Correlation of endotoxin, procalcitonin and C-reactive peptide patterns with ICU admission

Introduction

The ability to stratify patients with evidence of sepsis and to determine appropriate ICU admission is often hampered by inadequate history and a paucity of physical examination findings. The literature is replete with multiple markers used to determine the presence and severity of sepsis. Among the proposed biomarkers, procalcitonin (PCT), C-reactive peptide (CRP) and recently the endotoxin activity assay (EAA) have been proposed as tools to aid in the diagnosis of sepsis from various etiologies. The purpose of this current investigation is to compare baseline EAA levels with PCT and CRP in their ability to correlate with ICU admission above specified levels.

Methods

This is a secondary analysis of a prospective observational study of patients qualifying for early goal-directed therapy for severe sepsis. Emergency department patients enrolled were >18 years old, with at least two SIRS criteria and evidence of infection. From a total of 95 patients (25 nonsevere sepsis and 70 severe sepsis (lactate >4 mmol/l)) who were enrolled, 92 had complete data. Descriptive statistics are provided for ICU and non-ICU patients. Non-normally distributed data for disposition and values for EAA, PCT and CRP were analyzed by Spearman correlation. An alpha level <0.05 was considered statistically significant.

Results

Mean EAA value for patients = 0.54 (SD = 0.23, n = 92), PCT = 19.72 (SD = 54.82, n = 91) and CRP = 122.29 (SD = 94.14, n = 86). Based upon baseline values for EAA (>0.6), PCT (>5 ng/ml) and CRP (>5 mg/l), no statistically significant correlations were found between an elevated EAA, PCT or CRP and ICU admission (P = 0.67, 0.16 and 0.67, respectively). Similarly, the combination of EAA (>0.6) and lactate (>2.0 mmol/l) did not correlate with a significantly higher rate of ICU admissions (P = 0.86). When the maximum level of EAA was followed throughout the first 72 hours of evaluation and treatment, however, there was a trend towards higher ICU admission (P = 0.054).

Conclusion

In this analysis, baseline levels of EAA, PCT and CRP of patients with severe sepsis showed no statistically significant correlation with ICU admission. Evaluation of the maximum value of EAA did display a trend towards higher ICU admission. Possible explanations of this discrepancy may point to heterogeneity in infectious etiologies and presence of comorbidities that complicate interpretation of biomarker data.