Pre-dialysis serum sodium and mortality in a national incident hemodialysis cohort

Connie M. Rhee, Vanessa A. Ravel, Juan Carlos Ayus, John J. Sim, Elani Streja, Rajnish Mehrotra, Alpesh N. Amin, Danh V. Nguyen, Steven M. Brunelli, Csaba Kovesdy, Kamyar Kalantar-Zadeh

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Abstract

Background A consistent association between low serum sodium measured at a single-point-in-time (baseline sodium) and higher mortality has been observed in hemodialysis patients. We hypothesized that both low and high time-varying sodium levels (sodium levels updated at quarterly intervals as a proxy of short-term exposure) are independently associated with higher death risk in hemodialysis patients. MethodsWe examined the association of baseline and time-varying pre-dialysis serum sodium levels with all-cause mortality among adult incident hemodialysis patients receiving care from a large national dialysis organization during January 2007-December 2011. Hazard ratios were estimated using multivariable Cox models accounting for case-mix+laboratory covariates and incrementally adjusted for inter-dialytic weight gain, blood urea nitrogen and glucose. ResultsAmong 27 180 patients, a total of 7562 deaths were observed during 46 194 patient-years of follow-up. Median (IQR) at-risk time was 1.4 (0.6, 2.5) years. In baseline analyses adjusted for case-mix+laboratory results, sodium levels <138 mEq/L were associated with incrementally higher mortality risk, while the association of sodium levels ≥140 mEq/L with lower mortality reached statistical significance only for the highest level of pre-dialysis sodium (reference: 138-<140 mEq/L). In time-varying analyses, we observed a U-shaped association between sodium and mortality such that sodium levels <138 and ≥144 mEq/L were associated with higher mortality risk. Similar patterns were observed in models incrementally adjusted for inter-dialytic weight gain, blood urea nitrogen and glucose. ConclusionsWe observed a U-shaped association of time-varying pre-dialysis serum sodium and all-cause mortality in hemodialysis patients, suggesting that both hypo- and hypernatremia carry short-term risk in this population.

Original languageEnglish (US)
Pages (from-to)992-1001
Number of pages10
JournalNephrology Dialysis Transplantation
Volume31
Issue number6
DOIs
StatePublished - Jun 24 2016

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Renal Dialysis
Dialysis
Sodium
Mortality
Serum
Diagnosis-Related Groups
Blood Urea Nitrogen
Weight Gain
Hypernatremia
Glucose
Hyponatremia
Proxy
Proportional Hazards Models
Patient Care

All Science Journal Classification (ASJC) codes

  • Nephrology
  • Transplantation

Cite this

Rhee, C. M., Ravel, V. A., Ayus, J. C., Sim, J. J., Streja, E., Mehrotra, R., ... Kalantar-Zadeh, K. (2016). Pre-dialysis serum sodium and mortality in a national incident hemodialysis cohort. Nephrology Dialysis Transplantation, 31(6), 992-1001. https://doi.org/10.1093/ndt/gfv341

Pre-dialysis serum sodium and mortality in a national incident hemodialysis cohort. / Rhee, Connie M.; Ravel, Vanessa A.; Ayus, Juan Carlos; Sim, John J.; Streja, Elani; Mehrotra, Rajnish; Amin, Alpesh N.; Nguyen, Danh V.; Brunelli, Steven M.; Kovesdy, Csaba; Kalantar-Zadeh, Kamyar.

In: Nephrology Dialysis Transplantation, Vol. 31, No. 6, 24.06.2016, p. 992-1001.

Research output: Contribution to journalArticle

Rhee, CM, Ravel, VA, Ayus, JC, Sim, JJ, Streja, E, Mehrotra, R, Amin, AN, Nguyen, DV, Brunelli, SM, Kovesdy, C & Kalantar-Zadeh, K 2016, 'Pre-dialysis serum sodium and mortality in a national incident hemodialysis cohort', Nephrology Dialysis Transplantation, vol. 31, no. 6, pp. 992-1001. https://doi.org/10.1093/ndt/gfv341
Rhee, Connie M. ; Ravel, Vanessa A. ; Ayus, Juan Carlos ; Sim, John J. ; Streja, Elani ; Mehrotra, Rajnish ; Amin, Alpesh N. ; Nguyen, Danh V. ; Brunelli, Steven M. ; Kovesdy, Csaba ; Kalantar-Zadeh, Kamyar. / Pre-dialysis serum sodium and mortality in a national incident hemodialysis cohort. In: Nephrology Dialysis Transplantation. 2016 ; Vol. 31, No. 6. pp. 992-1001.
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abstract = "Background A consistent association between low serum sodium measured at a single-point-in-time (baseline sodium) and higher mortality has been observed in hemodialysis patients. We hypothesized that both low and high time-varying sodium levels (sodium levels updated at quarterly intervals as a proxy of short-term exposure) are independently associated with higher death risk in hemodialysis patients. MethodsWe examined the association of baseline and time-varying pre-dialysis serum sodium levels with all-cause mortality among adult incident hemodialysis patients receiving care from a large national dialysis organization during January 2007-December 2011. Hazard ratios were estimated using multivariable Cox models accounting for case-mix+laboratory covariates and incrementally adjusted for inter-dialytic weight gain, blood urea nitrogen and glucose. ResultsAmong 27 180 patients, a total of 7562 deaths were observed during 46 194 patient-years of follow-up. Median (IQR) at-risk time was 1.4 (0.6, 2.5) years. In baseline analyses adjusted for case-mix+laboratory results, sodium levels <138 mEq/L were associated with incrementally higher mortality risk, while the association of sodium levels ≥140 mEq/L with lower mortality reached statistical significance only for the highest level of pre-dialysis sodium (reference: 138-<140 mEq/L). In time-varying analyses, we observed a U-shaped association between sodium and mortality such that sodium levels <138 and ≥144 mEq/L were associated with higher mortality risk. Similar patterns were observed in models incrementally adjusted for inter-dialytic weight gain, blood urea nitrogen and glucose. ConclusionsWe observed a U-shaped association of time-varying pre-dialysis serum sodium and all-cause mortality in hemodialysis patients, suggesting that both hypo- and hypernatremia carry short-term risk in this population.",
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AU - Rhee, Connie M.

