Lipoprotein-Associated Phospholipase A2 Activity and Mass as Independent Risk Factor of Stroke: A Meta-Analysis

BACKGROUND: The association between lipoprotein-associated phospholipase A2 (Lp-PLA2) and stroke risk is inconsistent. We conducted a meta-analysis to determine whether elevated Lp-PLA2 is a risk factor for stroke. METHODS: Studies were included if they reported Lp-PLA2 mass and/or activity levels and adjusted risk estimates of stroke. The primary outcome was overall stroke incidence. The combined results were shown as relative risks (RRs) with 95% confidence intervals (CI) for per 1 standard deviation (SD) higher value of Lp-PLA2 and the highest versus lowest Lp-PLA2 category. RESULTS: Twenty-two studies involving 157,693 participants were included for analysis. After adjusting for conventional risk factors, the RRs for overall stroke with 1 SD higher Lp-PLA2 activity and mass were 1.07 (95% CI 1.02–1.13) and 1.11 (95% CI 1.04–1.19), respectively. The RRs of ischemic stroke with 1 SD higher Lp-PLA2 activity and mass were 1.08 (95% CI 1.01–1.15) and 1.11 (95% CI 1.02–1.22), respectively. When comparing the highest and lowest levels of Lp-PLA2, the RRs of stroke for Lp-PLA2 activity and mass were 1.26 (95% CI 1.03–1.54) and 1.56 (95% CI 1.21–2.00), respectively. Finally, when comparing the highest and lowest levels of Lp-PLA2, the pooled RRs of ischemic stroke for Lp-PLA2 activity and mass were 1.29 (95% CI 1.07–1.56) and 1.68 (95% CI 1.12–2.53), respectively. CONCLUSIONS: Elevated baseline Lp-PLA2 levels, detected either by activity or mass, are associated with increased stroke risk.