Song et al. demonstrated that the AUC of PCT for distinguishing septic shock from sepsis was 0.73 (95% CI 0.63–0.83, P < 0.001), and the AUC of PCT for distinguishing sepsis from the control group was 0.80 for PCT (95% CI 0.86–0.96, P < 0.001) [34]. Here, CALCA is linked to Sepsis.