Model performance on the addition of individual biomarkers to the clinical model
| Clinical model# | WBC | ANC | CRP | PCT | |
| Univariable OR (95% CI) | – | 1.08 (0.79–1.48) | 1.38 (1.08–1.76) | 1.94 (1.63–2.32) | 1.09 (0.97–1.21) |
| Multivariable OR (95% CI)# | – | 1.58 (1.07–2.32) | 1.44 (1.06–1.96) | 1.79 (1.47–2.18) | 1.30 (1.13–1.49) |
| C-index | |||||
| Raw | 0.794 | 0.800 | 0.802 | 0.829 | 0.808 |
| Optimism-corrected | 0.780 | 0.783 | 0.786 | 0.812 | 0.795 |
| Diagnostic performance | |||||
| Cutpoint of prediction model ROC curve %¶ | 50.7 | 52.8 | 51.1 | 45.6 | 45.4 |
| Sensitivity % | 57.7 | 59.6 | 60.6 | 70.0 | 65.7 |
| Specificity % | 88.3 | 88.8 | 88.0 | 85.3 | 85.3 |
| PPV % | 74.1 | 75.6 | 74.6 | 73.4 | 72.2 |
| NPV % | 78.3 | 79.1 | 79.4 | 83.0 | 81.1 |
| LR+ | 3.41 | 3.62 | 3.61 | 4.32 | 3.82 |
| LR− | 0.33 | 0.31 | 0.32 | 0.32 | 0.34 |
WBC: white blood cell count; ANC: absolute neutrophil count; CRP: C-reactive protein; PCT: procalcitonin; OR: odds ratio; CI: confidence interval; ROC: receiver operating characteristic; c-index: concordance index; PPV: positive predictive value; NPV: negative predictive value; LR: likelihood ratio. #: includes variables of age, focal decreased breath sounds and duration of fever; ¶: determined by Euclidean distance method.