title: Serum potassium and cause-specific mortality in a large peritoneal dialysis cohort.
abstract: OBJECTIVE
  Unlike hemodialysis (HD), peritoneal dialysis (PD) is a continuous therapy and does not induce myocardial stunning. Yet, the death risk in HD and PD patients is similar. This study tested the hypothesis that serum potassium abnormalities contribute more to the death risk in PD patients than in HD patients.
  
  
  METHODS
  Data from patients treated in DaVita facilities between July 1, 2001 and June 30, 2006 (n=10,468 PD patients; n=111,651 HD patients) were used to determine association of serum potassium with mortality.
  
  
  RESULTS
  PD patients were significantly more likely to have serum potassium < 4 mEq/L, with an adjusted odds ratio of 3.30 (95% confidence interval [95% CI], 3.05, 3.56). There was a U-shaped relationship between time-averaged serum potassium and all-cause and cardiovascular mortality of PD patients, with adjusted hazards ratios of 1.51 for all-cause mortality for potassium < 3.5 mEq/L (95% CI, 1.29, 1.76) and 1.52 for potassium ≥ 5.5 mEq/L (95% CI, 1.32, 1.75). The population-attributable risks for all-cause mortality for serum potassium < 4.0 and ≥ 5.5 mEq/L were 3.6% and 1.9%, respectively, in PD patients, and 0.8% and 1.5%, respectively, in HD patients.
  
  
  CONCLUSIONS
  Abnormalities in serum potassium contribute disproportionately to the high death risk in PD patients. This may, in part, account for the equivalent cardiac risk seen with the two therapies.
authors.affiliation: Karolinska Institute, Stockholm, Sweden.
authors.forename: Klara
authors.initials: K
authors.lastname: Torlén
authors.forename: Kamyar
authors.initials: K
authors.lastname: Kalantar-Zadeh
authors.forename: Miklos Z
authors.initials: MZ
authors.lastname: Molnar
authors.forename: Tania
authors.initials: T
authors.lastname: Vashistha
authors.forename: Rajnish
authors.initials: R
authors.lastname: Mehrotra
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D002318:Cardiovascular Diseases / Q000097:blood / Q000209:etiology / Q000401:mortality*; D002423:Cause of Death; D015536:Down-Regulation; D005260:Female; D006801:Humans; D007008:Hypokalemia / Q000097:blood / Q000209:etiology / Q000401:mortality*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D010530:Peritoneal Dialysis / Q000009:adverse effects / Q000401:mortality*; D011188:Potassium / Q000097:blood*; D016016:Proportional Hazards Models; D006435:Renal Dialysis / Q000009:adverse effects / Q000401:mortality*; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D014481:United States
chemical_list: D015415:Biomarkers; D011188:Potassium