title: The effect of CPAP in normalizing daytime sleepiness, quality of life, and neurocognitive function in patients with moderate to severe OSA.
abstract: OBJECTIVE
  The study aimed to document the neurobehavioral outcomes of patients referred to and treated by a sleep medicine service for moderate to severe obstructive sleep apnea (OSA). In particular, we aimed to establish the proportion of patients who, while appearing to have optimal continuous positive airway pressure (CPAP) adherence, did not normalize their daytime sleepiness or neurocognitive function after 3 months of CPAP therapy despite effective control of OSA.
  
  
  METHODS
  Multicenter clinical-effectiveness study.
  
  
  METHODS
  Three academic sleep centers in Australia.
  
  
  METHODS
  Patients referred to a sleep medicine service with moderate to severe OSA (n = 174).
  
  
  METHODS
  CPAP.
  
  
  RESULTS
  Participants were assessed pretreatment and again after 3 months of CPAP therapy. At the beginning and at the conclusion of the trial, participants completed a day of testing that included measures of objective and subjective daytime sleepiness, neurocognitive function, and quality of life. In patients with symptomatic moderate to severe OSA (i.e., apnea-hypopnea index > 30/h), we found a treatment dose-response effect for CPAP in terms of Epworth Sleepiness Scale scores (P < 0.001). Several key indexes of neurobehavior (e.g., Functional Outcomes of Sleep Questionnaire, Epworth Sleepiness Scale) currently used to assess treatment response failed to normalize in a substantial group of patients after 3 months of CPAP treatment, even in those who were maximally compliant with treatment. Forty percent of patients in this trial had an abnormal Epworth Sleepiness Scale score at the conclusion of the trial. In addition, we showed no dose-response effect with the Maintenance of Wakefulness Test, raising doubts as to the clinical utility of the Maintenance of Wakefulness Test in assessing treatment response to CPAP in patients with OSA.
  
  
  CONCLUSIONS
  Our study suggests that a greater percentage of patients achieve normal functioning with longer nightly CPAP duration of use, but a substantial proportion of patients will not normalize neurobehavioral responses despite seemingly adequate CPAP use. It is thus crucial to adequately assess patients after CPAP therapy and seek alternate etiologies and treatments for any residual abnormalities.
authors.affiliation: Adelaide Institute for Sleep Health, Repatriation General Hospital, Daw Park, South Australia, Australia. nick.antic@health.sa.gov.au
authors.forename: Nick A
authors.initials: NA
authors.lastname: Antic
authors.forename: Peter
authors.initials: P
authors.lastname: Catcheside
authors.forename: Catherine
authors.initials: C
authors.lastname: Buchan
authors.forename: Michael
authors.initials: M
authors.lastname: Hensley
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Naughton
authors.forename: Sharn
authors.initials: S
authors.lastname: Rowland
authors.forename: Bernadette
authors.initials: B
authors.lastname: Williamson
authors.forename: Samantha
authors.initials: S
authors.lastname: Windler
authors.forename: R Doug
authors.initials: RD
authors.lastname: McEvoy
mesh_terms: D003071:Cognition; D045422:Continuous Positive Airway Pressure; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010349:Patient Compliance; D011788:Quality of Life / Q000523:psychology; D012890:Sleep; D020181:Sleep Apnea, Obstructive / Q000523:psychology / Q000628:therapy*; D011795:Surveys and Questionnaires; D016896:Treatment Outcome; D014851:Wakefulness