#2196 Trajectories of serum total carbon dioxide and the risk of cardio-renal outcomes in chronic kidney disease: results from the KNOW-CKD study

Abstract Background and Aims Serum bicarbonate levels fluctuate over time in patients with chronic kidney disease (CKD), which may indicate a higher risk for adverse clinical outcomes. However, most studies struggle to analyze the association between baseline levels and outcomes, even with repeated measurements during the observation period. Method This study aimed to perform a time-updated longitudinal analysis to evaluate the association between serum total carbon dioxide (TCO2) levels and long-term clinical outcomes. A total of 1,809 patients from the Korean Cohort Study for Outcome in Patients With Chronic Kidney Disease (KNOW-CKD) were included in the analysis. The median duration of follow-up was 7.9 years. Group-based trajectory modeling (GBTM) was used to classify patients based on their TCO2 levels over time, and Cox regression models were employed to examine the relationship between the trajectory groups and clinical outcomes. Results GBTM identified six distinct TCO2 trajectories, which were subsequently consolidated into three trajectories based on clinical pattern similarities (high, n = 559; intermediate, n = 781; low, n = 469). After adjusting for confounders, patients in the low TCO2 trajectory group had a significantly higher risk of renal outcomes (HR 1.606; 95% CI 1.228–2.101; P < 0.001), while those in the high TCO2 trajectory group showed a reduced risk (HR 0.453; 95% CI 0.305–0.672; P < 0.001). The intermediate TCO2 trajectory group was not associated with renal outcomes, and no significant association was observed between TCO2 trajectories and cardiovascular events. Conclusion This study demonstrated that patients in the low TCO2 trajectory group experienced worse renal outcomes, whereas those in the high TCO2 trajectory group showed improvements in renal outcomes alone, supporting the potential clinical utility of bicarbonate supplementation in patients with CKD.