title: Lower serum potassium associated with increased mortality in dialysis patients: A nationwide prospective observational cohort study in Korea.
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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea.
authors.forename: Sunhwa
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea.
authors.forename: Eunjeong
authors.initials: E
authors.lastname: Kang
authors.affiliation: Department of Internal Medicine, Dongguk University Gyeongju Hospital, Gyeongju, Republic of Korea.
authors.forename: Kyung Don
authors.initials: KD
authors.lastname: Yoo
authors.affiliation: Seoul National University Hospital, Medical Research Collaborating Center, Seoul, Republic of Korea.
authors.forename: Yunhee
authors.initials: Y
authors.lastname: Choi
authors.affiliation: Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea.
authors.forename: Dong Ki
authors.initials: DK
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea.
authors.forename: Kwon Wook
authors.initials: KW
authors.lastname: Joo
authors.affiliation: Seoul National University Kidney Research Institute, Seoul, Republic of Korea.
authors.forename: Seung Hee
authors.initials: SH
authors.lastname: Yang
authors.affiliation: Department of Internal Medicine, Kyungpook National University Hospital, Daegu, Republic of Korea.
authors.forename: Yong-Lim
authors.initials: YL
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Shin-Wook
authors.initials: SW
authors.lastname: Kang
authors.affiliation: Department of Internal Medicine, Seoul St. Mary's Hospital, Seoul, Republic of Korea.
authors.forename: Chul Woo
authors.initials: CW
authors.lastname: Yang
authors.affiliation: Department of Internal Medicine, Chonnam National University Hospital, Gwangju, Republic of Korea.
authors.forename: Nam Ho
authors.initials: NH
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea.
authors.forename: Yon Su
authors.initials: YS
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Seoul National University Hospital, Seoul, Republic of Korea.|Seoul National University Kidney Research Institute, Seoul, Republic of Korea.
authors.forename: Hajeong
authors.initials: H
authors.lastname: Lee
mesh_terms: D002423:Cause of Death; D005260:Female; D006801:Humans; D015994:Incidence; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000453:epidemiology / Q000401:mortality* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D011188:Potassium / Q000097:blood*; D016016:Proportional Hazards Models; D011446:Prospective Studies; D006435:Renal Dialysis / Q000401:mortality*; D056910:Republic of Korea / Q000453:epidemiology
chemical_list: D011188:Potassium