Fig. 1

Relationship between [HCO₃⁻] and [Na⁺] − [Cl⁻] at the initiation of ACE-I or ARB. A. Scatter plot of [HCO₃⁻] and [Na⁺] − [Cl⁻]. From the linear regression analysis, [Na⁺] − [Cl⁻] was significantly related with [HCO₃⁻] (r = 0.67 and p < 0.001). B. Receiver operating curve analysis for [Na⁺] − [Cl⁻] for predicting metabolic acidosis ([HCO₃⁻] < 24 mEq/L). From this analysis, 33.5 mEq/L had the highest Yoden indices (sensitivity + specificity − 1). Using this cutoff value, the sensitivity and specificity of [Na⁺] − [Cl⁻] for metabolic acidosis was 75.2% and 75.0%, respectively, while the area under the ROC curve was 0.81 (95% confidential interval 0.78–0.85). [HCO₃⁻], serum bicarbonate level; [Na⁺], serum sodium level; [Cl⁻], serum chloride level; ACE-I, angiotensin-converting enzyme inhibitor; ARB, angiotensin receptor blocker