The inclusion criteria included (1) study participants (adults ≥18 years of age), (2) intervention (single or serial measurements of serum PCT level from the day of the admission to ICU admission), (3) comparison of the prognostic performance of PCT levels compared to other inflammatory biomarkers or no intervention, (4) outcome (documentation of at least one of the outcomes of sepsis, mortality, or correlation of PCT with the severity of infection), and (5) cohort, case-control, or cross-sectional study designs. Here, CALCA is linked to infection.