1Ottawa Methods Centre, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
2Department of Epidemiology and Community Medicine, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
3Università di Modena e Reggio Emilia, Modena, Italy
4Centro Cochrane Italiano, Istituto Ricerche Farmacologiche Mario Negri, Milan, Italy
5Centre for Statistics in Medicine, University of Oxford, Oxford, United Kingdom