[1] Univ Warwick, Warwick Med Sch, Div Hlth Sci, Coventry CV4 7AL, England
[2] Univ Warwick, Warwick Med Sch, Warwick Ctr Global Hlth, Div Hlth Sci, Coventry CV4 7AL, England
[3] Stellenbosch Univ, Dept Global Hlth, Div Epidemiol & Biostat, Stellenbosch, South Africa
[4] Karolinska Inst, Dept Publ Hlth IHCAR, Stockholm, Sweden