Higher sodium and lower potassium intakes associated with increased CV risk

Introduction and methods

Background

There are controversial findings on the association between sodium intake and CV risk. Both estimated lower and higher sodium intakes have been linked to increased CV risk [1-4]. This may be due to methodologic limitations, which include inaccurate estimates of individual sodium intakes and reverse causation related to coexisting conditions or changes in health status [5].

Because sodium and potassium are interrelated [6], the associations with CV risk were jointly examined.

In this study, the relationship between sodium and potassium intakes and CV risk were examined by combining individual-level data from studies in healthy populations in which multiple 24-h urine sample were obtained for each participant.

Study design

Individual data from six cohorts were combined. 10,709 Participants who had at least two 24-h urine samples at baseline were included. Sodium and potassium excretions were assessed by averaging the excretions in all available 24-h urine samples per participant.

Primary outcome

The primary outcome was a CV event, defined as the composite of coronary revascularization, fatal or nonfatal MI, or fatal or nonfatal stroke. The primary analysis excluded the first year of follow-up, because dietary information collected close to an event may not reflect habitual sodium intake. Median follow-up was 8.8 years (IQR: 7.6-10.9).

Main results

Sodium results

• Median 24-h sodium excretion was 3270 mg (10th-90th percentile: 2099- 4899), leading to estimated overall daily sodium intake of 3516 mg (10th-90th percentile: 2257-5268).
• When comparing quartile 4 of sodium excretion with quartile 1, HR was 1.60 (95%CI:1.19-2.14).
• A linear association over the range of sodium excretion was observed (P<0.001 for linearity).
• Each additional 100 mg of daily sodium excretion was associated with an 18% increase in CV risk (adjusted HR: 1.18, 95%CI:1.08-1.29).

Potassium results

• The estimated overall daily potassium intake was 3292 mg (10th-90th percentile: 2162-4700).
• When comparing quartile 4 of potassium excretion with quartile 1, HR was 0.69 (95%CI:0.51-0.91).
• There was also a linear trend for potassium excretion and CV risk, with each additional 1000 mg of daily potassium excretion associated with an 18% lower CV risk (HR 0.82, 95%CI:0.72-0.94).

Sodium-potassium ratio results

• When comparing quartile 4 of sodium-potassium ratio with quartile 1, HR was 1.62 (95%CI:1.25-2.10). For each unit increase in the sodium-potassium ratio, there was a 24% increase in CV risk (HR 1.24, 95%CI:1.12-1.37).

Conclusion

References

Find this article online at N Eng J Med