Metabolic Acidosis Predicts All-Cause Mortality in CKD Patients

Patients with metabolic acidosis face a wide range of adverse outcomes. The association between metabolic acidosis and increased of mortality in patients with chronic kidney disease (CKD) is unclear. Navdeep Tangri, MD, PhD, and colleagues conducted a study to examine this association; results were reported during the NKF Spring Clinical Meetings in a presentation titled Metabolic Acidosis Is a Predictive Factor for All-Cause Mortality in Patients with Chronic Kidney Disease.

Patients with non-dialysis dependent CKD stages 3-5 were identified using de-identified electronic health records from Optum® 2007 to 2017. Inclusion criteria were two or more consistent serum bicarbonate 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; patients who died during the study period were also included.

At 2 years, all-cause mortality was measured in patients with metabolic acidosis compared with patients with normal serum bicarbonate at baseline. Following adjustment for rage, sex, race, diabetes, hypertension, hear failure, Charlson Comorbidity Score, and baseline eGFR and log albumin-to-creatinine ratio (ACR), logistic regression models were used to evaluate the impact of baseline serum bicarbonate on 2-year mortality.

A total of 51,558 patients met inclusion criteria; of those, 17,350 had metabolic acidosis and 34,208 had normal serum bicarbonate at baseline. In unadjusted analysis, the rates of mortality at 2 years were higher in the patients with metabolic acidosis compared with patients without metabolic acidosis: 30.9% vs 10.2%, respectively, P<.001. The comparison remained significant within all stages of CKD (P<.001).

There was an independent association between a 15% higher risk of all-cause mortality and each 1 mEq/L lower serum bicarbonate value: odds ratio, 0.853; 95% confidence interval, 0.846-0.861. In subgroup and sensitivity analyses, the findings were consistent.

In conclusion, the researchers said, “The presence of metabolic acidosis was associated with a high 2-year risk of all-cause death in patients with CKD. This finding was independent of age, sex, race, pre-existing conditions, and baseline eGFR and ACR.”

Source: Tangri N, Reaven N, Funk SE, Mathur V. Metabolic acidosis is a predictive factor for all-cause mortality in patients with chronic kidney disease. Abstract of a presentation at the National Kidney Foundation 2020 Spring Clinical Meetings; abstract #263.