Plasma selenium and the risk of first stroke in adults with hypertension: a secondary analysis of the China Stroke Primary Prevention Trial

Abstract

ABSTRACT Background Previous studies have indicated that selenium (Se) may play an important role in cardio-cerebrovascular disease. However, the relation between circulating selenium and risk of first stroke remains inconclusive. Objectives We conducted a secondary analysis of the China Stroke Primary Prevention Trial (CSPPT), using a nested case-control design, and aimed to investigate the correlation between Se concentration and first stroke risk in adults with hypertension and examine the potential effect modifiers. Methods In the CSPPT, a total of 20,702 adults with hypertension were randomly assigned to a double-blind daily treatment with either 10 mg enalapril and 0.8 mg folic acid or 10 mg enalapril alone. A total of 618 first stroke cases and 618 controls matched for age, sex, treatment group, and study site were included in this study. Results During a median follow-up duration of 4.5 y (IQR: 4.2–4.6 y), there was a significant inverse association between plasma Se and the risk of first stroke (per SD increment; adjusted OR: 0.81; 95% CI: 0.68, 0.96) and ischemic stroke (per SD increment; adjusted OR: 0.76; 95% CI: 0.62, 0.93). Furthermore, a stronger inverse association between plasma Se and first stroke was observed in participants with higher folate concentrations at baseline [≥7.7 ng/mL (median), adjusted OR: 0.67; 95% CI: 0.54, 0.85, compared with <7.7 ng/mL, adjusted OR: 0.98; 95% CI: 0.80, 1.21; P-interaction = 0.008] and those with higher time-averaged systolic blood pressure (SBP) over the treatment period (≥140 mm Hg, adjusted OR: 0.71; 95% CI: 0.58, 0.86, compared with <140 mm Hg, adjusted OR: 0.96; 95% CI: 0.77, 1.20; P-interaction = 0.023). Conclusions There was a significant inverse association between plasma Se and risk of first stroke in Chinese adults with hypertension, especially among those with higher baseline folate concentrations and those with higher time-averaged SBP over the treatment period. This trial was registered at clinicaltrials.gov as NCT00794885.