title: Inter-relationships of plasma fibrinogen, low-density lipoprotein cholesterol, cigarette smoking and the prevalence of cardiovascular disease.
abstract: BACKGROUND
  The magnitude of the cardiovascular risk associated with plasma fibrinogen concentration is influenced separately by cigarette smoking and by low-density lipoprotein (LDL) cholesterol levels. The effects of combinations of these factors on risk and the extent to which inclusion of the plasma fibrinogen level further refines the risks associated with smoking and high LDL cholesterol levels are not known.
  
  
  OBJECTIVE
  To determine the inter-relationships among all of the three factors smoking, LDL cholesterol level and fibrinogen level with respect to the occurrence of cardiovascular disease.
  
  
  METHODS
  The study was part of the Edinburgh Artery Study, which was a cross-sectional random sample survey of 1592 men and women aged 55-74 years. The assessment of cardiovascular disease included recall of diagnosis by a doctor of angina or myocardial infarction, intermittent claudication determined by a questionnaire and measurement of ankle systolic blood pressure.
  
  
  RESULTS
  The odds ratio for disease in smokers in the top tertiles of plasma fibrinogen and LDL cholesterol levels was 7.7 (95% confidence interval 3.0-19.8; P < or = 0.001). Neither a multiplicative nor a synergistic effect of the three factors on the odds of disease was observed but the level of each contributed to the risk. For example, in current smokers in the bottom tertile of LDL cholesterol level, the odds of disease were 6.1 (95% confidence interval 2.2-17.0; P < or = 0.001) in the top tertile, 2.9 (95% confidence interval 1.0-8.6; P < or = 0.05) in the middle tertile and 1.6 (95% confidence interval 0.5-4.8; P > 0.05) in the bottom tertile of plasma fibrinogen level. Subjects in the bottom tertile of plasma fibrinogen level did not have significantly elevated (P < 0.05) risks irrespective of LDL cholesterol levels and smoking status.
  
  
  CONCLUSIONS
  The incorporation of plasma fibrinogen level permitted more precise delineation of the odds of disease within categories of smoking and LDL cholesterol concentration. These relationships need to be investigated further in prospective studies.
authors.affiliation: Wolfson Unit for Prevention of Peripheral Vascular Diseases, University of Edinburgh, Department of Public Health Sciences, UK.
authors.forename: F G
authors.initials: FG
authors.lastname: Fowkes
authors.forename: A J
authors.initials: AJ
authors.lastname: Lee
authors.forename: G D
authors.initials: GD
authors.lastname: Lowe
authors.forename: R A
authors.initials: RA
authors.lastname: Riemersma
authors.forename: E
authors.initials: E
authors.lastname: Housley
mesh_terms: D000368:Aged; D002318:Cardiovascular Diseases / Q000453:epidemiology*; D002784:Cholesterol / Q000378:metabolism*; D008078:Cholesterol, LDL / Q000097:blood*; D003430:Cross-Sectional Studies; D005260:Female; D005340:Fibrinogen / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D015995:Prevalence; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology*
chemical_list: D008078:Cholesterol, LDL; D005340:Fibrinogen; D002784:Cholesterol