1 Department of Medicine, University of Calgary, Calgary, AB, Canada; Department of Community Health Sciences, University of Calgary, Calgary, AB, Canada. Electronic address: kerri.johannson@ahs.ca.
2 Department of Biostatistics and Epidemiology, University of California San Francisco, San Francisco, CA.
3 Département de Médecine, Centre Hospitalier de l'Université de Montréal, Montréal, QC, Canada.
4 Department of Medicine, University of California San Francisco, San Francisco, CA.
5 Division of Environmental Health Sciences, School of Public Health, University of California, Berkeley, CA.
6 Department of Medicine, University of California San Francisco, San Francisco, CA; Division of Environmental Health Sciences, School of Public Health, University of California, Berkeley, CA.