Metabolic Acidosis and Progression of CKD in Racial/Ethnic Groups

Metabolic acidosis is a risk factor for progression of chronic kidney disease (CKD). There are few data available on the impact of race and ethnicity on the association between metabolic acidosis and CKD progression. Navdeep Tangri, MD, PhD, FRCP, and colleagues conducted an analysis to examine the relationship between metabolic acidosis and adverse renal outcomes and mortality by race and ethnicity in the United States. Results of the analysis were reported during a virtual poster session at ASN Kidney Week 2020 in a poster titled Relationship Between Metabolic Acidosis and CKD Progression Is Evident Across US Racial and Ethnic Groups.

The researchers utilized a large electronic medical record (EMR) database of >100 million patients from all 50 states in the United States and with all insurance types. The de-identified EMRs covered the period 2007 to 2019 and were used to identify patients with non-dialysis-dependent CKD stages 3-5. Eligible records had ≥2 years of post-index data or death within 2 years; records were grouped by baseline metabolic acidosis (12 to <22 mEq/L) versus normal serum bicarbonate (22 to <30 mEq/L).

The total cohort included 136,067 patients. Of those, 1328 were Asian, 15,248 were Black, 4137 were Hispanic, 111,953 were White, and 3401 were classified as other race/ethnicity. The primary end point of interest was the composite outcome of death, kidney dialysis or transplant, or a 40% decline in estimated glomerular filtration rate (eGFR) from baseline. The impact of serum bicarbonate on the composite outcome was determined using Cox proportional hazards models within each racial/ethnic group, adjusted for age, sex, eGFR, log albumin-to-creatinine ratio, diabetes, hypertension, heart failure, and Charlson Comorbidity Index score.

Of the 136,067 patients, 34.6% (n=47,032) experienced composite outcome events within 2 years: Asian, 35%; Black, 44%; Hispanic, 48%; White, 32%; and other, 48%. Serum bicarbonate was an independent predictor of the composite outcome in all racial/ethnic groups.

Adjusted hazard ratios (HR) for the composite outcome per 1 mEq/L increase in serum bicarbonate (median, 4.2 years; maximum 11.5 years of follow-up) were: Asian, 0.942 (95% confidence interval [CI], 0.917-0.968); Black, 0.976 (95% CI, 0.969-0.983); Hispanic, 0.970 (95% CI, 0.956-0.984); and White, 0.960 (95% CI, 0.957-0.963) (P<.001 for all groups).

In conclusion, the researchers said, “In a large community-dwelling US population, serum bicarbonate was independently associated with adverse kidney outcomes and deaths in Asians, Blacks, Hispanics, and Whites with CKD. Since race and ethnicity are associated with other sociodemographic factors that affect health, further exploration of the potential reasons for the observed range of HRs across these groups is warranted.”

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Source: Tangri N, Mathur VS, Reaven NL, Funk SE, Wesson DE. Relationship between metabolic acidosis and CKD progression is evident across US racial and ethnic groups. Abstract of a poster presented at the American Society of Nephrology virtual Kidney Week 2020 (PO0468), October 22, 2020.

Funding for this poster was provided by Tricida, Inc.