title: Differences in respiratory arousal threshold in Caucasian and Chinese patients with obstructive sleep apnoea.
abstract: Ethnic differences in obstructive sleep apnoea (OSA) phenotype may not be limited to obesity and craniofacial factors. The aims of the study were to (i) compare the proportion of Caucasians and Chinese patients with a low respiratory arousal threshold (ArTH) and (ii) explore the influence of anatomical compromise on ArTH.
  
  
  
  Interethnic comparison was conducted between cohorts of Caucasian and Chinese patients from specialist sleep disorder clinics. Polysomnography and craniofacial photography were performed. A low respiratory ArTH was determined by an ArTH score of 2 or above (one point for each: apnoea-hypopnoea index (AHI) < 30/h, nadir oxygen saturation (SaO2) > 82.5%, fractions of hypopnoeas > 58.3%). Anatomical compromise was stratified according to the photographic face width measurement.
  
  
  
  A total of 348 subjects (163 Caucasians and 185 Chinese) were analysed. There was a significantly lower proportion of Chinese patients with moderate-severe OSA (AHI ≥ 15) who had a low ArTH (28.4% vs 48.8%, P = 0.004). This difference remained significant among those with severe OSA (AHI ≥ 30) (2.6% vs 17.1%, P = 0.02). The proportion of moderate-severe OSA Caucasians with a low ArTH was significantly less in those with severe anatomical compromise (36.6% vs 61.0%, P = 0.03), whereas there was no difference in Chinese patients (25.5% vs 31.5%, P = 0.49).
  
  
  
  Compared to Caucasians with severe OSA, a low respiratory ArTh appears to be a less common pathophysiological mechanism in Chinese patients. Caucasians with less severe anatomical compromise exhibit evidence of a lower ArTh, an association which is absent in Chinese patients. Our data suggest that OSA mechanisms may vary across racial groups.
authors.affiliation: Department of Respiratory Medicine, Gosford Hospital, Gosford, New South Wales, Australia.|School of Medicine and Public Health, University of Newcastle, Newcastle, New South Wales, Australia.|Woolcock Institute of Medical Research, University of Sydney, Sydney, New South Wales, Australia.
authors.forename: Richard W W
authors.initials: RWW
authors.lastname: Lee
authors.affiliation: Department of Respiratory and Sleep Medicine, Royal North Shore Hospital, Sydney, New South Wales, Australia.|Charles Perkins Centre, Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia.
authors.forename: Kate
authors.initials: K
authors.lastname: Sutherland
authors.affiliation: Division of Sleep and Circadian Disorders, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.|Department of Allergy, Immunology and Respiratory Medicine and Central Clinical School, The Alfred and Monash University, Melbourne, Victoria, Australia.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Sands
authors.affiliation: Sleep and Circadian Medicine Laboratory, Department of Physiology, Monash University, Melbourne, Victoria, Australia.|School of Psychological Sciences and Monash Institute of Cognitive and Clinical Neurosciences, Monash University, Melbourne, Victoria, Australia.
authors.forename: Bradley A
authors.identifier: 0000-0001-9383-1644
authors.initials: BA
authors.lastname: Edwards
authors.affiliation: Division of Respiratory Medicine, Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong.
authors.forename: Tat On
authors.initials: TO
authors.lastname: Chan
authors.affiliation: Division of Respiratory Medicine, Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong.
authors.forename: Susanna
authors.initials: S
authors.lastname: S S Ng
authors.affiliation: Division of Respiratory Medicine, Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong.
authors.forename: David S
authors.initials: DS
authors.lastname: Hui
authors.affiliation: Department of Respiratory and Sleep Medicine, Royal North Shore Hospital, Sydney, New South Wales, Australia.|Charles Perkins Centre, Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Cistulli
mesh_terms: D000328:Adult; D000368:Aged; D001143:Arousal / Q000502:physiology*; D044466:Asian People; D001315:Australia / Q000208:ethnology; D015331:Cohort Studies; D005260:Female; D006723:Hong Kong / Q000208:ethnology; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D020181:Sleep Apnea, Obstructive / Q000208:ethnology* / Q000503:physiopathology*; D044465:White People
keywords: anatomical compromise; ethnicity; facial anatomy; obstructive sleep apnoea; respiratory arousal threshold