Metabolic acidosis in patients with nondialysis chronic kidney disease (CKD) are associated with an increased risk of being hospitalized for infection, according to study findings presented at the American Society of Nephrology’s Kidney Week 2021.

“Our findings suggest that clinicians should consider lower serum bicarbonate a risk factor for infection in patients with CKD,” Danielle L. Saly, MD, of Brigham and Women’s Hospital in Boston, Massachusetts, and colleagues concluded in a poster presentation.

In a study of 36,647 patients with nondialysis CKD, 8521 of whom were hospitalized infection, Dr Saly’s team found that a serum bicarbonate level less than 20 mEq/L compared with 28 mEq/L or higher was independently associated with a 23% higher risk of infection requiring hospitalization after adjusting for age, sex, race, and other potential confounders.


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The risk of hospitalization for infection increased as serum bicarbonate levels decreased. Compared with a serum bicarbonate level of 28 mEq/L or higher, levels less of 20-21, 22-23 and 24-25 mEq/L were significantly associated with an 17%, 13%, and 8% increased risk for infection-related hospitalization, respectively.

The study also evaluated the effect of CKD stage on the risk for infection-related hospitalization. Compared with CKD stage 3a, CKD stages 4 and 5 were significantly associated with a 35% and 64% increased risk for infection-related hospitalization, respectively. The investigators defined CKD as 2 estimated glomerular filtration rate values less than 60 mL/min/1.73 m2 at least 3 months apart.

In addition, albuminuria of 300 mg/g or higher was significantly associated with a 29% increased risk for infection-related hospitalization compared with albuminuria less than 30 mg/g.

Metabolic acidosis impairs neutrophil function in patients with end-stage kidney disease via delayed apoptosis, enhanced phagocytosis, and increased oxidative burst reactions, Dr Saly and colleagues explained.

Serum bicarbonate had not previously been studied as a risk factor for infection in patients with nondialysis CKD, the investigators noted.

Study limitations include the retrospective design of the analysis and the inclusion only of patients with a diagnosis code for CKD. Also, as the investigators only captured patients who had an admitting diagnosis or principal diagnosis codes for infection, they may have underestimated the true incidence of infection.

Reference

Saly DL, Strohbehn IA, Sise ME, Curhan GC. Lower serum bicarbonate is a risk factor for hospitalization for infection among patients with CKD. Presented at: Kidney Week 2021, November 2-7, 2021. Presentation PO2353.