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Background: The aetiology of ischaemic heart disease (IHD) is complex and is influenced by a spectrum of environmental factors and susceptibility genes. Traditional statistical modelling considers such factors to act independently in an additive manner. The Patient Rule-Induction Method (PRIM) is a multi-model building strategy for evaluating risk attributable to context-dependent gene and environmental effects., Methods: PRIM was applied to 9073 participants from the prospective Copenhagen City Heart Study (CCHS). Gender-specific cumulative incidences were estimated for subgroups defined by categories of age, smoking, hypertension, diabetes, body mass index, total cholesterol, high-density lipoprotein cholesterol and triglycerides and by 94 single nucleotide variants (SNVs).Cumulative incidences for subgroups were validated using an independently ascertained sample of 58 240 participants from the Copenhagen General Population Study (CGPS)., Results: In the CCHS the overall cumulative incidences were 0.17 in women and 0.21 in men. PRIM identified six and four mutually exclusive subgroups in women and men, respectively, with cumulative incidences of IHD ranging from 0.02 to 0.34. Cumulative incidences of IHD generated by PRIM in the CCHS were validated in four of the six subgroups of women and two of the four subgroups of men in the CGPS., Conclusions: PRIM identified high-risk subgroups characterized by specific contexts of selected values of traditional risk factors and genetic variants. These subgroups were validated in an independently ascertained cohort study. Thus, a multi-model strategy may identify groups of individuals with substantially higher risk of IHD than the overall risk for the general population., (© The Author 2014; all rights reserved. Published by Oxford University Press on behalf of the International Epidemiological Association.)

Background: Epidemiologically, high-density lipoprotein (HDL) cholesterol levels associate inversely with risk of ischemic cardiovascular disease. Whether this is a causal relation is unclear., Methods: We studied 10,281 participants in the Copenhagen City Heart Study (CCHS) and 50,523 participants in the Copenhagen General Population Study (CGPS), of which 991 and 1,693 participants, respectively, had developed myocardial infarction (MI) by August 2010. Participants in the CCHS were genotyped for all six variants identified by resequencing lecithin-cholesterol acyltransferase in 380 individuals. One variant, S208T (rs4986970, allele frequency 4%), associated with HDL cholesterol levels in both the CCHS and the CGPS was used to study causality of HDL cholesterol using instrumental variable analysis., Results: Epidemiologically, in the CCHS, a 13% (0.21 mmol/liter) decrease in plasma HDL cholesterol levels was associated with an 18% increase in risk of MI. S208T associated with a 13% (0.21 mmol/liter) decrease in HDL cholesterol levels but not with increased risk of MI or other ischemic end points. The causal odds ratio for MI for a 50% reduction in plasma HDL cholesterol due to S208T genotype in both studies combined was 0.49 (0.11-2.16), whereas the hazard ratio for MI for a 50% reduction in plasma HDL cholesterol in the CCHS was 2.11 (1.70-2.62) (P(comparison) = 0.03)., Conclusion: Low plasma HDL cholesterol levels robustly associated with increased risk of MI but genetically decreased HDL cholesterol did not. This may suggest that low HDL cholesterol levels per se do not cause MI.

Context: Epidemiologically, levels of high-density lipoprotein (HDL) cholesterol and its major protein constituent, apolipoprotein A-I (apoA-I), are inversely related to risk of ischemic heart disease (IHD)., Objective: We tested whether common genetic variation in the apolipoprotein A1 gene (APOA1) contributes to apoA-I and HDL cholesterol levels and risk of IHD in the general population., Design: We resequenced the regulatory and coding regions of APOA1 in 190 individuals from the Copenhagen City Heart Study with the lowest 1% (n=95) and highest 1% (n=95) apoA-I levels. Two single-nucleotide polymorphisms (SNPs) were subsequently genotyped in the Copenhagen City Heart Study (n=10,273) and in 2361 cases with IHD (the Copenhagen Ischemic Heart Disease Study)., Results: In total, 13 genetic variants were identified. Three SNPs, g.-560A→C, g.-151C→T, and *181A→G, determined a haplotype that differed between high and low apoA-I groups (6 vs. 1%, P=0.002). Genotype combinations of two SNPs, the g.-560A→C (tagging the g.-560A→C/g.-151C→T/*181A→G haplotype) and g.-310G→A (situated near a potential functional promoter site), were associated with increases in apoA-I and HDL cholesterol levels of up to 6.6 and 8.5%, respectively, resulting in theoretically predicted reductions in risk of 9 and 8% for IHD and 14 and 12% for myocardial infarction (MI). Despite this, these same genotype combinations were not associated with decreased risk of IHD or MI., Conclusion: Common genetic variation in APOA1 associated with increased apoA-I and HDL cholesterol levels did not associate with decreased risk of IHD or MI.