Diagnostic value of procalcitonin and IL-6 for sepsis of older patients and other patients in the emergency department

Introduction

Emergency physicians are able to identify severely ill older patients with SIRS in the emergency department (ED). A previous study showed that elevated procalcitonin (PCT) and IL-6 level is a known marker of sepsis and predicts bacteremia and mortality. We assessed the diagnostic value of PCT and IL-6 in older patients and other patients with SIRS and sepsis in the ED.

Methods

This retrospective cohort study was conducted from January 2013 to December 2013. We enrolled 122 patients with SIRS, 55 were classified as the older age group (>65 years of age). Measurement of serum PCT, IL-6, and white blood cell count was performed on initial admission to the ED. We analyzed these markers in older patients and other patients groups with sepsis.

Results

Of the 55 patients in the older group 33 (60%) patients had sepsis, and 40 (59.7%) patients of the other group had sepsis. PCT and IL-6 levels were significantly higher in other patients with sepsis (P < 0.001, P < 0.001). But PCT and IL-6 levels were not higher in old age patients with sepsis (P = 0.400, P = 0.169). The area under the receiver operating characteristic curve (AUC) for diagnosis of sepsis according to PCT and IL-6 was 0.823, and 0.772 for the other patients group. The diagnostic sensitivity, specificity, positive predictive value, and negative predictive value of PCT for sepsis in other patients group were 79.5%, 81.5%, 86.1%, and 73.3% respectively, with a PCT cutoff value of 0.18 ng/ml. The diagnostic sensitivity, specificity, positive predictive value, and negative predictive value of IL-6 for sepsis in other patients group were 67.5%, 81.5%, 84.4%, and 62.9% respectively, with a IL-6 cutoff value of 74.43 pg/ml.

Conclusion

PCT and IL-6 is useful predictive markers for diagnosing sepsis in adult patients (<65 years of age) with SIRS in the ED. But these markers are not useful for identification of sepsis in older patients.