title: Validation study of a portable monitoring device for identifying OSA in a symptomatic patient population.
abstract: OBJECTIVE
  Obstructive sleep apnoea syndrome (OSAS) is a common disorder associated with early atherosclerosis, diabetes mellitus, ischaemic heart disease and cerebrovascular disease. The gold standard for confirming OSAS is based on an attended overnight polysomnography (PSG) in a sleep laboratory; however lack of health-care resources creates long waiting times for patient access to this diagnostic test. This study evaluated the ability of a portable sleep-monitoring device to identify patients in Hong Kong with suspected OSAS.
  
  
  METHODS
  Patients with symptoms of OSAS were invited to use the ARES (apnoea risk evaluation system) concurrently with an attended inpatient PSG. Several sets of AHI were generated by the ARES provider based on different oxygen desaturation criteria and surrogate parameters of arousal. The results were compared against PSG to determine the optimal sensitivity and specificity.
  
  
  RESULTS
  There were 141 patients who completed the study successfully. Results of AHI from the ARES study were presented in the order of different scoring criteria--4% oxygen desaturation alone, obstructive events with 3% oxygen desaturation and obstructive events with 1% desaturation plus surrogate arousal criteria. The sensitivity was 0.84 (95% confidence interval (CI): 0.77-0.90), 0.89 (95% CI: 0.89-0.94) and 0.97 (95% CI: 0.94-0.99), respectively. The specificity was 1, 1 and 0.63 (95% CI: 0.55-0.71), respectively. The receiver operating curve had an area of 0.96, 0.97 and 0.98, respectively. The kappa coefficient varied from 0.24 to 0.55 for agreement of severity between PSG and ARES. The likelihood ratio positive and the likelihood ratio negative were 2.61, infinity, infinity and 0.16, 0.11, 0.05, respectively, in the order of oxygen desaturation described earlier.
  
  
  CONCLUSIONS
  The ARES device has reasonable sensitivity and specificity for diagnosing severe OSAS in symptomatic Chinese patients. There is moderate agreement between ARES and PSG in the diagnosis of severe disease, but less agreement in patients with mild/moderate disease.
authors.affiliation: Respiratory Medicine Division, Department of Medicine and Therapeutics, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Kin-Wang
authors.initials: KW
authors.lastname: To
authors.forename: Wing-Chi
authors.initials: WC
authors.lastname: Chan
authors.forename: Tat-On
authors.initials: TO
authors.lastname: Chan
authors.forename: Alvin
authors.initials: A
authors.lastname: Tung
authors.forename: Jenny
authors.initials: J
authors.lastname: Ngai
authors.forename: Susanna
authors.initials: S
authors.lastname: Ng
authors.forename: Kah-Lin
authors.initials: KL
authors.lastname: Choo
authors.forename: David S
authors.initials: DS
authors.lastname: Hui
mesh_terms: D000328:Adult; D005260:Female; D006723:Hong Kong; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000295:instrumentation* / Q000379:methods; D017286:Polysomnography / Q000295:instrumentation* / Q000379:methods; D011237:Predictive Value of Tests; D012307:Risk Factors; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis*