NPPB and susceptibility to pneumonia measurement: ROC analyses of the sensitivity and specificity to predict 30-day mortality showed areas under the curve of 0.88 (95% CI = 0.82 to 0.94) for NT-proBNP, 0.79 (95% CI = 0.71 to 0.87) for Troponin T, and 0.87 (95% CI = 0.83 to 0.91) for the Pneumonia Severity Index (Figure 3).