title: Hypokalemia and outcomes in patients with chronic heart failure and chronic kidney disease: findings from propensity-matched studies.
abstract: BACKGROUND
  Little is known about the effects of hypokalemia on outcomes in patients with chronic heart failure (HF) and chronic kidney disease.
  
  
  RESULTS
  Of the 7788 patients with chronic HF in the Digitalis Investigation Group trial, 2793 had chronic kidney disease, defined as estimated glomerular filtration rate <60 mL/min per 1.73 m(2). Of these, 527 had hypokalemia (serum potassium <4 mEq/L; mild) and 2266 had normokalemia (4 to 4.9 mEq/L). Propensity scores for hypokalemia were used to assemble a balanced cohort of 522 pairs of patients with hypokalemia and normokalemia. All-cause mortality occurred in 48% and 36% of patients with hypokalemia and normokalemia, respectively, during 57 months of follow-up (matched hazard ratio when hypokalemia was compared with normokalemia, 1.56; 95% CI, 1.25 to 1.95; P<0.0001). Matched hazard ratios (95% CIs) for cardiovascular and HF mortalities and all-cause, cardiovascular, and HF hospitalizations were 1.65 (1.29 to 2.11; P<0.0001), 1.82 (1.28 to 2.57; P<0.0001), 1.16 (1.00 to 1.35; P=0.036), 1.27 (1.08 to 1.50; P=0.004), and 1.29 (1.05 to 1.58; P=0.014), respectively. Among 453 pairs of balanced patients with HF and chronic kidney disease, all-cause mortality occurred in 47% and 38% of patients with mild hypokalemia (3.5 to 3.9 mEq/L) and normokalemia, respectively (matched hazard ratio, 1.31; 95% CI, 1.03 to 1.66; P=0.027). Among 169 pairs of balanced patients with estimated glomerular filtration rate <45 mL/min per 1.73 m(2), all-cause mortality occurred in 57% and 47% of patients with hypokalemia (<4 mEq/L; mild) and normokalemia, respectively (matched hazard ratio, 1.53; 95% CI, 1.07 to 2.19; P=0.020).
  
  
  CONCLUSIONS
  In patients with HF and chronic kidney disease, hypokalemia (serum potassium <4 mEq/L) is common and associated with increased mortality and hospitalization.
authors.affiliation: Section of Geriatrics, VA Medical Center, Birmingham, Ala, USA.
authors.forename: C Barrett
authors.initials: CB
authors.lastname: Bowling
authors.forename: Bertram
authors.initials: B
authors.lastname: Pitt
authors.forename: Mustafa I
authors.initials: MI
authors.lastname: Ahmed
authors.forename: Inmaculada B
authors.initials: IB
authors.lastname: Aban
authors.forename: Paul W
authors.initials: PW
authors.lastname: Sanders
authors.forename: Marjan
authors.initials: M
authors.lastname: Mujib
authors.forename: Ruth C
authors.initials: RC
authors.lastname: Campbell
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Love
authors.forename: Wilbert S
authors.initials: WS
authors.lastname: Aronow
authors.forename: Richard M
authors.initials: RM
authors.lastname: Allman
authors.forename: George L
authors.initials: GL
authors.lastname: Bakris
authors.forename: Ali
authors.initials: A
authors.lastname: Ahmed
mesh_terms: D000368:Aged; D002170:Canada / Q000453:epidemiology; D002423:Cause of Death; D016009:Chi-Square Distribution; D002908:Chronic Disease; D005260:Female; D005919:Glomerular Filtration Rate; D006333:Heart Failure / Q000097:blood* / Q000150:complications* / Q000401:mortality; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D007008:Hypokalemia / Q000209:etiology* / Q000401:mortality; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000150:complications* / Q000401:mortality; D008297:Male; D016016:Proportional Hazards Models; D018709:Statistics, Nonparametric; D014481:United States / Q000453:epidemiology