Cholesterol levels and risk of hemorrhagic stroke: a systematic review and meta-analysis

Abstract

Background and purpose: Cholesterol levels are inconsistently associated with the risk of hemorrhagic stroke. The purpose of this study is to assess their relationships using a meta-analytic approach.

Methods: We searched PubMed and Embase for pertinent articles published in English. Only prospective studies that reported effect estimates with 95% confidential intervals (CIs) of hemorrhagic stroke for ≥3 categories of cholesterol levels, for high and low comparison, or for per 1 mmol/L increment of cholesterol concentrations were included. We used the random-effects model to pool the study-specific results.

Results: Twenty-three prospective studies were included, totaling 1 430 141 participants with 7960 (5.6%) hemorrhagic strokes. In high versus low analysis, the summary relative risk of hemorrhagic stroke was 0.69 (95% CI, 0.59-0.81) for total cholesterol, 0.98 (95% CI, 0.80-1.19) for high-density lipoprotein cholesterol, and 0.62 (95% CI, 0.41-0.92) for low-density lipoprotein cholesterol. In dose-response analysis, the summary relative risk of hemorrhagic stroke for 1 mmol/L increment of total cholesterol was 0.85 (95% CI, 0.80-0.91), for high-density lipoprotein cholesterol was 1.11 (95% CI, 0.99-1.25), and for low-density lipoprotein cholesterol was 0.90 (95% CI, 0.77-1.05). The pooled relative risk for intracerebral hemorrhage was 1.17 (95% CI, 1.02-1.35) for high-density lipoprotein cholesterol.

Conclusions: Total cholesterol level is inversely associated with risk of hemorrhagic stroke. Higher level of low-density lipoprotein cholesterol seems to be associated with lower risk of hemorrhagic stroke. High-density lipoprotein cholesterol level seems to be positively associated with risk of intracerebral hemorrhage.

Keywords: hemorrhagic stroke; high-density lipoprotein cholesterol; intracerebral hemorrhage; low-density lipoprotein cholesterol; meta-analysis; subarachnoid hemorrhage; total cholesterol.