibb; Rie Goto; Soraia Tahan; Mauro Batista de Morais; Amee R Manges Journal: BMJ Date: 2014-04-15