Influence of renal function on the association between homocysteine level and risk of ischemic stroke.

We examined whether the association between total homocysteine (tHCY) and risk of ischemic stroke (IS) varies depending on renal function to gain insight into why tHCY-lowering vitamins do not reduce the incidence of cardiovascular disease in clinical trials. We analyzed data from 542 IS patients with large artery atherosclerosis (LAA) or small artery occlusion (SAO) after stratification by estimated glomerular filtration rate (eGFR) to evaluate renal function. We found that tHCY level was positively associated with the occurrence of IS in both LAA (OR: 1.159, 95% CI: 1.074-1.252, P<0.001) and SAO (OR: 1.143, 95% CI: 1.064-1.228, P<0.001) patients and in LAA (OR: 1.135, 95% CI: 1.047-1.230, P=0.002) and SAO (OR: 1.159, 95% CI: 1.060-1.268, P=0.001) subgroups with normal renal function but not in LAA or SAO subgroups with renal insufficiency. eGFR level was positively associated with IS in LAA (OR: 1.022, 95% CI: 1.010-1.034, P<0.001) and SAO (OR: 1.024, 1.012-1.037, P<0.001) subgroups with normal renal function but was negatively associated with IS in LAA (OR: 0.875, 95% CI: 0.829-0.925, P<0.001) and SAO (OR: 0.890, 95% CI: 0.850-0.932, P<0.001) subgroups with renal insufficiency. Folic acid level was negatively associated with IS in LAA (OR: 0.734, 95% CI: 0.606-0.889, P=0.002) and SAO (OR: 0.861, 95% CI: 0.767-0.967, P=0.012) subgroups with renal insufficiency. Therefore, renal function as evaluated by eGFR exerts a significant influence on the association between tHCY and risk of IS.