A new diagnostic and severity marker in patients with SIRS, sepsis, severe sepsis and septic shock; procalcitonin

Although the exact origin of procalcitonin (ProCT) in infection remains unclear, its association with the presence and severity of infection has been demonstrated. This prospective study aims to evaluate ProCT as a diagnostic marker of infection in critically ill patients with SIRS, and to investigate the relationship of ProCT levels with sepsis severity and outcome.

The study included 85 consecutive adult patients, fulfilling the criteria of inflammatory response, admitted to the ICU at the Istanbul University Hospital. The clinical state of the patients was defined on the basis of clinical, laboratory and bacteriological findings as SIRS, sepsis, severe sepsis and septic shock according to the consensus criteria. Data were collected including temperature, heart rate, respiratory rate, arterial pressure, WBC count, ProCT, and CRP on each ICU day. The severity of sepsis was recorded by SOFA score and the organ system failure by MODS score. Correlation of ProCT values with severity indices were done by Spearman correlation analysis and to compare independent samples we used Mann Whitney U-test. ROC curves and area under the curves of ProCT, CRP, and WBC in diagnosing infection and prognosticating sepsis outcome, were calculated.

Compared with CRP, ProCT had a higher sensitivity (0.35 vs 0.73) and specificity (0.42 vs 0.81) in identifying infection in SIRS with a best cutoff level of 1.31 ng/ml for ProCT and 13.9 mg/dl for CRP. Parallel to SOFA and MODS scores, there was a consistent increase in ProCT levels with sepsis severity (Table 1).

Plasma ProCT values were higher in nonsurvivors in septic patients, and area under the ROC curve of ProCT in prognosticating outcome was higher than for both CRP and WBC. The present data demonstrated ProCT as a better diagnostic marker of infection in patients with inflammatory response. This laboratory procedure also seemed to be closely correlated with sepsis severity and outcome.

Table 1 Table 1