Kidney Week

Abstract: FR-PO1153

Longitudinal Measures of Serum Bicarbonate and Kidney Disease Progression: Results from the CKiD Cohort

Session Information

• Pediatric Nephrology - I
  October 26, 2018 | Location: Exhibit Hall, San Diego Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Pediatric Nephrology

• 1600 Pediatric Nephrology

Authors

• Brown, Denver D., The Childrens Hospital at Montefiore, Bronx, New York, United States

Denver D. Brown,

• Reidy, Kimberly J., Children's Hospital at Montefiore/ Albert Einstein College of Medicine, Bronxville, New York, United States

Kimberly J. Reidy,

• Roem, Jennifer, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States

Jennifer Roem,

• Ng, Derek, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States

Derek Ng,

• Kumar, Juhi, Weill Cornell Medical College, New York, New York, United States

Juhi Kumar,

• Abramowitz, Matthew K., Albert Einstein College of Medicine, Bronx, New York, United States

Matthew K. Abramowitz,

• Furth, Susan L., The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States

Susan L. Furth,

• Schwartz, George J., University of Rochester, Rochester, New York, United States

George J. Schwartz,

• Warady, Bradley A., Children's Mercy Kansas City , Kansas City, Missouri, United States

Bradley A. Warady,

• Kaskel, Frederick J., Children’s Hospital at Montefiore, Bronx, New York, United States

Frederick J. Kaskel,

• Melamed, Michal L., Albert Einstein College of Medicine, Bronx, New York, United States

Michal L. Melamed,

Background

Acidosis is a frequent complication of pediatric CKD; however, the longitudinal changes of serum bicarbonate over time in glomerular and non-glomerular kidney disease has not been examined.

Methods

This study consisted of 787 children with at least two serum bicarbonate measurements in the CKiD cohort. To describe baseline bicarbonate levels and changes over time, linear mixed models with random intercepts were fit with bicarbonate in the log scale. The relationship between bicarbonate and eGFR was described using a repeated measures linear regression with generalized estimating equations. All analyses were stratified by underlying non-glomerular and glomerular diagnoses.

Results

558 children with non-glomerular CKD contributed 3325 visits, and 229 with a glomerular diagnosis contributed 1050 visits. The prevalence of acidosis (serum bicarbonate <22 mmol/L) at baseline was 38% and 28% for those with a non-glomerular and glomerular diagnosis, respectively (p= 0.01). The prevalence of alkali therapy at baseline was 30% and 8%, respectively. For those with non-glomerular disease, the mean baseline bicarbonate level was 23.1 mmol/L (95%CI: 22.9, 23.3) and the mean change per year was +0.1% (95%CI: -0.1%, +0.3%). Among those with glomerular disease, the mean baseline bicarbonate level was 24.0 mmol/L (95%CI: 23.6, 24.4) and the mean change per year was -0.4% (95%CI: -0.7%, -0.003%), indicating a significant reduction over time. Per 20% decrease in eGFR, those with non-glomerular CKD had a decrease of -2.39% (-2.79% to -1.99%) while children with glomerular disease had a -3.23% decrease (-3.72% to -2.74%) in their bicarbonate levels (p=0.01 for the comparison). Baseline acidosis was associated with a faster decline in eGFR (-6.0% [-12.8% to -1.0%] vs. -2.9% [-6.8% to -0.4%], p<0.001) in non-glomerular CKD but not in glomerular CKD (-4.8% [-14.9% to 0.3%] vs. -6.0% [-14.0% to -1.4%]).

Conclusion

In non-glomerular CKD, bicarbonate levels start lower but do not decrease as rapidly as in children with glomerular CKD. However, low baseline bicarbonate levels are associated with a faster decline in eGFR only in those children with non-glomerular CKD. Future data will assess whether these relationships may be attenuated by effective alkali therapy.