Lipoprotein-associated phospholipase A₂, high-sensitivity C-reactive protein, and risk for incident ischemic stroke in middle-aged men and women in the Atherosclerosis Risk in Communities (ARIC) study

Background: Measurement of inflammatory markers has been reported to identify individuals at increased risk for ischemic stroke. Lipoprotein- associated phospholipase A₂ (Lp-PLA₂) is a proinflammatory enzyme secreted by macrophages. We assessed Lp-PLA₂ and C-reactive protein (CRP) levels along with traditional risk factors to examine their relation to ischemic stroke. Methods: A proportional hazards model was used in prospective case-cohort study of 12 762 apparently healthy middle-aged men and women in the Atherosclerosis Risk in Communities (ARIC) study who were observed for about 6 years. Results: Mean Lp-PLA₂ and CRP levels adjusted for sex, race, and age were higher in the 194 stroke cases than the 766 noncases, whereas low-density lipoprotein cholesterol (LDL-C) level was not significantly different. Both Lp-PLA₂ and CRP levels were associated with ischemic stroke after adjustment for age, sex, and race: hazard ratios were 2.23 for the highest vs the lowest tertile of Lp-PLA₂ and 2.70 for CRP level higher than 3 vs lower than 1 mg/L. In a model that included smoking, systolic hypertension, lipid levels, and diabetes, Lp-PLA₂ and CRP levels in the highest category were associated with hazard ratios of 1.91 (95% confidence interval, 1.15-3.18;P=.01) and 1.87 (95%confidence interval, 1.13-3.10;P=.02), respectively. Individuals with high levels of both CRP and Lp-PLA₂ were at the highest risk after adjusting for traditional risk factors compared with individuals with low levels of both, whereas others were at intermediate risk. Conclusion: Levels of Lp-PLA₂ and CRP may be complementary beyond traditional risk factors in identifying middle-aged individuals at increased risk for ischemic stroke.