title: Serum sodium and mortality in a national peritoneal dialysis cohort.
abstract: BACKGROUND
  Sodium disarrays are common in peritoneal dialysis (PD) patients, and may be associated with adverse outcomes in this population. However, few studies of limited sample size have examined the association of serum sodium with mortality in PD patients, with inconsistent results. We hypothesized that both hypo- and hypernatremia are associated with higher death risk in a nationally representative cohort of US PD patients.
  
  
  METHODS
  We sought to examine the association of serum sodium over time and mortality among 4687 adult incident PD patients from a large US dialysis organization who underwent one or more serum sodium measurements within the first 3 months of dialysis over January 2007 to December 2011. We examined the association of time-dependent and baseline sodium with all-cause mortality as a proxy of short- and long-term sodium-mortality associations, respectively. Hazard ratios were estimated using Cox models with three adjustment levels: minimally adjusted, case-mix adjusted, and case-mix + laboratory adjusted.
  
  
  RESULTS
  In time-dependent analyses, sodium levels <140 mEq/L were associated with incrementally higher death risk in case-mix models (ref: 140 to <142 mEq/L); following laboratory covariate adjustment, associations between lower sodium and higher mortality remained significant for levels <136 mEq/L. In analyses using baseline values, sodium levels <140 mEq/L were associated with higher mortality risk across all models (ref: 140 to <142 mEq/L).
  
  
  CONCLUSIONS
  In PD patients, lower time-dependent and baseline sodium levels were independently associated with higher death risk. Further studies are needed to determine whether correction of dysnatremia improves longevity in this population.
authors.affiliation: Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine Medical Center, Orange, CA, USA.
authors.forename: Vanessa A
authors.initials: VA
authors.lastname: Ravel
authors.affiliation: Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine Medical Center, Orange, CA, USA.
authors.forename: Elani
authors.initials: E
authors.lastname: Streja
authors.affiliation: Kidney Research Institute and Harborview Medical Center, University of Washington, Seattle, WA, USA.
authors.forename: Rajnish
authors.initials: R
authors.lastname: Mehrotra
authors.affiliation: Division of Nephrology, Kaiser Permanente Southern California, Los Angeles, CA, USA.
authors.forename: John J
authors.initials: JJ
authors.lastname: Sim
authors.affiliation: Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine Medical Center, Orange, CA, USA.
authors.forename: Kevin
authors.initials: K
authors.lastname: Harley
authors.affiliation: Renal Consultants of Houston, Houston, TX, USA.
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Ayus
authors.affiliation: Department of Medicine, University of California Irvine Medical Center, Orange, CA, USA.
authors.forename: Alpesh N
authors.initials: AN
authors.lastname: Amin
authors.affiliation: DaVita Clinical Research, Minneapolis, MN, USA.
authors.forename: Steven M
authors.initials: SM
authors.lastname: Brunelli
authors.affiliation: University of Tennessee Health Science Center, Memphis, TN, USA.|Memphis Veterans Affairs Medical Center, Memphis, TN, USA.
authors.forename: Csaba P
authors.initials: CP
authors.lastname: Kovesdy
authors.affiliation: Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine Medical Center, Orange, CA, USA.
authors.forename: Kamyar
authors.initials: K
authors.lastname: Kalantar-Zadeh
authors.affiliation: Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine Medical Center, Orange, CA, USA.
authors.forename: Connie M
authors.initials: CM
authors.lastname: Rhee
mesh_terms: D015415:Biomarkers / Q000097:blood*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D006955:Hypernatremia / Q000097:blood / Q000209:etiology / Q000401:mortality*; D007010:Hyponatremia / Q000097:blood / Q000209:etiology / Q000401:mortality*; D008297:Male; D008875:Middle Aged; D009026:Mortality / Q000639:trends*; D010530:Peritoneal Dialysis / Q000009:adverse effects / Q000401:mortality*; D011379:Prognosis; D012964:Sodium / Q000097:blood*; D015996:Survival Rate
chemical_list: D015415:Biomarkers; D012964:Sodium
keywords: hypernatremia; hyponatremia; mortality; peritoneal dialysis; sodium