CALCA and bacterial infectious disease: 7 studies of 2,317 patients Evaluation of the use of PCT in the diagnosis of severebacterial infection in young infants (≤3 months of age) 5 of 7 studies used the same cut-off value (0.3ng/mL) RR for diagnosis of severe bacterial infection withincreased PCT was 3.97  RR for diagnosis of severebacterial infection using clinical prediction was 30.6 (patientswithout antibiotic treatment) and 8.75 (patients usingantibiotic)