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Am J Med. 2018 Mar;131(3):318.e9-318.e19. doi: 10.1016/j.amjmed.2017.09.026. Epub 2017 Oct 9.

Prognostic Impact of Mild Hypokalemia in Terms of Death and Stroke in the General Population-A Prospective Population Study.

Author information

1
Department of Cardiology, Copenhagen University Hospital of Bispebjerg, Denmark. Electronic address: nickm@dadlnet.dk.
2
Department of Cardiology, Copenhagen University Hospital of Bispebjerg, Denmark.
3
Department of Clinical Sciences, Skåne University Hospital, Lund University, Malmö, Sweden.
4
Department of Cardiology, Copenhagen University Hospital of Bispebjerg, Denmark; Copenhagen City Heart Study, Copenhagen University Hospital of Frederiksberg, Denmark.
5
Copenhagen City Heart Study, Copenhagen University Hospital of Frederiksberg, Denmark.
6
Department of Cardiology, Copenhagen University Hospital of Rigshospitalet, Denmark.

Abstract

BACKGROUND:

Potassium supplementation reduces the risk of cardiovascular mortality and stroke in population studies; however, the prognostic impact of mild hypokalemia in the general population has not been thoroughly investigated. We aimed to investigate associations between mild hypokalemia and endpoints in the general population.

METHODS:

Participants (aged 48-76 years) from the general population study "Copenhagen City Heart Study" (n = 5916) were studied. Participants were divided into groups according to baseline values of plasma potassium (potassium): hypokalemia (<3.7 mmol/L, n = 758), normokalemia (3.7-4.5 mmol/L, n = 4973), and high potassium (>4.5 mmol/L, n = 185). Hypokalemia was further divided as potassium <3.4 mmol/L and 3.4-3.6 mmol/L. The primary endpoints were all-cause mortality and nonfatal validated ischemic stroke. The secondary endpoint was acute myocardial infarction (AMI). We adjusted for conventional risk factors, diuretics, and atrial fibrillation at baseline.

RESULTS:

Mean potassium in the hypokalemic group was 3.5 mmol/L (range, 2.6-3.6 mmol/L) and was associated (P < 0.05) with increased systolic blood pressure, higher CHA2DS2-VASc score, and increased use of diuretics as compared with normokalemia. Baseline atrial fibrillation was equally frequent across groups. Median follow-up-time was 11.9 years (Q1-Q3: 11.4-12.5 years). Hypokalemia was borderline associated with increased stroke risk in a multivariable Cox model (including adjustment for competing risk) as compared with normokalemia (hazard ratio [HR] 1.40; 95% confidence interval [CI], 1.00-1.98). The subgroup with potassium <3.4 mmol/L had higher stroke risk (HR 2.10; 95% CI, 1.19-3.73) and mortality risk (HR 1.32; 95% CI, 1.01-1.74) as compared with normokalemia. Hypokalemia was not associated with AMI, and no increased risk of mortality was seen with concomitant AMI and hypokalemia. No associations were seen with high potassium.

CONCLUSION:

In a general population mild hypokalemia is associated with increased stroke risk and, to a lesser degree, increased mortality risk.

KEYWORDS:

Epidemiology; Hypokalemia; Longitudinal population based cohorts; Mortality; Stroke

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