1 School of Public Health and Family Medicine, University of Cape Town, Observatory 7925, South Africa; Burden of Disease Research Unit, Medical Research Council, Johannesburg, South Africa. Electronic address: richard.matzopoulos@uct.ac.za.
2 School of Public Health and Family Medicine, University of Cape Town, Observatory 7925, South Africa.
3 Department of Psychology, School of Human and Community Development, University of the Witwatersrand, Johannesburg, South Africa.