title: Electro-oculography-based detection of sleep-wake in sleep apnea patients.
abstract: BACKGROUND
  Recently, we have developed a simple method that uses two electro-oculography (EOG) electrodes for the automatic scoring of sleep-wake in normal subjects. In this study, we investigated the usefulness of this method on 284 consecutive patients referred for a suspicion of sleep apnea who underwent a polysomnography (PSG).
  
  
  METHODS
  We applied the AASM 2007 scoring rules. A simple automatic sleep-wake classification algorithm based on 18-45 Hz beta power was applied to the calculated bipolar EOG channel and was compared to standard polysomnography. Epoch by epoch agreement was evaluated.
  
  
  RESULTS
  Eighteen patients were excluded due to poor EOG quality. One hundred fifty-eight males and 108 females were studied, their mean age was 48 (range 17-89) years, apnea-hypopnea index 13 (range 0-96) /h, BMI 29 (range 17-52) kg/m(2), and sleep efficiency 78 (range 0-98) %. The mean agreement in sleep-wake states between EOG and PSG was 85% and the Cohen's kappa was 0.56. Overall epoch-by-epoch agreement was 85%, and the Cohen's kappa was 0.57 with positive predictive value of 91% and negative predictive value of 65%.
  
  
  CONCLUSIONS
  The EOG method can be applied to patients referred for suspicion of sleep apnea to indicate the sleep-wake state.
authors.affiliation: Sleep Laboratory, Finnish Institute of Occupational Health, Topeliuksenkatu 41 a A, 00250, Helsinki, Finland, jussi.virkkala@ttl.fi.
authors.forename: Jussi
authors.initials: J
authors.lastname: Virkkala
authors.forename: Jussi
authors.initials: J
authors.lastname: Toppila
authors.forename: Paula
authors.initials: P
authors.lastname: Maasilta
authors.forename: Adel
authors.initials: A
authors.lastname: Bachour
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004585:Electrooculography / Q000295:instrumentation*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography / Q000295:instrumentation*; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis*; D014851:Wakefulness; D055815:Young Adult