Age-distinct predictors of symptomatic cervicocephalic atherosclerosis

Background: Little is known about whether vascular risk factors predispose to atherosclerotic stroke depending on age. We evaluated predictors of large vessel atherosclerotic stroke (LVAS) stratified by age in two geographically and racially distinct study populations. Methods: Data collected over a 4-year period in prospectively maintained registries on 3,053 subjects with ischemic cerebrovascular events were analyzed: 1,982 patients from a hospital in South Korea and 1,071 patients admitted to a hospital in Los Angeles, Calif., USA. Independent vascular risk factor associations with LVAS mechanism were evaluated in three groups stratified by age (years) at symptom onset: young (≤50 years), older (51-75 years), and oldest (>75 years). Results: Altogether at both study sites, 972 (31.8%) patients had LVAS mechanism, of whom 391 (40.2%) were female. Risk factor profiles were not significantly different between LVAS versus other stroke mechanisms. Among young patients, after adjusting for covariates, current smoking was the only predictor of atherosclerotic stroke at both Korean (OR 2.04; 95% CI: 1.13-3.69) and Californian sites (OR 4.78, 95% CI 1.54-14.89), while the metabolic syndrome was the only predictor of atherosclerotic stroke among the older patients (OR 1.58, 95% CI 1.17-2.12 for Korean; OR 1.75, 95% CI 1.07-2.84 for Californian), but not in the young or oldest groups. Conclusions: Across race and region, the estimated impact of vascular risk factors for LVAS varies by age, and this is most prominently seen among persons of less than 76 years of age. Some risk factors have an early effect (smoking) and others an effect that plays out over time.