Background: While blood cholesterol level predicts coronary heart disease, whether there is any association with the risk of stroke is unclear. Some, but not all, observational studies suggest that cholesterol level predicts risk of stroke, particularly ischemic stroke. This hypothesis is attractive because ischemic events constitute the vast majority of all strokes and, like coronary heart disease, involve atherogenic processes.
Methods: To investigate whether lipid lowering reduces the risk of stroke, we performed an overview of randomized trials that included more than 36,000 individuals.
Results: The mean reduction in cholesterol level in the treated as compared with the control subjects ranged from 6% to 23%. Those assigned to treatment experienced no significant reduction in all (fatal plus nonfatal) stroke (relative risk, 1.0; 95% confidence interval, 0.8 to 1.2) or fatal stroke (1.1; 0.8 to 1.6).
Conclusions: The confidence interval for fatal stroke is wide, and alternative hypotheses, including either a small protective or harmful effect, cannot be excluded; however, the point estimates are compatible with no benefit of cholesterol lowering on the risk of stroke. Additional large-scale randomized trials assessing total mortality would more definitively address any benefits on stroke, as well as any excess nonvascular causes of mortality, for which risks of cholesterol lowering also remain uncertain.