[1] Univ Newcastle, Sch Nursing & Midwifery, Coll Hlth Med & Wellbeing, Callaghan, NSW, Australia
[2] Hunter Med Res Inst, Asthma & Breathing Programme, Lambton Hts, Australia
[3] Univ Newcastle, Sch Med & Publ Hlth, Coll Hlth Med & Wellbeing, Callaghan, NSW, Australia
[4] Univ Newcastle, Sch Med & Publ Hlth, Coll Hlth Med & Wellbeing, Callaghan, NSW, Australia
[5] John Hunter Hosp, Dept Resp & Sleep Med, Lambton Hts, Australia