title: Proportion of surgical patients with undiagnosed obstructive sleep apnoea.
abstract: BACKGROUND
  Obstructive sleep apnoea (OSA) affects ~9-24% of the general population, and 90% remain undiagnosed. Those patients with undiagnosed moderate-to-severe OSA may be associated with an increased risk of perioperative complications. Our objective was to evaluate the proportion of surgical patients with undiagnosed moderate-to-severe OSA.
  
  
  METHODS
  After research ethics board approval, patients visiting preoperative clinics were recruited over 4 yr and screened with the STOP-BANG questionnaire. The 1085 patients, who consented, subsequently underwent polysomnography (PSG) (laboratory or portable) before operation. Chart review was conducted in this historical cohort to ascertain the clinical diagnosis of OSA by surgeons and anaesthetists, blinded to the PSG results. The PSG study-identified OSA patients were further classified based on severity using the apnoea-hypopnoea index (AHI) cut-offs.
  
  
  RESULTS
  Of 819 patients, 111 patients had pre-existing OSA and 58% (64/111) were not diagnosed by the surgeons and 15% (17/111) were not diagnosed by the anaesthetists. Among the 708 study patients, PSG showed that 233 (31%) had no OSA, 218 (31%) patients had mild OSA (AHI: 5-15); 148 (21%) had moderate OSA (AHI: 15-30), and 119 (17%) had severe OSA (AHI>30). Before operation, of the 267 patients with moderate-to-severe OSA, 92% (n=245) and 60% (n=159) were not diagnosed by the surgeons and the anaesthetists, respectively.
  
  
  CONCLUSIONS
  We found that anaesthetists and surgeons failed to identify a significant number of patients with pre-existing OSA and symptomatic undiagnosed OSA, before operation. This study may provide an impetus for more diligent case finding of OSA before operation.
authors.affiliation: Department of Anaesthesia, University Health Network, University of Totonto, Toronto, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Singh
authors.forename: P
authors.initials: P
authors.lastname: Liao
authors.forename: S
authors.initials: S
authors.lastname: Kobah
authors.forename: D N
authors.initials: DN
authors.lastname: Wijeysundera
authors.forename: C
authors.initials: C
authors.lastname: Shapiro
authors.forename: F
authors.initials: F
authors.lastname: Chung
mesh_terms: D000368:Aged; D015331:Cohort Studies; D045422:Continuous Positive Airway Pressure; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010361:Patients; D010820:Physicians; D017286:Polysomnography; D011300:Preoperative Care; D018401:Sample Size; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis* / Q000453:epidemiology*; D013514:Surgical Procedures, Operative