[1] Menzies Sch Hlth Res, Darwin, NT, Australia
[2] Charles Darwin Univ, Inst Adv Studies, Darwin, NT, Australia
[3] Australian Natl Univ, Natl Ctr Epidemiol & Populat Hlth, Coll Med & Hlth Sci, Canberra, ACT, Australia
[4] Univ New S Wales, Sch Publ Hlth & Community Med, Sydney, NSW, Australia