Association of polygenic risk scores for coronary artery disease with subsequent events amongst established cases

Abstract

BackgroundThere is growing evidence that polygenic risk scores (PRS) can be used to identify individuals at high lifetime risk of coronary artery disease (CAD). Whether they can also be used to stratify risk of subsequent events among those surviving a first CAD event remains uncertain. MethodsUsing two subsamples of UK Biobank, defined at baseline as prevalent CAD (N=10,287) and without CAD (N=393,108), we evaluated associations between a CAD PRS and incident cardiovascular and fatal outcomes, during a median follow up of 7.8 years. ResultsA 1 S.D. higher PRS was associated with increased risk of incident MI in participants without CAD (OR 1.33; 95% C.I. 1.29, 1.38), but the effect estimate was markedly attenuated in those with prevalent CAD (OR 1.15; 95% C.I. 1.06, 1.25); heterogeneity P =0.0012. Additionally, among prevalent CAD cases, we found evidence of an inverse association between the CAD PRS and risk of all-cause death (OR 0.91; 95% C.I. 0.85, 0.98) compared to those without CAD (OR 1.01; 95% C.I. 0.99, 1.03); heterogeneity P =0.0041. A similar inverse association was found for ischaemic stroke (Prevalent CAD (OR 0.78; 95% C.I. 0.67, 0.90); without CAD (OR 1.09; 95% C.I. 1.04, 1.15), heterogeneity P <0.001). ConclusionsBias induced by case stratification and survival into UK Biobank may attenuate, or reverse, associations of polygenic risk scores derived from case-control studies or populations initially free of disease. Polygenic risk scores for subsequent events should be derived from new genome wide association studies conducted in patients with established disease. Key messagesO_LICAD PRS are positively associated with incident myocardial infarction risk amongst established CAD cases. C_LIO_LIHowever, the effect size is attenuated compared to estimates from CAD-free populations. C_LIO_LICAD PRS are inversely associated with mortality and stroke risk amongst established CAD cases. C_LIO_LIThese associations may reflect index event bias induced by stratifying on case status. C_LIO_LIDedicated GWAS of coronary disease progression are required to improve prediction of subsequent event risk. C_LI