Urinary potassium excretion and mortality risk in community-dwelling individuals with and without obesity

Abstract

Background: Potassium intake has been shown to be inversely associated with blood pressure and premature mortality. Previous studies have suggested that the association between potassium intake and blood pressure is modified by obesity, but whether obesity similarly influences the association between potassium intake and mortality is unclear.

Objectives: We investigated whether potassium intake, reflected by 24-h urinary excretion, is associated with all-cause mortality, and explored potential effect modification by obesity.

Methods: We performed a prospective cohort study in community-dwelling individuals. The association between urinary potassium excretion and all-cause mortality was investigated by using multivariable Cox regression. We performed multiplicative interaction analysis and subgroup analyses according to BMI and waist circumference.

Results: In 8533 individuals (50% male), the mean age was 50 ± 13 y, mean urinary potassium excretion was 71 ± 21 mmol/24 h, median BMI (in kg/m2) was 25.6 (IQR: 23.1, 28.4) and mean waist circumference was 89 ± 13 cm. During median follow-up of 18.4 (IQR: 13.5, 18.8) y, 1663 participants died. Low urinary potassium excretion (first compared with third sex-specific quintile) was associated with an increased mortality risk (fully adjusted HR: 1.38; 95% CI: 1.18, 1.61), P < 0.001, irrespective of body dimensions (HR range for all body dimensions: 1.36-1.70, all P < 0.05). High urinary potassium excretion (fifth compared with third quintile) was associated with increased mortality risk in participants with obesity (BMI ≥30; HR: 1.52; CI: 1.00, 2.30), but not in participants without obesity (BMI: <25; HR: 0.89; 95% CI: 0.62, 1.26; P-interaction = 0.001).

Conclusions: Low potassium intake was associated with increased mortality risk in community-dwelling individuals. In individuals with obesity, high potassium intake was also associated with increased mortality risk.

Keywords: body dimension; epidemiology; general population; mortality; nutrition; potassium intake.

FIGURE 1

Associations between urinary potassium excretion and all-cause mortality in 8533 participants. Data were fit by a Cox proportional hazards regression model based on restricted cubic splines (5th, 50th, and 95th percentile knots) and adjusted for age, sex, eGFR, BMI, urinary albumin-to-creatinine excretion, type 2 diabetes, education level, alcohol consumption, smoking, history of CVD, triglyceride HDL ratio, urinary creatinine excretion, urea excretion, sodium excretion, antihypertensive, oral hypoglycemic and lipid lowering drugs. The gray area represents the 95% CI. Linear P = 0.003, nonlinear P < 0.001. CVD, cardiovascular disease; eGFR, estimated glomerular filtration rate.

FIGURE 2

3D plots depicting the multivariable adjusted association between urinary potassium excretion (BMI, A; Waist circumference, B) and all-cause mortality in 8533 participants. Cox proportional hazards regression model was adjusted for age, sex, eGFR, BMI, urinary albumin-to-creatinine excretion, type 2 diabetes, education level, alcohol consumption, smoking, history of CVD, triglyceride HDL ratio, urinary creatinine excretion, urea excretion, sodium excretion, antihypertensive, oral hypoglycemic and lipid lowering drugs. CVD, cardiovascular disease; eGFR, estimated glomerular filtration rate.