1. Health Systems Research Unit, Medical Research Council, Cape Town, South Africa; and Nelson R Mandela School of Medicine, University of KwaZulu-Natal, Durban, South Africa
2. KwaZulu-Natal Research Institute for Tuberculosis and HIV (K-RITH), Durban, South Africa
3. Nelson R Mandela School of Medicine, University of KwaZulu-Natal, Durban, South Africa
4. KwaZulu-Natal Department of Health, Pietermaritzburg, South Africa
5. Biostatics Unit, Medical Research Council, Durban, South Africa
6. Department of Medicine, Montefiore Medical Center and Albert Einstein College of Medicine, Bronx, New York, USA
7. University of Michigan School of Medicine, Ann Arbor, Michigan, USA; Harvard University School of Medicine, Boston, Massachusetts, USA
8. Centre for the AIDS Programme of Research in South Africa (CAPRISA), University of KwaZulu-Natal, Durban, South Africa