1. Department of Epidemiology, Biostatistics, and Occupational Health, McGill University, Montreal, QC H3A 1A2, Canada;
2. Sansom Institute for Health Research, Division of Health Sciences, University of South Australia, Adelaide SA 5001; School of Population Health and Clinical Practice, University of Adelaide, SA 5005 Australia;
3. School of Community and Social Medicine, University of Bristol, Bristol BS8 2BN, United Kingdom;
4. MRC Center for Causal Analyses in Translational Epidemiology, University of Bristol, Bristol BS8 2BN, United Kingdom;