1 Centre for Evidence-based Health Care, Stellenbosch University, Stellenbosch, South Africa and Cochrane South Africa, South African Medical Research Council, Cape Town, South Africa. E-mail: charlesw@sun.ac.za.
2 Centre for Evidence-based Health Care, Stellenbosch University, Stellenbosch, South Africa and.
3 Liverpool School of Tropical Medicine, Liverpool, UK and Malawi-Liverpool-Wellcome Trust Clinical Research Programme, College of Medicine, Blantyre, Malawi.