[1] South African Med Res Council, Cochrane South Africa, Francie van Zijl Dr, ZA-7501 Cape Town, South Africa
[2] Stellenbosch Univ, Dept Nursing & Midwifery, Francie van Zijl Dr, ZA-7505 Cape Town, South Africa
[3] Univ Washington, Dept Epidemiol, Seattle, WA 98195 USA
[4] Univ Cape Town, Div Epidemiol & Biostat, Anzio Rd, ZA-7925 Cape Town, South Africa
[5] African Inst Dev Policy, POB 14688-00800, Nairobi, Kenya
[6] Univ Buea, Fac Hlth Sci, POB 63, Buea, Cameroon
[7] Stellenbosch Univ, Dept Global Hlth, Div Epidemiol & Biostat, Francie van Zijl Dr, ZA-7505 Cape Town, South Africa