Venous bicarbonate and CKD progression: a longitudinal analysis by the group-based trajectory model

Area of Science:

• Nephrology
• Internal Medicine
• Clinical Research

Background:

• Metabolic acidosis accelerates chronic kidney disease (CKD) progression in animal models.
• Existing clinical trials on bicarbonate's effect on kidney outcomes are limited.
• Observational studies often rely on single bicarbonate measurements, lacking longitudinal data.

Purpose of the Study:

• To investigate the longitudinal relationship between repeated serum bicarbonate levels and renal outcomes in CKD patients.
• To classify CKD patients into distinct bicarbonate level trajectories using group-based trajectory modeling (GBTM).
• To assess the association between these bicarbonate trajectories and a composite renal outcome.

Main Methods:

• Group-based trajectory modeling (GBTM) was used to identify bicarbonate level patterns over time.
• A cohort of 528 patients with stage 2-5 CKD was analyzed.
• Cox regression models were employed to evaluate the association between bicarbonate trajectories and renal events (eGFR reduction, dialysis, or transplantation).

Main Results:

• Four distinct bicarbonate trajectories were identified: low, moderate, moderate-high, and high.
• A dose-dependent decrease in renal event hazard rates was observed from the lowest to the highest bicarbonate trajectory.
• Patients in the highest bicarbonate trajectory group showed a 63% reduced risk of the composite renal endpoint compared to the lowest trajectory group, after adjustment for confounders.

Conclusions:

• Higher serum bicarbonate trajectories are associated with a significantly lower risk of adverse renal outcomes in patients with CKD.
• Strategies aimed at maintaining higher bicarbonate levels may offer a protective effect against CKD progression.
• Further high-quality randomized controlled trials are necessary to confirm these findings and guide clinical recommendations for bicarbonate supplementation.