The ROC curves for day-0 and 72-hour PCT concentrations predicted blood culture-positive infections, with AUCs of 0.76 (95% CI 0.66 to 0.86, P < 0.001) and 0.74 (95% CI 0.64 to 0.84, P < 0.001) (Figure 3). Here, CALCA is linked to infection.