Meta-Analysis of Potassium Intake and the Risk of Stroke

Abstract

Background: The possibility that lifestyle factors such as diet, specifically potassium intake, may modify the risk of stroke has been suggested by several observational cohort studies, including some recent reports. We performed a systematic review and meta-analysis of existing studies and assessed the dose-response relation between potassium intake and stroke risk.

Methods and results: We reviewed the observational cohort studies addressing the relation between potassium intake, and incidence or mortality of total stroke or stroke subtypes published through August 6, 2016. We carried out a meta-analysis of 16 cohort studies based on the relative risk (RR) of stroke comparing the highest versus lowest intake categories. We also plotted a pooled dose-response curve of RR of stroke according to potassium intake. Analyses were performed with and without adjustment for blood pressure. Relative to the lowest category of potassium intake, the highest category of potassium intake was associated with a 13% reduced risk of stroke (RR=0.87, 95% CI 0.80-0.94) in the blood pressure-adjusted analysis. Summary RRs tended to decrease when original estimates were unadjusted for blood pressure. Analysis for stroke subtypes yielded comparable results. In the spline analysis, the pooled RR was lowest at 90 mmol of potassium daily intake (RRs=0.78, 95% CI 0.70-0.86) in blood pressure-adjusted analysis, and 0.67 (95% CI 0.57-0.78) in unadjusted analysis.

Conclusions: Overall, this dose-response meta-analysis confirms the inverse association between potassium intake and stroke risk, with potassium intake of 90 mmol (≈3500 mg)/day associated with the lowest risk of stroke.

Keywords: cohort studies; meta‐analysis; potassium; stroke.

Figure 1

Flow chart summarizing study identification and selection. Box 1 shows details of research strategy.

Figure 2

Funnel plot for publication bias for the observational cohort studies included in the meta‐analysis. Long‐dash line shows fitted line corresponding to the regression test for funnel‐plot asymmetry proposed by Egger.

Figure 3

Meta‐analysis of the relative risk (RR), with 95% CI of stroke in observational cohort studies, according to the covariates included in multivariate modeling. RRs from all studies using the “most adjusted model” (A) and the “blood pressure–unadjusted model” (B), and from the studies reporting both blood pressure–adjusted and unadjusted estimates (C).

Figure 4

Meta‐analysis of the relative risk (RR), with 95% CI of stroke in observational cohort studies according to category of baseline dietary potassium intake (<90, ≥90 to <120, ≥120 mmol/day). Estimates are from the most‐adjusted multivariate models with (A) and without (B) adjustment for blood pressure.

Figure 5

Meta‐analysis of the relative risk (RR) with 95% CI of stroke in observational cohort studies according to stroke subtype (ischemic and hemorrhagic). Estimates are from the “most adjusted model” (A) and from the “blood pressure–unadjusted model” (B).

Figure 6

Pooled dose–response association between potassium intake and risk of stroke (solid line) in a meta‐analysis modeling potassium intake with restricted cubic splines in a multivariate random‐effects model, with (A) and without (B) adjustment for blood pressure. The relative risks are plotted on the log scale, with 25 mmol of daily potassium intake serving as referent category. Dashed lines represent the 95% CI for the spline model.