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. MATERIALS AND METHODS: 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. RESULTS: 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). CONCLUSION: 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.