Fig. 2

Receiver operating characteristic (ROC) curves for procalcitonin were reconstructed in 4 models. In Model 1, the estimated area under the curve (AUC) for procalcitonin was calculated at 0.89 (95% CI 0.82–0.95) by univariate logistic regression. The AUC of Model 2 was increased to 0.92 (95% CI 0.86–0.97), the sensitivity was 88% and the specificity was 88%. In Model 3, the AUC was decreased to 0.7 (95% CI 0.56–0.83), which was associated with a sensitivity of 56% and specificity of 88%. Finally, Model 4 revealed that the AUC was 0.89 (95% CI 0.83–0.95) by the sensitivity of 85% and specificity of 90%