NDT Advance Access originally published online on November 17, 2008
Nephrology Dialysis Transplantation 2009 24(4):1232-1237; doi:10.1093/ndt/gfn633
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Published by Oxford University Press on behalf of ERA-EDTA [2008].
Association of serum bicarbonate levels with mortality in patients with non-dialysis-dependent CKD
1 Division of Nephrology, Salem Veterans Affairs Medical Center, Salem 2 Department of Medicine, University of Virginia, Charlottesville, VA 3 Division of Nephrology, Johns Hopkins Bayview Medical Center, Baltimore, MD 4 Harold Simmons Center for Kidney Disease Research and Epidemiology, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance 5 David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
Correspondence and offprint requests to: Csaba P. Kovesdy, Division of Nephrology, Salem Veterans Affairs Medical Center, 1970 Roanoke Blvd., Salem, VA 24153, USA. Tel: +1-540-982-2463; Fax: +1-540-224-1963; E-mail: csaba.kovesdy{at}va.gov
| Abstract |
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Background. Metabolic acidosis, usually manifested by low serum bicarbonate level, is common in chronic kidney disease (CKD) and appears to be associated with higher mortality in dialysis patients. It is not known whether a similar association is present in patients with non-dialysis-dependent CKD (NDD-CKD).
Methods. We used multivariable-adjusted Cox models to examine the association between baseline and time-variable serum bicarbonate (measured as total CO2) with the outcomes of all-cause mortality and the composite of pre-dialysis mortality or end-stage renal disease in 1240 male patients with moderate and advanced NDD-CKD.
Results. Serum bicarbonate showed a significant U-shaped association with all-cause mortality, with the highest mortality rate observed in patients with baseline serum bicarbonate levels <22 mmol/L [multivariable-adjusted hazard ratio (95% confidence interval) for patients with serum bicarbonate <22 mmol/L versus
22 mmol/L: 1.33 (1.05–1.69), P = 0.02] and the lowest mortality observed in patients with baseline serum bicarbonate of 26–29 mmol/L. The associations between lower serum bicarbonate level and mortality were more accentuated in subgroups of patients with better nutritional status and lower inflammation.
Conclusions. Both lower and higher serum bicarbonates are associated with increased all-cause mortality in patients with moderate and advanced NDD-CKD. Clinical trials are needed to determine if therapeutic interventions aimed at optimizing serum bicarbonate can result in improved outcomes in this population.
Keywords: bicarbonate; chronic kidney disease; mortality
Received for publication: 4. 9.08
Accepted in revised form: 20.10.08