1. University of North Carolina Project, Lilongwe, Malawi
2. Tidziwe Centre, Lilongwe, Malawi
3. Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, USA
4. Departments of Medicine and of Health Behavior, University of North Carolina at Chapel Hill, Chapel Hill, USA
5. Departments of Primary Care and Population Sciences and of Social Statistics and Demography, University of Southampton, Southampton, UK
6. Department of Health Behavior, School of Public Health, University of North Carolina at Chapel Hill, Chapel Hill, USA
7. Division of Epidemiology, The Ohio State University, Columbus, USA
8. Department of Health Behavior, University of North Carolina at Chapel Hill, Chapel Hill, USA