1. South African Medical Research Council; Cochrane South Africa; Francie van Zijl Drive, Parow Valley Cape Town Western Cape South Africa 7505
2. Stellenbosch University; Centre for Evidence-based Health Care, Faculty of Medicine and Health Sciences; Cape Town South Africa
3. Groote Schuur Hospital; Division of Cardiology; Observatory 7925 Cape Town South Africa
4. McMaster University; Department of Clinical Epidemiology and Biostatistics; 50 Charlton Ave E Room H325, St. Joseph's Healthcare Hamilton ON Canada L8N 4A6
5. University of Cape Town; Department of Statistical Sciences; Cape Town South Africa
6. University of Cape Town; Department of Medicine; Cape Town South Africa