title: Sleep apnea and systemic hypertension: a causal association review.
abstract: OBJECTIVE
  To critically examine the causal association between sleep apnea syndrome and hypertension.
  
  
  METHODS
  A retrospective systematic critique of five epidemiologic studies published in the English literature during 1978 to 1989 identified on Medline and manual literature searches. The evidence was evaluated using the standard observational criteria for causation: strength of association, consistency, dose-response relationship, temporal sequence, specificity, and biologic plausibility.
  
  
  RESULTS
  We found evidence to support a causal association between sleep apnea syndrome and hypertension in consistency and specificity and some evidence to suggest a dose-response relationship. Review of the data dealing with the mechanisms important in the pathogenesis of sleep apnea and hypertension allowed us to advance several theories to provide support for biologic plausibility.
  
  
  CONCLUSIONS
  We concluded that there is a positive association--relative risk estimate between 1.3 and 40--for sleep apnea syndrome and hypertension, but the risk association is unstable. Thus, we believe that there is insufficient data to justify doing polysomnography as part of the routine diagnostic work-up for patients with hypertension.
authors.affiliation: Department of Medicine, St. Michael's Hospital, University of Toronto, Ontario, Canada.
authors.forename: V
authors.initials: V
authors.lastname: Hoffstein
authors.forename: C K
authors.initials: CK
authors.lastname: Chan
authors.forename: A S
authors.initials: AS
authors.lastname: Slutsky
mesh_terms: D015984:Causality; D004812:Epidemiologic Methods; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D006973:Hypertension / Q000209:etiology*; D008297:Male; D012307:Risk Factors; D012891:Sleep Apnea Syndromes / Q000150:complications*