Venous bicarbonate and ckd progression: a longitudinal analysis by the group-based trajectory model
Graziella D'Arrigo, Mercedes Gori, Daniela Leonardis, Giovanni Tripepi, Francesca Mallamaci, Carmine Zoccali- Transplantation
- Nephrology
Abstract
Background
Metabolic acidosis accelerates chronic kidney disease (CKD) progression towards kidney failure in animal models. Clinical trials testing the effect of bicarbonate on kidney outcomes are either underpowered and/or of suboptimal quality. On the other hand, observational studies testing the same hypothesis are generally based on bicarbonate measured just at a single time point.
Methods
We studied the longitudinal relationship between repeated venous bicarbonate levels and a predefined composite renal outcome (a ≥ 30% eGFR reduction, dialysis or transplantation) by using group-based trajectory model analysis (GBTM). The GBTM analysis was used to classify patients based on individual bicarbonate levels over time. The relationship between trajectory groups and renal outcomes was investigated using crude and adjusted Cox regression models. A total of 528 patients with stage 2–5 CKD were included in the analysis.
Results
. The GBTM analysis identified four distinct trajectories of bicarbonate levels: low, moderate, moderate-high, and high. During the follow-up period, 126 patients experienced the combined renal endpoint. The hazard rate of renal events decreased dose-dependent from the lowest to the highest bicarbonate trajectory. After adjusting for potential confounders, there was a 63% risk reduction for the composite renal endpoint for patients in the high bicarbonate category compared to those in the low trajectory.
Conclusion
The study found that higher bicarbonate trajectories were associated with a lower risk of adverse renal outcomes in CKD patients. These results suggest that strategies to maintain higher bicarbonate levels may benefit patients with CKD. However, further high-quality randomised trials are needed to confirm these findings and recommend bicarbonate supplementation as a strategy to delay CKD progression.