[1] Sir Charles Gairdner Hosp, Dept Pulm Physiol & Sleep Med, West Australian Sleep Disorders Inst, Nedlands, WA 6009, Australia
[2] Univ Sao Paulo, Univ Med Sch, Sao Paulo, Brazil
[3] Monash Univ, Epidemiol & Prevent Med, Melbourne, Vic 3004, Australia
[4] Childrens Hosp Westmead, Resp Med, Sydney, NSW, Australia
[5] Univ British Columbia, Resp Med, Vancouver, BC V5Z 1M9, Canada
[6] Univ Calgary, Pathol, Calgary, AB, Canada