1. Department of Epidemiology, University of California Los Angeles Fielding School of Public Health, Los Angeles, California, USA
2. Botswana-UPenn Partnership, Gaborone, Botswana, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
3. Botswana-UPenn Partnership, Gaborone, Botswana, Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
4. Department of Family Medicine and Public Health, Faculty of Medicine, University of Botswana, Gaborone, Botswana
5. Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada