Validation of procalcitonin measurement to the side of the stream bed as marking infection in intensive therapy patients

Introduction

Elevation of the serum concentration of procalcitonin (PCT) has been proposed as a marker of disease severity and is associated with systemic infection. This association has led to the proposed use of PCT as a novel biomarker for bacterial sepsis. We sought to evaluate the PCT measurement with culture samples to quickly ratify the sepsis and rapidly begin the use of antibiotics.

Methods

Between September 2006 and March 2007 we evaluated 82 blood samples from 82 patients – 48 males (80.33 ± 10.55 years old) and 34 females (81.17 ± 13.83 years old) – with sepsis or SIRS in the adult ICU of a tertiary hospital. The PCT levels were measured by a quantitative imunoturbidimetry method (PCTL) in ng/ml (Lumitest PCT; Brahms, Germany) and the results compared with a sample culture (blood, urine, tracheal secretion and others).

Results

With the cutoff of PCT levels at 2 ng/ml and positive or negative sample cultures, the analysis found that sensitivity is 37%, specificity is 92%, positive predictive value is 0.84, negative predictive value is 0.40, positive likelihood ratio is 4.62 and negative likelihood ratio is 0.68. With the cutoff of PCT levels at 0.5 ng/ml and positive or negative sample cultures, the analysis found that sensitivity is 72%, specificity is 33%, positive predictive value is 0.54, negative predictive value is 0.48, positive likelihood ratio is 1.07 and negative likelihood ratio is 0.84.

Conclusion

This preliminary analysis suggests that PCT can be used to accurately early identify sepsis only at levels above 2 ng/ml and then decide to rapidly begin the use of antibiotics. In patients with PCT < 2 ng/ml we cannot use PCT to exclude the diagnosis of sepsis. With the cutoff of 0.5 ng/ml we found the same result. Other studies with more samples are necessary to confirm this conclusion.