CALCA and bacterial infectious disease: Hatzistilianou et al. (2010) [7] reported PCT’s superior diagnostic performance (94% sensitivity, 96.5% specificity; AUC = 0.875 at ≥2 ng/mL) in neutropenic bacterial infections, significantly outperforming CRP (AUC = 0.702) and IL-8 (AUC = 0.750; p < 0.01).