[1] Curtin Univ, Curtin Med Sch, Perth, WA, Australia
[2] Sir Charles Gairdner Hosp, Dept Resp Med, Perth, WA, Australia
[3] Inst Resp Hlth, Perth, WA, Australia
[4] ChestRad Radiol, Perth, WA, Australia
[5] Univ Western Australia, Sch Populat & Global Hlth, Perth, WA, Australia