[1] Univ Witwatersrand, Wits Dev Pathways Hlth Res Unit, SAMRC, Johannesburg, South Africa
[2] Univ Bristol, Ctr Acad Mental Hlth Addict & Suicide Res, Sch Social & Community Med, Bristol, England
[3] Univ Witwatersrand, DSI NRF Ctr Excellence Human Dev, Johannesburg, South Africa
[4] Univ Bristol, Dept Social Med, MRC Integrat Epidemiol Unit, Bristol, England