title: Serum Potassium Levels and Mortality in Hemodialysis Patients: A Retrospective Cohort Study.
abstract: Hyperkalemia is common in patients receiving maintenance hemodialysis. However, few studies have examined the association between serum potassium level and mortality.
  
  
  
  This study used annual cohorts of hemodialysis patients during 2007-2010. To determine hyperkalemia prevalence, monthly hyperkalemia was defined as serum potassium level ≥5.5 mEq/l; prevalence was calculated as a ratio of hyperkalemia episodes to follow-up time, reported separately by long and short interdialytic interval. To determine the impact of hyperkalemia on mortality, patients in the 2010 cohort were followed from first potassium measurement until death or a censoring event; hyperkalemia was defined, sequentially, by potassium levels 5.5-6.0 mEq/l at 0.1 mEq/l intervals. Time-dependent Cox proportional hazards modeling was used to estimate the association between hyperkalemia and mortality.
  
  
  
  The 4 annual cohorts ranged from 28,774 to 36,888 patients. Mean age was approximately 63 years, about 56% were men, 51% were white and 44% had end-stage renal disease caused by diabetes. Hyperkalemia prevalence was consistently estimated at 16.3-16.8 events per 100 patient-months. Prevalence on the day after the long interdialytic interval was 2.0-2.4 times as high as on the day after the short interval. Hyperkalemia, when defined as serum potassium ≥5.7 mEq/l, was associated with all-cause mortality (adjusted hazards ratio (AHR) 1.13, 95% CI 1.01-1.28, p = 0.037, vs. <5.7 mEq/l) after adjustment. AHRs increased progressively as the hyperkalemia threshold increased, reaching 1.37 (95% CI 1.16-1.62, p < 0.0001) for ≥6.0 mEq/l.
  
  
  
  The long interdialytic interval was associated with increased likelihood of hyperkalemia. Hyperkalemia was associated with all-cause mortality beginning at serum potassium ≥5.7 mEq/l; mortality risk estimates increased ordinally through ≥6.0 mEq/l, suggesting a threshold at which serum potassium becomes substantially more dangerous.
authors: Chronic Disease Research Group, Minneapolis Medical Research Foundation, Minneapolis, Minn., USA.
authors: Akeem A
authors: AA
authors: Yusuf
authors: Yan
authors: Y
authors: Hu
authors: Bhupinder
authors: B
authors: Singh
authors: José A
authors: JA
authors: Menoyo
authors: James B
authors: JB
authors: Wetmore
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002423:Cause of Death; D005260:Female; D006801:Humans; D006947:Hyperkalemia / Q000453:epidemiology / Q000401:mortality*; D007676:Kidney Failure, Chronic / Q000628:therapy; D008297:Male; D008875:Middle Aged; D011188:Potassium / Q000097:blood*; D015995:Prevalence; D016016:Proportional Hazards Models; D006435:Renal Dialysis / Q000379:methods; D012189:Retrospective Studies; D013997:Time Factors; D014481:United States / Q000453:epidemiology; D055815:Young Adult
chemical_list: D011188:Potassium