Estimated potassium intake and the progression of chronic kidney disease

Abstract

Background: Lower potassium intake is associated with a higher risk of chronic kidney disease (CKD) in the general population. However, there are no stated recommendations on potassium intake in the CKD population owing to limited evidence of benefits from potassium intake and concerns about the risk of hyperkalaemia. This study aimed to investigate the relationship between potassium intake and CKD progression.

Methods: A total of 4314 patients aged 18 years or older in Japan were prospectively followed for 5 years using data from the Fukuoka Kidney Disease Registry study. The patients were divided into quartiles according to estimated potassium intake levels assessed by the Tanaka formula from spot urine samples. The primary outcome was CKD progression, which was defined as a composite of a 1.5-fold increase in creatinine concentrations from baseline and development of end-stage kidney disease. We evaluated the relationship between estimated potassium intake and CKD progression using Cox proportional hazards models.

Results: A total of 1490 patients showed CKD progression during the follow-up with an incidence rate of 90.1/1000 person-years. Patients in the lowest estimated potassium intake quartile had higher hazard ratios for CKD progression than those in the highest quartiles in the multivariable-adjusted Cox models [hazard ratio (95% confidence interval) 1.24 (1.03-1.48)]. Similarly, each 1-standard deviation decrease in estimated potassium intake as a continuous variable was associated with a higher risk of CKD progression [hazard ratio (95% confidence interval) 1.10 (1.03-1.19)].

Conclusions: Lower estimated potassium intake is associated with CKD progression in patients with CKD. Therefore, we recommend adequate potassium intake, taking care not to cause serious adverse events.

Keywords: CKD progression; chronic kidney disease (CKD); nutrition; potassium excretion; potassium intake.

Graphical Abstract

Figure 1:

Event-free survival probabilities for outcomes according to quartiles of estimated potassium intake at baseline. (a) CKD progression, which was defined as a composite of a ≥1.5-fold increase in serum creatinine concentrations from baseline or development of ESKD. (b) A ≥1.5-fold increase in serum creatinine concentrations from baseline. (c) Development of ESKD.

Figure 2:

Multivariable-adjusted restricted cubic spline plots of HRs for CKD progression according to estimated potassium intake at baseline. Solid lines represent HRs and dotted lines represent 95% CIs. Horizontal grey lines correspond to the reference HR (1.0). A histogram of estimated potassium intake is overlaid. The estimated potassium intake of 2000 mg/day was chosen as the reference value. Covariates used in the multivariable model are described in the Materials and methods section.

Figure 3:

Multivariable-adjusted HRs (95% CIs) and interaction effects for CKD progression according to each 1-SD decrease in estimated potassium intake for each subgroup. Covariates used in the multivariable model are described in the Materials and methods section. 1-SD = 446.1 mg/day.