title: Association of sleep-disordered breathing and the occurrence of stroke.
abstract: BACKGROUND
  Sleep-disordered breathing has been linked to stroke in previous studies. However, these studies either used surrogate markers of sleep-disordered breathing or could not, due to cross-sectional design, address the temporal relationship between sleep-disordered breathing and stroke.
  
  
  OBJECTIVE
  To determine whether sleep-disordered breathing increases the risk for stroke.
  
  
  METHODS
  We performed cross-sectional and longitudinal analyses on 1,475 and 1,189 subjects, respectively, from the general population. Sleep-disordered breathing was defined by the apnea-hypopnea index (frequency of apneas and hypopneas per hour of sleep) obtained by attended polysomnography. The protocol, including polysomnography, risk factors for stroke, and a history of physician-diagnosed stroke, was repeated at 4-yr intervals.
  
  
  RESULTS
  In the cross-sectional analysis, subjects with an apnea-hypopnea index of 20 or greater had increased odds for stroke (odds ratio, 4.33; 95% confidence interval, 1.32-14.24; p = 0.02) compared with those without sleep-disordered breathing (apnea-hypopnea index, <5) after adjustment for known confounding factors. In the prospective analysis, sleep-disordered breathing with an apnea-hypopnea index of 20 or greater was associated with an increased risk of suffering a first-ever stroke over the next 4 yr (unadjusted odds ratio, 4.31; 95% confidence interval, 1.31-14.15; p = 0.02). However, after adjustment for age, sex, and body mass index, the odds ratio was still elevated, but was no longer significant (3.08; 95% confidence interval, 0.74-12.81; p = 0.12).
  
  
  CONCLUSIONS
  These data demonstrate a strong association between moderate to severe sleep-disordered breathing and prevalent stroke, independent of confounding factors. They also provide the first prospective evidence that sleep-disordered breathing precedes stroke and may contribute to the development of stroke.
authors.affiliation: Toronto General Hospital/University Health Network, 9N-943, 200 Elizabeth Street, Toronto, ON M5G 2C4, Canada.
authors.forename: Michael
authors.initials: M
authors.lastname: Arzt
authors.forename: Terry
authors.initials: T
authors.lastname: Young
authors.forename: Laurel
authors.initials: L
authors.lastname: Finn
authors.forename: James B
authors.initials: JB
authors.lastname: Skatrud
authors.forename: T Douglas
authors.initials: TD
authors.lastname: Bradley
mesh_terms: D000328:Adult; D016001:Confidence Intervals; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D017286:Polysomnography; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors; D012891:Sleep Apnea Syndromes / Q000150:complications* / Q000453:epidemiology / Q000503:physiopathology; D020521:Stroke / Q000453:epidemiology / Q000209:etiology* / Q000503:physiopathology; D014922:Wisconsin / Q000453:epidemiology