U-shaped Association Between Plasma Magnesium and First Stroke: A Community Based Nested Case-control Study

Abstract

Background: Previous studies on the association between plasma magnesium concentrations and risk of first stroke were limited. We aimed to evaluate the association between plasma magnesium concentrations and the risk of first stroke in a community based Chinese population. Methods: The study sample population was drawn from “H-type Hypertension Prevention and Control Public Service Project” in China. We conducted a nested case–control analysis and matched 1255 cases with an equal number of controls for age ± 1 years, sex and study sites. Conditional logistic regression models was used to estimate the association of plasma magnesium with the risk of stroke and stroke subtypes (ischemic stroke and hemorrhagic strokes). Results: Using restricted cubic splines, there was a U-shaped association of plasma magnesium concentrations with risk of first stroke and ischemic stroke. Compared with the middle tertile (19.14 -< 20.67 mg/L), the multivariate-adjusted ORs (95% confidence interval [CI]) of stroke and ischemic stroke in the lowest tertile plasma magnesium were 1.37 (1.10, 1.70) and 1.36 (1.07, 1.72), in the highest tertile of plasma magnesium were 1.28 (1.03, 1.60) and 1.31 (1.03, 1.67), respectively. Furthermore, a stronger positive association between low tertile of plasma magnesium and first stroke was found in participants with current smoking than without (P-interaction=0.035). No significant effect modifications were observed in subgroup analysis. Conclusions: Our study indicated a U-shaped association between plasma magnesium and first stroke, especially among current smoker.