Metabolic Acidosis Associated with Poor Outcomes in CKD

Patients with advanced chronic kidney disease (CKD) commonly experience metabolic acidosis, a complication that is associated with adverse outcomes. Nancy Reaven, MA, and colleagues conducted an analysis designed to examine the association between metabolic acidosis and death and other major adverse kidney outcomes in a large US community-based population. Results were reported during the National Kidney Foundation Spring Clinical Meetings 2019 in a presentation titled Adverse Clinical Outcomes in Patients with chronic Kidney Disease and Metabolic Acidosis: A Longitudinal Analysis from Electronic Medical Records of >50,000 Patients.

The longitudinal analysis utilized data from electronic medical records (Optum®) from 2007 to 2017 to identify non-dialysis CKD patients with two or more serum bicarbonate (HCO3) tests 28 to 365 days apart, three or more estimated glomerular filtration rate (eGFR) values <60 mL/min/1.73 m², and two or more years of post-index data or death. Patients were followed for 2 years.

The composite outcome of interest was death, chronic dialysis, kidney transplant, or decline in eGFR ≥40% (other than during a diagnosis of acute kidney injury). The impact of baseline HCO3 (continuous) or metabolic acidosis (yes/no) on the composite outcome was evaluated using Cox proportional hazards models following adjustment for age, sex, diabetes, hypertension, and eGFR; interactions were also accounted for.

The analyses included 51,558 patients. Of those, 10,725 were <65 years of age, 48% had metabolic acidosis at baseline; 40,833 were >65 years of age and 30% had metabolic acidosis at baseline. At 2 years, the composite events occurred at a 2- to 3-fold higher frequency in patients with metabolic acidosis compared with patients without metabolic acidosis: 51% versus 23% in the <65 years of age cohort and 47% versus 15% in the >65 years of age cohort. The corresponding adjusted hazard ratios (HRs) were 2.30 (95% confidence interval [CI], 2.009-2.560; P<.0001) and 4.02 (95% CI, 3.78-4.29; P<.0001). Adjusted HRs per 1 mEq/L increase in HC03 were 0.911 (95% CI, 0.897-0.922; P<.0001) in the <65 years cohort and 0.840 (95% CI, 0.833-0.847; P<.0001) in the >65 years cohort.

“The presence of metabolic acidosis significantly increased the 2-year risk of CKD progression or death in patients with stages 3 to 5 CKD independent of age, sex, diabetes, hypertension, and baseline eGFR,” the researchers said.

Source: Reaven N, Funk S, Mathur V. Adverse clinical outcomes in patients with chronic kidney disease and metabolic acidosis: A longitudinal analysis from electronic medical records of >50,000 patients. Abstract of a presentation at the National Kidney Foundation 2019 Spring Clinical Meetings (Abstract #302).