[1] Univ Witwatersrand, Dept Paediat & Child Hlth, Paediat Educ & Res Ladder, Johannesburg, South Africa
[2] Univ Witwatersrand, Chris Hani Baragwanath Acad Hosp, Div Pulmonol, Dept Paediat & Child Hlth, Johannesburg, South Africa
[3] Univ Pretoria, Dept Paeditr, Pretoria, South Africa
[4] Univ Cape Town, Dept Paediat & Child Hlth, Cape Town, South Africa
[5] Univ Cape Town, South African Med Res Council Unit Child & Adoles, Cape Town, South Africa
[6] Queensland Univ Technol, Queensland Childrens Hosp, Dept Resp & Sleep Med, Brisbane, Qld, Australia
[7] Queensland Univ Technol, Australian Ctr Hlth Serv Innovat, Brisbane, Qld, Australia
[8] Charles Darwin Univ, Menzies Sch Hlth Res, Child Hlth Div, Darwin, NT, Australia