Utility of Procalcitonin and Interleukin-6 As Severe Infection Biomarkers in Adulthematological and Oncological Patients. Real-Life Single Center Prospective Observational Study

Introduction: Hematological and oncology patients represent a vulnerable population to opportunistic infections, mainly due to the disease itself and chemotherapy-induced neutropenia. Therefore, timely antibiotic treatment becomes of even greater importance in order to prevent sepsis related mortality. Serum C-reactive protein (CRP), procalcitonin (PCT) and interleukin-6 (IL-6) have been widely used to facilitate sepsis diagnosis, but their diagnostic and prognostic values are limited.

Methods: The purpose of our prospective study was to evaluate the diagnostic accuracy of the above-mentioned biomarkers that were monitored during fever episode for early diagnosis of severe infection and sepsis in immunosuppressed patients in course of chemotherapy. Adult oncological or hematological patients with fever or other clinical signs of infectious episode were included in the study. The study was approved by the independent ethics committee and patients provided written informed consent for the acquisition of biomarker samples.

Results: The study population consisted of 51 patients with a median age of 56 year, 59% being male. Around 40% had previous infectious episode including eight patients with sepsis, with 28 patients affected from either lymphoma or multiple

myeloma, while others had oncological disease. The patients were hospitalized in course of study for infectious episode in 40% of cases, while others were receiving chemotherapy with a median hospitalization duration of 12 days. Sixty percent of the study population was in disease progression at study entry.

Fever was present as a clinical sign in all but two patients, that had low-grade fever (<38°C), with 10 patients having neutropenic fever. More than half of the population had body temperature >39°C, with a median of two daily fever spike episodes and median fever duration of two days. Both lung infection in CT scan and positive blood culture were evidenced in approximately 30% of patients. Twelve patients passed away, ten due to infection while disease progression was the cause of death in two of them.Mean baseline and peak PCT values were 4.2 ng/mL and 15.5 ng/mL (range 0.01-150), mean baseline and peak IL-6 values were 262 pg/mL and 299 pg/mL (range 5.5-1500), while mean baseline and peak CRP values were 115 mg/L and 152 mg/L (range 1-775) respectively.

Interestingly, both baseline and peak IL-6 and peak CRP values were associated with survival outcome with p<0.05 (Figure 1A and B) using Wilcoxon-Mann-Whitney test. Furthermore peak CRP values were predictive of blood culture positivity (p=0.0005).

Conclusions: Serum biomarker monitoring in onco-hematological patients with infectious episode can be of aid in order to evaluate the severity and use it as a guide of antibiotic treatment response.

No relevant conflicts of interest to declare.