Apolipoprotein A1, B levels, and their ratio and the risk of a first stroke: a meta-analysis and case–control study

The associations of levels of apolipoprotein A1 (ApoA1) and apolipoprotein B and ApoB/A1 ratio and risk of a first stroke have not been reliably documented. We performed a meta-analysis to summarize the relationships and confirmed them in a case–control study. We identified relevant publications in PubMed and Embase databases up to June 1, 2015. A Dersimonian-Laird random effects model was used to compute summary relative risks (RRs) and 95 % confidence intervals (CIs). A case–control study was conducted in a southern Chinese population. We included 8 cohort and 4 case–control studies (222,774 subjects; 10,032 first stroke events) in the meta-analysis. Reduced ApoA1 level and increased ApoB level and ApoB/A1 ratio was associated with a first stroke in cohort studies (RR 0.86 [95 % CI 0.79–0.94], 1.66 [1.62–1.69], and 1.66 [1.63–1.70], respectively) and reduced ApoA1 level and increased ApoB/A1 ratio in case–control studies (0.68 [0.47–0.99] and 1.76 [1.50–2.06], respectively). When stratified by stroke type in cohort studies, the RR for ischemic stroke was 0.83 (0.76–0.90), 1.36 (1.32–1.40), and 1.38 (1.35–1.42) for the 3 factors, respectively. In our case–control study (1013 cases; 1029 controls), the OR for a first ischemic stroke was 0.83 (0.74–0.92), 1.33 (1.18–1.48) and 2.10 (1.76–2.51), respectively, with increased ApoA1 level associated with hemorrhagic stroke (1.37 [1.06–1.78]). Meta-analysis suggests that reduced ApoA1 level and increased ApoB level and ApoB/A1 ratio are risk factors for a first ischemic but not hemorrhagic stroke. Elevated ApoA1 level may be a risk factor for a first hemorrhagic stroke.