1. South African Medical Research Council, Cochrane South Africa, Cape Town, South Africa
2. Centre for Evidence-based Health Care, Division of Epidemiology and Biostatistics, Department of Global Health, Stellenbosch University, Cape Town, South Africa
3. Faculty of Medicine and Biomedical Sciences, University of Yaoundé I, Yaoundé, Cameroon
4. Division of Epidemiology and Biostatistics, School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa