[1] Univ Western Australia, Sch Populat Hlth, Perth, WA 6009, Australia
[2] Royal Australian Coll Gen Practitioners, Western Australian Fac, Perth, WA, Australia
[3] Fremantle Hosp & Hlth Serv, Dept Resp Med, Perth, WA, Australia
[4] Fremantle Hosp & Hlth Serv, Cardiac Care Unit, Perth, WA, Australia
[5] Sir Charles Gairdner Hosp, Dept Resp Med, Perth, WA, Australia
[6] Sir Charles Gairdner Hosp, Dept Cardiovasc Med, Perth, WA, Australia
[7] Gen Practice Div Western Australia Ltd, Perth, WA, Australia