[1] Univ Melbourne, Allergy & Lung Hlth Unit, Ctr Epidemiol & Biostat, Sch Populat & Global Hlth, Melbourne, Vic, Australia
[2] La Trobe Univ, Dept Publ Hlth, Sch Publ Hlth & Human Biosci, Melbourne, Vic, Australia
[3] Monash Univ, Sch Publ Hlth & Prevent Med, Melbourne, Vic 3004, Australia
[4] Univ Bergen, Ctr Int Hlth, N-5020 Bergen, Norway