AU - Ravel, Vanessa A.

AU - Ayus, Juan Carlos

AU - Sim, John J.

AU - Streja, Elani

AU - Mehrotra, Rajnish

AU - Amin, Alpesh N.

AU - Nguyen, Danh V.

AU - Brunelli, Steven M.

AU - Kovesdy, Csaba

AU - Kalantar-Zadeh, Kamyar

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Y1 - 2016/6/24

N2 - Background A consistent association between low serum sodium measured at a single-point-in-time (baseline sodium) and higher mortality has been observed in hemodialysis patients. We hypothesized that both low and high time-varying sodium levels (sodium levels updated at quarterly intervals as a proxy of short-term exposure) are independently associated with higher death risk in hemodialysis patients. MethodsWe examined the association of baseline and time-varying pre-dialysis serum sodium levels with all-cause mortality among adult incident hemodialysis patients receiving care from a large national dialysis organization during January 2007-December 2011. Hazard ratios were estimated using multivariable Cox models accounting for case-mix+laboratory covariates and incrementally adjusted for inter-dialytic weight gain, blood urea nitrogen and glucose. ResultsAmong 27 180 patients, a total of 7562 deaths were observed during 46 194 patient-years of follow-up. Median (IQR) at-risk time was 1.4 (0.6, 2.5) years. In baseline analyses adjusted for case-mix+laboratory results, sodium levels <138 mEq/L were associated with incrementally higher mortality risk, while the association of sodium levels ≥140 mEq/L with lower mortality reached statistical significance only for the highest level of pre-dialysis sodium (reference: 138-<140 mEq/L). In time-varying analyses, we observed a U-shaped association between sodium and mortality such that sodium levels <138 and ≥144 mEq/L were associated with higher mortality risk. Similar patterns were observed in models incrementally adjusted for inter-dialytic weight gain, blood urea nitrogen and glucose. ConclusionsWe observed a U-shaped association of time-varying pre-dialysis serum sodium and all-cause mortality in hemodialysis patients, suggesting that both hypo- and hypernatremia carry short-term risk in this population.

AB - Background A consistent association between low serum sodium measured at a single-point-in-time (baseline sodium) and higher mortality has been observed in hemodialysis patients. We hypothesized that both low and high time-varying sodium levels (sodium levels updated at quarterly intervals as a proxy of short-term exposure) are independently associated with higher death risk in hemodialysis patients. MethodsWe examined the association of baseline and time-varying pre-dialysis serum sodium levels with all-cause mortality among adult incident hemodialysis patients receiving care from a large national dialysis organization during January 2007-December 2011. Hazard ratios were estimated using multivariable Cox models accounting for case-mix+laboratory covariates and incrementally adjusted for inter-dialytic weight gain, blood urea nitrogen and glucose. ResultsAmong 27 180 patients, a total of 7562 deaths were observed during 46 194 patient-years of follow-up. Median (IQR) at-risk time was 1.4 (0.6, 2.5) years. In baseline analyses adjusted for case-mix+laboratory results, sodium levels <138 mEq/L were associated with incrementally higher mortality risk, while the association of sodium levels ≥140 mEq/L with lower mortality reached statistical significance only for the highest level of pre-dialysis sodium (reference: 138-<140 mEq/L). In time-varying analyses, we observed a U-shaped association between sodium and mortality such that sodium levels <138 and ≥144 mEq/L were associated with higher mortality risk. Similar patterns were observed in models incrementally adjusted for inter-dialytic weight gain, blood urea nitrogen and glucose. ConclusionsWe observed a U-shaped association of time-varying pre-dialysis serum sodium and all-cause mortality in hemodialysis patients, suggesting that both hypo- and hypernatremia carry short-term risk in this population.

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