1. University of Calabar Teaching Hospital; Po Box 3124 Calabar Cross River State Nigeria 540001
2. Stellenbosch University; Centre for Evidence-based Health Care, Faculty of Medicine and Health Sciences; Francie van Zijl Drive Tygerberg Cape Town South Africa 7505
3. South African Medical Research Council; South African Cochrane Centre; PO Box 19070 Tygerberg Western Cape South Africa 7505
4. University of California, San Francisco; Global Health Sciences; San Francisco California USA 94105