Trajectories of Serum Total Carbon Dioxide and the Risk of Cardiorenal Outcomes in Chronic Kidney Disease: Results From the KNOW-CKD Study

초록

Rationale & Objective: Serum bicarbonate concentrations vary over time in chronic kidney disease (CKD), but most studies have focused on baseline values rather than longitudinal trajectories. We aimed to determine the association between long-term patterns of serum total carbon dioxide (tCO2) and adverse renal and cardiovascular outcomes. Study Design: Longitudinal cohort study. Setting & Participants: Patients with CKD enrolled in a prospective cohort with repeated tCO2 measurements. Exposure: tCO2 trajectories identified using group-based trajectory modeling: Low, Intermediate, High, and Improving. Outcome: Renal composite outcome and major cardiovascular events. Analytical Approach: Cox proportional hazards models adjusted for demographic, clinical, and laboratory covariates. Results: Compared with the Intermediate group, the Low trajectory group had higher risk of renal events (HR, 2.08; 95% CI, 1.25-3.46). The High trajectory group showed a trend toward lower renal risk (HR, 0.57; 95% CI, 0.31-1.03), with time-dependent protective effects during prolonged follow-up. The Improving group showed no significant differences in renal or cardiovascular risk but demonstrated a numerically lower incidence of the renal endpoint. Cardiovascular outcomes did not differ across trajectories. Limitations: Observational design and potential residual confounding. Conclusions: Persistent low tCO2 was associated with increased renal risk, whereas high levels conferred delayed protection. The Improving group showed intermediate risk. Longitudinal monitoring of tCO2 may help guide individualized bicarbonate therapy in CKD.

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