title: Disturbed sleep among COPD patients is longitudinally associated with mortality and adverse COPD outcomes.
abstract: OBJECTIVE
  To investigate the cross-sectional association between COPD severity and disturbed sleep and the longitudinal association between disturbed sleep and poor health outcomes.
  
  
  METHODS
  Ninety eight adults with spirometrically-confirmed COPD were recruited through population-based, random-digit telephone dialing. Sleep disturbance was evaluated using a 4-item scale assessing insomnia symptoms as: difficulty falling asleep, nocturnal awakening, morning tiredness, and sleep duration adequacy. COPD severity was quantified by: FEV(1) and COPD Severity Score, which incorporates COPD symptoms, requirement for COPD medications and oxygen, and hospital-based utilization. Subjects were assessed one year after baseline to determine longitudinal COPD exacerbations and emergency utilization and were followed for a median 2.4 years to assess all-cause mortality.
  
  
  RESULTS
  Sleep disturbance was cross-sectionally associated with cough, dyspnea, and COPD Severity Score, but not FEV(1). In multivariable logistic regression, controlling for sociodemographics and body-mass index, sleep disturbance longitudinally predicted both incident COPD exacerbations (OR=4.7; p=0.018) and respiratory-related emergency utilization (OR=11.5; p=0.004). In Cox proportional hazards analysis, controlling for the same covariates, sleep disturbance predicted poorer survival (HR=5.0; p=0.013). For all outcomes, these relationships persisted after also controlling for baseline FEV(1) and COPD Severity Score.
  
  
  CONCLUSIONS
  Disturbed sleep is cross-sectionally associated with worse COPD and is longitudinally predictive of COPD exacerbations, emergency health care utilization, and mortality.
authors.affiliation: Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of California, San Francisco, USA. omachi@ucsf.edu
authors.forename: Theodore A
authors.initials: TA
authors.lastname: Omachi
authors.forename: Paul D
authors.initials: PD
authors.lastname: Blanc
authors.forename: David M
authors.initials: DM
authors.lastname: Claman
authors.forename: Hubert
authors.initials: H
authors.lastname: Chen
authors.forename: Edward H
authors.initials: EH
authors.lastname: Yelin
authors.forename: Laura
authors.initials: L
authors.lastname: Julian
authors.forename: Patricia P
authors.initials: PP
authors.lastname: Katz
mesh_terms: D000368:Aged; D003430:Cross-Sectional Studies; D004632:Emergency Medical Services / Q000706:statistics & numerical data; D005260:Female; D005541:Forced Expiratory Volume; D006304:Health Status; D006801:Humans; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D016016:Proportional Hazards Models; D011569:Psychiatric Status Rating Scales; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications* / Q000401:mortality / Q000503:physiopathology / Q000628:therapy; D012720:Severity of Illness Index; D012893:Sleep Wake Disorders / Q000150:complications* / Q000401:mortality