Abstract
ObjectiveAsymptomatic carotid stenosis (ACS) is associated with an increased risk of ischaemic stroke and myocardial infarction. Risk scores have been developed to detect individuals at high risk of ACS, thereby enabling targeted screening, but previous external validation showed scope for refinement of prediction by adding additional predictors. The aim of this study was to develop a novel risk score in a large contemporary screened population.MethodsA prediction model was developed for moderate (≥50%) and severe (≥70%) ACS using data from 596 469 individuals who attended screening clinics. Variables that predicted the presence of ≥50% and ≥70% ACS independently were determined using multivariable logistic regression. Internal validation was performed using bootstrapping techniques. Discrimination was assessed using area under the receiver operating characteristic curves (AUROCs) and agreement between predicted and observed cases using calibration plots.ResultsPredictors of ≥50% and ≥70% ACS were age, sex, current smoking, diabetes mellitus, prior stroke/transient ischaemic attack, coronary artery disease, peripheral arterial disease, blood pressure, and blood lipids. Models discriminated between participants with and without ACS reliably, with an AUROC of 0.78 (95% confidence interval [CI] 0.77–0.78) for ≥ 50% ACS and 0.82 (95% CI 0.81–0.82) for ≥ 70% ACS. The number needed to screen in the highest decile of predicted risk to detect one case with ≥50% ACS was 13 and that of ≥70% ACS was 58. Targeted screening of the highest decile identified 41% of cases with ≥50% ACS and 51% with ≥70% ACS.ConclusionThe novel risk model predicted the prevalence of ACS reliably and performed better than previous models. Targeted screening among the highest decile of predicted risk identified around 40% of all cases with ≥50% ACS. Initiation or intensification of cardiovascular risk management in detected cases might help to reduce both carotid related ischaemic strokes and myocardial infarctions.
Highlights
The prevalence of moderate (!50%) and severe (!70%) asymptomatic carotid stenosis (ACS) in the general population is low, with estimates of 2.0% and 0.5%, respectively; population level screening for ACS with duplex ultrasound is not recommended in current guidelines.5e9Risk scores to enable targeted screening of cases in populations with an elevated risk of ACS have been developed.10e14 A previous external validation of these established risk scores showed that the prediction model with the best predictive performance identified a group of cases at high risk of ACS with a number of participants needed to screen (NNS) of 21 to detect one case with !50% ACS when only people in the highest decile of predicted risk were screened.[15]
Data used to develop these risk scores were based on participants who were recruited over two decades ago and important predictors of ACS, such as peripheral arterial disease (PAD), were not included in that model
12.2% of participants were current smokers and 28.2% were former smokers; 8.4% reported a history of diabetes mellitus (DM)
Summary
Risk scores to enable targeted screening of cases in populations with an elevated risk of ACS have been developed.10e14 A previous external validation of these established risk scores showed that the prediction model with the best predictive performance identified a group of cases at high risk of ACS with a number of participants needed to screen (NNS) of 21 to detect one case with !50% ACS when only people in the highest decile of predicted risk were screened.[15] data used to develop these risk scores were based on participants who were recruited over two decades ago and important predictors of ACS, such as peripheral arterial disease (PAD), were not included in that model. A new risk score (the Prevalence of Asymptomatic Carotid Artery Stenosis [PACAS] risk score) was developed in a large contemporary screened population to predict ACS and to further reduce the NNS by targeted screening of those at highest risk of ACS
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More From: European Journal of Vascular & Endovascular Surgery
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