Figure 3

ROC curve analyses to determine the optimal cutoff values of KL-6 concentrations in ELF (a) and serum (b) for predicting survival in ARDS patients. The highest KL-6 levels in ELF and serum from each patient were used for the analysis. The vertical axis represents the number of true-positive responses (sensitivity), and the horizontal axis represents the number of false-positive responses (100%-specificity). The area under the curve (AUC) represents the fraction of nonsurviving ARDS patients who would have a positive test (high KL-6 concentration in ELF or serum). The optimal value of KL-6 in ELF was 3453 U/mL, with a sensitivity, specificity, and likelihood ratio of 77.27%, 90.0%, and 7.73, respectively. The optimal value of KL-6 in serum was 530 U/mL, with a sensitivity, specificity, and likelihood ratio of 86.36%, 60.0%, and 2.16, respectively.