Plasma interleukin-6 levels correlate with survival in patients with bacterial sepsis and septic shock

In this study, IL-6 levels were assessed as inflammatory biomarker of bacterial sepsis in patients hospitalized at the ICU of the hospital of Colombia.

Prospective study on 62 patients diagnosed with sepsis and septic shock. An ELISA assay was used to test serum levels of IL-6 at admission and 48 h after admission. Variables were analyzed by χ2 test (alfa <0.05). Multivariable Cox regression was used to determine the survival with the statistical program SPSS v23.00.

Patient's median age was 53 years old and 59.7% were male. Lung was the most common primary site of infection (43.5%), and hypertension comorbidity with higher prevalence (40%). Infection by Gram negative bacteria were significantly more frequent among patients than Gram positive (P = 0.037). Overall, survival analysis showed that 10 (16.1%) patients died with a survival median of 7.00 +4.874 (2-3) days. In patients with sepsis we detected a significant decline in the average of IL-6 serum levels after 48 h of admission [7.50 (SD: 7.00-68.00) pg/mL vs. 68.00 [SD: 7.00-300.00] pg/mL (P = 0.000). Only 25% of patients with septic shock who presented high levels of IL-6 at the time of admission and at 48 h had a survival up to 15 days (P = 0.005).

We found significant differences between the plasma levels of IL-6 during the first 48 h after admission to the ICU among patients with sepsis and septic shock. Patients with sepsis had a significant decline in IL-6 levels, whereas in patients who developed septic shock, levels of this cytokine remained high and have a lower survival compared to those who maintained low levels of IL-6.