Delta Procalcitonin Is a Better Indicator of Infection Than Absolute Procalcitonin Values in Critically Ill Patients: A Prospective Observational Study

Purpose. to investigate whether absolute value of procalcitonin (pct) or the change (delta-pct) is better indicator of infection in intensive care patients. materials and methods. post hoc analysis of a prospective observational study. patients with suspected new-onset infection were included in whom pct,c-reactive protein (crp),temperature,and leukocyte (wbc) values were measured on inclusion (t 0) and data were also available from the previous day (t - 1). based on clinical and microbiological data,patients were grouped post hoc into infection- (i-) and noninfection- (ni-) groups. results. of the 114 patients,85 (75%) had proven infection. pct levels were similar at t - 1: i-group (median [interquartile range]): 1.04 [0.40-3.57] versus ni-group: 0.53 [0.16-1.68],p = 0.444. by t 0 pct levels were significantly higher in the i-group: 4.62 [1.91-12.62] versus 1.12 [0.30-1.66],p = 0.018. the area under the curve to predict infection for absolute values of pct was 0.64 [95% ci = 0.52-0.76],p = 0.022; for percentage change: 0.77 [0.66-0.87],p < 0.001; and for delta-pct: 0.85 [0.78-0.92],p < 0.001. the optimal cut-off value for delta-pct to indicate infection was 0.76 ng/ml (sensitivity 80 [70-88]%,specificity 86 [68-96]%). neither absolute values nor changes in crp,temperature,or wbc could predict infection. conclusions. our results suggest that delta-pct values are superior to absolute values in indicating infection in intensive care patients. this trial is registered with clinicaltrials.gov identifier: nct02311816. � 2016 domonkos tr�sy et al.