title: Improvement in prediction of coronary heart disease risk over conventional risk factors using SNPs identified in genome-wide association studies.
abstract: OBJECTIVE
  We examined whether a panel of SNPs, systematically selected from genome-wide association studies (GWAS), could improve risk prediction of coronary heart disease (CHD), over-and-above conventional risk factors. These SNPs have already demonstrated reproducible associations with CHD; here we examined their use in long-term risk prediction.
  
  
  METHODS
  SNPs identified from meta-analyses of GWAS of CHD were tested in 840 men and women aged 55-75 from the Edinburgh Artery Study, a prospective, population-based study with 15 years of follow-up. Cox proportional hazards models were used to evaluate the addition of SNPs to conventional risk factors in prediction of CHD risk. CHD was classified as myocardial infarction (MI), coronary intervention (angioplasty, or coronary artery bypass surgery), angina and/or unspecified ischaemic heart disease as a cause of death; additional analyses were limited to MI or coronary intervention. Model performance was assessed by changes in discrimination and net reclassification improvement (NRI).
  
  
  RESULTS
  There were significant improvements with addition of 27 SNPs to conventional risk factors for prediction of CHD (NRI of 54%, P<0.001; C-index 0.671 to 0.740, P = 0.001), as well as MI or coronary intervention, (NRI of 44%, P<0.001; C-index 0.717 to 0.750, P = 0.256). ROC curves showed that addition of SNPs better improved discrimination when the sensitivity of conventional risk factors was low for prediction of MI or coronary intervention.
  
  
  CONCLUSIONS
  There was significant improvement in risk prediction of CHD over 15 years when SNPs identified from GWAS were added to conventional risk factors. This effect may be particularly useful for identifying individuals with a low prognostic index who are in fact at increased risk of disease than indicated by conventional risk factors alone.
authors.affiliation: Centre for Population Health Sciences, Medical School, Teviot Place, University of Edinburgh, Edinburgh, United Kingdom. J.Bolton@ed.ac.uk
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Bolton
authors.forename: Marlene C W
authors.initials: MC
authors.lastname: Stewart
authors.forename: James F
authors.initials: JF
authors.lastname: Wilson
authors.forename: Niall
authors.initials: N
authors.lastname: Anderson
authors.forename: Jackie F
authors.initials: JF
authors.lastname: Price
mesh_terms: D000368:Aged; D003327:Coronary Disease / Q000235:genetics*; D005260:Female; D055106:Genome-Wide Association Study; D006801:Humans; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D012307:Risk Factors