title: Urinary sodium and potassium excretion and risk of cardiovascular events.
abstract: BACKGROUND
  The precise relationship between sodium and potassium intake and cardiovascular (CV) risk remains uncertain, especially in patients with CV disease.
  
  
  OBJECTIVE
  To determine the association between estimated urinary sodium and potassium excretion (surrogates for intake) and CV events in patients with established CV disease or diabetes mellitus.
  
  
  METHODS
  Observational analyses of 2 cohorts (N = 28,880) included in the ONTARGET and TRANSCEND trials (November 2001-March 2008 from initial recruitment to final follow-up). We estimated 24-hour urinary sodium and potassium excretion from a morning fasting urine sample (Kawasaki formula). We used restricted cubic spline plots to describe the association between sodium and potassium excretion and CV events and mortality, and to identify reference categories for sodium and potassium excretion. We used Cox proportional hazards multivariable models to determine the association of urinary sodium and potassium with CV events and mortality.
  
  
  METHODS
  CV death, myocardial infarction (MI), stroke, and hospitalization for congestive heart failure (CHF).
  
  
  RESULTS
  At baseline, the mean (SD) estimated 24-hour excretion for sodium was 4.77 g (1.61); and for potassium was 2.19 g (0.57). After a median follow-up of 56 months, the composite outcome occurred in 4729 (16.4%) participants, including 2057 CV deaths, 1412 with MI, 1282 with stroke, and 1213 with hospitalization for CHF. Compared with the reference group with estimated baseline sodium excretion of 4 to 5.99 g per day (n = 14,156; 6.3% participants with CV death, 4.6% with MI, 4.2% with stroke, and 3.8% admitted to hospital with CHF), higher baseline sodium excretion was associated with an increased risk of CV death (9.7% for 7-8 g/day; hazard ratio [HR], 1.53; 95% CI, 1.26-1.86; and 11.2% for >8 g/day; HR, 1.66; 95% CI, 1.31-2.10), MI (6.8%; HR, 1.48; 95% CI, 1.11-1.98 for >8 g/day), stroke (6.6%; HR, 1.48; 95% CI, 1.09-2.01 for >8 g/day), and hospitalization for CHF (6.5%; HR, 1.51; 1.12-2.05 for >8 g/day). Lower sodium excretion was associated with an increased risk of CV death (8.6%; HR, 1.19; 95% CI, 1.02-1.39 for 2-2.99 g/day; 10.6%; HR, 1.37; 95% CI, 1.09-1.73 for <2 g/day), and hospitalization for CHF (5.2%; HR, 1.23; 95% CI, 1.01-1.49 for 2-2.99 g/day) on multivariable analysis. Compared with an estimated potassium excretion of less than 1.5 g per day (n = 2194; 6.2% with stroke), higher potassium excretion was associated with a reduced risk of stroke (4.7% [HR, 0.77; 95% CI, 0.63-0.94] for 1.5-1.99 g/day; 4.3% [HR, 0.73; 95% CI, 0.59-0.90] for 2-2.49 g/day; 3.9% [HR, 0.71; 95% CI, 0.56-0.91] for 2.5-3 g/day; and 3.5% [HR, 0.68; 95% CI, 0.49-0.92] for >3 g/day) on multivariable analysis.
  
  
  CONCLUSIONS
  The association between estimated sodium excretion and CV events was J-shaped. Compared with baseline sodium excretion of 4 to 5.99 g per day, sodium excretion of greater than 7 g per day was associated with an increased risk of all CV events, and a sodium excretion of less than 3 g per day was associated with increased risk of CV mortality and hospitalization for CHF. Higher estimated potassium excretion was associated with a reduced risk of stroke.
authors: Population Health Research Institute, Hamilton General Hospital, McMaster University, 237 Barton St E, Third Floor, Hamilton, ON, L8L 2X2, Canada. odonnm@mcmaster.ca
authors: Martin J
authors: MJ
authors: O'Donnell
authors: Salim
authors: S
authors: Yusuf
authors: Andrew
authors: A
authors: Mente
authors: Peggy
authors: P
authors: Gao
authors: Johannes F
authors: JF
authors: Mann
authors: Koon
authors: K
authors: Teo
authors: Matthew
authors: M
authors: McQueen
authors: Peter
authors: P
authors: Sleight
authors: Arya M
authors: AM
authors: Sharma
authors: Antonio
authors: A
authors: Dans
authors: Jeffrey
authors: J
authors: Probstfield
authors: Roland E
authors: RE
authors: Schmieder
mesh_terms: D000368:Aged; D015331:Cohort Studies; D003920:Diabetes Mellitus; D005260:Female; D006333:Heart Failure / Q000401:mortality* / Q000652:urine; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000401:mortality* / Q000652:urine; D011188:Potassium / Q000652:urine*; D016032:Randomized Controlled Trials as Topic; D012306:Risk; D012964:Sodium / Q000652:urine*; D012982:Sodium, Dietary / Q000009:adverse effects*; D020521:Stroke / Q000453:epidemiology / Q000517:prevention & control; D016482:Urinalysis
chemical_list: D012982:Sodium, Dietary; D012964:Sodium; D011188:Potassium