title: Long-term effects of nasal continuous positive airway pressure therapy on cardiovascular outcomes in sleep apnea syndrome.
abstract: BACKGROUND
  Obstructive sleep apnea syndrome (OSAS) has been associated with increased morbidity and mortality, principally from cardiovascular disease, but the impact of nasal continuous positive airway pressure (CPAP) therapy is unclear.
  
  
  METHODS
  We performed a long-term follow-up study of 168 patients with OSAS who had begun receiving CPAP therapy at least 5 years previously, most of whom had been prospectively followed up, having been the subject of an earlier report on cardiovascular risk factors in OSAS patients. The average follow-up period was 7.5 years. We compared the cardiovascular outcomes of those patients who were intolerant of CPAP (untreated group, 61 patients) with those continuing CPAP therapy (107 patients).
  
  
  RESULTS
  CPAP-treated patients had a higher median apnea-hypopnea index score than the untreated group (48.3 [interquartile range (IQR), 33.6 to 66.4] vs 36.7 [IQR, 27.4 to 55], respectively; p = 0.02), but age, body mass index, and time since diagnosis were similar. Deaths from cardiovascular disease were more common in the untreated group than in the CPAP-treated group during follow-up (14.8% vs 1.9%, respectively; p = 0.009 [log rank test]), but no significant differences were found in the development of new cases of hypertension, cardiac disorder, or stroke. Total cardiovascular events (ie, death and new cardiovascular disease combined) were more common in the untreated group than in the CPAP-treated group (31% vs 18%, respectively; p < 0.05).
  
  
  CONCLUSIONS
  The data support a protective effect of CPAP therapy against death from cardiovascular disease in patients with OSAS.
authors.affiliation: Respiratory Sleep Disorders Unit, St. Vincent's University Hospital, Elm Park, Dublin 4, Ireland.
authors.forename: Liam S
authors.initials: LS
authors.lastname: Doherty
authors.forename: John L
authors.initials: JL
authors.lastname: Kiely
authors.forename: Valerie
authors.initials: V
authors.lastname: Swan
authors.forename: Walter T
authors.initials: WT
authors.lastname: McNicholas
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D002318:Cardiovascular Diseases / Q000209:etiology / Q000401:mortality* / Q000517:prevention & control*; D016022:Case-Control Studies; D045422:Continuous Positive Airway Pressure / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D010349:Patient Compliance; D017286:Polysomnography; D011336:Probability; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012016:Reference Values; D018570:Risk Assessment; D012720:Severity of Illness Index; D012737:Sex Factors; D012891:Sleep Apnea Syndromes / Q000150:complications* / Q000175:diagnosis / Q000628:therapy*; D015996:Survival Rate; D016896:Treatment Outcome