1 Clinical Trial Service Unit and Epidemiological Studies Unit (CTSU), Nuffield Department of Population Health, University of Oxford, Oxford, United Kingdom.
2 Department of Medicine, University of Toronto, Toronto, Ontario, Canada.
3 Division of Gastroenterology and Hepatology, University of Toronto, Toronto, Ontario, Canada; Scarborough Health Network Research Institute, Scarborough, Ontario, Canada; Division of Gastroenterology, Scarborough Health Network, Scarborough, Ontario, Canada.