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Clin J Am Soc Nephrol. 2011 Oct;6(10):2395-402. doi: 10.2215/CJN.03730411. Epub 2011 Sep 1.

Serum bicarbonate and mortality in stage 3 and stage 4 chronic kidney disease.

Author information

1
Department of Nephrology, Hypertension, Glickman Urological and Kidney Institute, and Cleveland Clinic Lerner College of Medicine of CWRU, Cleveland, OH 44195, USA. navanes@ccf.org

Abstract

BACKGROUND AND OBJECTIVES:

The incidence and prevalence of metabolic acidosis increase with declining kidney function. We studied the associations of both low and high serum bicarbonate levels with all-cause mortality among stage 3 and 4 chronic kidney disease (CKD) patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS:

We examined factors associated with low (<23 mmol/L) and high (>32 mmol/L) serum bicarbonate levels using logistic regression models and associations between bicarbonate and all-cause mortality using Cox-proportional hazard models, Kaplan-Meier survival curves, and time-dependent analysis.

RESULTS:

Out of 41,749 patients, 13.9% (n = 5796) had low and 1.6% (n = 652) had high serum bicarbonate levels. After adjusting for relevant covariates, there was a significant association between low serum bicarbonate and all-cause mortality (hazard ratio [HR] 1.23, 95% CI 1.16, 1.31). This association was not statistically significant among patients with stage 4 CKD and diabetes. The time-dependent analysis demonstrated a significant mortality risk associated with a decline from normal to low bicarbonate level (HR 1.59, 95% CI 1.49, 1.69). High serum bicarbonate levels were associated with death irrespective of the level of kidney function (HR 1.74, 95% CI 1.52, 2.00). When serum bicarbonate was examined as a continuous variable, a J-shaped relationship was noted between serum bicarbonate and mortality.

CONCLUSIONS:

Low serum bicarbonate levels are associated with increased mortality among stage 3 CKD patients and patients without diabetes. High serum bicarbonate levels are associated with mortality in both stage 3 and stage 4 CKD patients.

PMID:
21885787
PMCID:
PMC3359558
DOI:
10.2215/CJN.03730411
[Indexed for MEDLINE]
Free PMC Article

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