Analysis of the specificity and sensitivity of procalcitonin in relation to other markers of inflammation in critically ill patients

Overview

Objective:
To evaluate the diagnostic specificity and sensitivity of procalcitonin (PCT) in comparison with C-reactive protein (CRP) and other inflammatory markers in relation to clinical status and microbiology examinations.

Design:
Prospective study in ICU patients.

Setting:
Department of Anaesthesiology and Intensive Care, University Hospital, 1st Medical Faculty, Charles University, Prague.

Materials and Methods:
164 examinations of PCT, CRP, orosomucoid, prealbumin, fibrinogen, INR, white cell and platelet count were evaluated in 43 patients. APACHE II was calculated on admission, SOFA daily. SIRS, MODS, microbiology findings, blood culture and signs of infection were also assessed. Statistical methods included chi-square, Wilcoxon unpaired test, nonparametric Kruskal-Wallis test, ROC analysis and comparison of area under the curve (AUC).

Results:
AUC higher than 0.6 was recorded in the following variables: MODS: temperature 0.700, PCT 0.683, platelets 0.657. SIRS: temperature 0.852, white cell count (WCC) 0.761, PCT 0.694, fibrinogen 0.612. SOFA: PCT 0.756, platelets 0.711, temperature 0.654, WCC 0.646. Blood culture: albumin 0.703, fibrinogen 0.686, orosomucoid 0.666, temperature 0.649. APACHE: platelets 0.685, PCT 0.605, WCC 0.602. Bacteriology: temperature 0.653, PCT 0.627. Apparent infection: temperature 0.694, fibrinogen 0.680. There was significant difference between survivors and non-survivors in PCT (P = 0.00), platelets (P = 0.00), WCC (P < 0.03) and temperature (P < 0.05).

Conclusion:
PCT was a more effective marker of sepsis-related complications in ICU patients than CRP or other markers of inflammation. ROC analysis was a suitable tool for confirmation of these relations.

Key words:
procalcitonin – C-reactive protein – acute phase reactants – ROC analysis – SOFA – SIRS – MODS