1. The University of Edinburgh; Asthma UK Centre for Applied Research, Usher Institute of Population Health Sciences and Informatics; Teviot Place Edinburgh UK EH8 9AG
2. The University of Edinburgh; Division of Community Health Sciences: GP section; 20 West Richmond Street Edinburgh UK EH8 9DX
3. The University of Western Australia at Fremantle Hospital; Department of Emergency Medicine; Alma Street Fremantle Western Australia Australia 6160
4. Faculty of Medicine, University of Manitoba; Department of Pediatrics & Child Health; Department of Immunology; Winnipeg MB Canada