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Health effects of obstructive sleep apnoea and the effectiveness of continuous positive airways pressure: a systematic review of the research evidence

BMJ 1997; 314 doi: (Published 22 March 1997) Cite this as: BMJ 1997;314:851
  1. John Wright (j.wright{at}, consultant in epidemiology and public health medicine,a,
  2. Rachel Johns, research development managerb,
  3. Ian Watt, consultant in public health medicinec,
  4. Arabella Melville, research fellowc,
  5. Trevor Sheldon, directorc
  1. a Bradford Royal Infirmary Bradford West Yorkshire BD9 6RJ
  2. b North Yorkshire Health Authority York YO3 4XF
  3. c NHS Centre for Reviews and Dissemination University of York York YOU DD
  1. Correspondence to: Dr Wright
  • Accepted 30 January 1997


Additional data from this article are available on the

Objective: To examine the research evidence for the health consequences of obstructive sleep apnoea and the effectiveness of continuous positive airways pressure.

Design: A systematic review of published research, studies being identified by searching Medline (1966-96), Embase (1974-96), and CINAHL (Cumulative Index to Nursing and Allied Health Literature) (1982-95); scanning citations; and consulting experts. Studies in all languages were considered which either investigated the association between obstructive sleep apnoea in adults and key health outcomes or evaluated the effectiveness of treatment of obstructive sleep apnoea with continuous positive airways pressure in adults.

Main outcome measures: Mortality, systematic hypertension, cardiac arrhythmias, ischaemic heart disease, left ventricular hypertrophy, pulmonary hypertension, stroke, vehicle accidents, measures of daytime sleepiness, and quality of life.

Results: 54 epidemiological studies examined the association between sleep apnoea and health related outcomes. Most were poorly designed and only weak or contradictory evidence was found of an association with cardiac arrhythmias, ischaemic heart disease, cardiac failure, systemic or pulmonary hypertension, and stroke. Evidence of a link with sleepiness and road traffic accidents was stronger but inconclusive. Only one small randomised controlled trial evaluated continuous positive airways pressure. Five non-randomised controlled trials and 38 uncontrolled trials were identified. Small changes in objectively measured daytime sleepiness were consistently found, but improvements in morbidity, mortality, and quality of life indicators were not adequately assessed.

Conclusions: The relevance of sleep apnoea to public health has been exaggerated. The effectiveness of continuous positive airways pressure in improving health outcomes has been poorly evaluated. There is enough evidence suggesting benefit in reducing daytime sleepiness in some patients to warrant large randomised placebo controlled trials of continuous positive airways pressure versus an effective weight reduction programme and other interventions.

Key messages

  • Obstructive sleep apnoea is claimed to be an important cause of premature death and disability

  • There is increasing pressure to provide sleep services for the treatment of patients with sleep apnoea

  • Epidemiological evidence suggests that sleep apnoea causes daytime sleepiness and possibly vehicle accidents

  • Evidence for a causal association between sleep apnoea and other adverse health outcomes is weak

  • There is a paucity of robust evidence for the clinical and cost effectiveness of continuous positive airways pressure in the treatment of most patients with sleep apnoea


  • Funding The initial phase of this review was supported by the Yorkshire Collaborating Centre for Health Services Research.

  • Conflict of interest None.

  • Accepted 30 January 1997
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