Lower serum potassium associated with increased mortality in dialysis patients: A nationwide prospective observational cohort study in Korea

PLoS One. 2017 Mar 6;12(3):e0171842. doi: 10.1371/journal.pone.0171842. eCollection 2017.

Abstract

Background: Abnormal serum potassium concentration has been suggested as a risk factor for mortality in patients undergoing dialysis patients. We investigated the impact of serum potassium levels on survival according to dialysis modality.

Methods: A nationwide, prospective, observational cohort study for end stage renal disease patients has been ongoing in Korea since August 2008. Our analysis included patients whose records contained data regarding serum potassium levels. The relationship between serum potassium and mortality was analyzed using competing risk regression.

Results: A total of 3,230 patients undergoing hemodialysis (HD, 64.3%) or peritoneal dialysis (PD, 35.7%) were included. The serum potassium level was significantly lower (P < 0.001) in PD (median, 4.5 mmol/L; interquartile range, 4.0-4.9 mmol/L) than in HD patients (median, 4.9 mmol/L; interquartile range, 4.5-5.4 mmol/L). During 4.4 ± 1.7 years of follow-up, 751 patients (23.3%) died, mainly from cardiovascular events (n = 179) and infection (n = 120). In overall, lower serum potassium level less than 4.5 mmol/L was an independent risk factor for mortality after adjusting for age, comorbidities, and nutritional status (sub-distribution hazard ratio, 1.30; 95% confidence interval 1.10-1.53; P = 0.002). HD patients showed a U-shaped survival pattern, suggesting that both lower and higher potassium levels were deleterious, although insignificant. However, in PD patients, only lower serum potassium level (<4.5 mmol/L) was an independent predictor of mortality (sub-distribution hazard ratio, 1.35; 95% confidence interval 1.00-1.80; P = 0.048).

Conclusion: Lower serum potassium levels (<4.5 mmol/L) occur more commonly in PD than in HD patients. It represents an independent predictor of survival in overall dialysis, especially in PD patients. Therefore, management of dialysis patients should focus especially on reducing the risk of hypokalemia, not only that of hyperkalemia.

Publication types

  • Multicenter Study
  • Observational Study

MeSH terms

  • Cause of Death
  • Female
  • Humans
  • Incidence
  • Kidney Failure, Chronic / blood*
  • Kidney Failure, Chronic / epidemiology
  • Kidney Failure, Chronic / mortality*
  • Kidney Failure, Chronic / therapy
  • Male
  • Middle Aged
  • Potassium / blood*
  • Proportional Hazards Models
  • Prospective Studies
  • Renal Dialysis / mortality*
  • Republic of Korea / epidemiology

Substances

  • Potassium

Grant support

This research was supported by a grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (grant number: HC15C1129).