Interleukin-6 and its association with outcome in traumatic brain injury: a prospective cohort

Traumatic brain injury (TBI) continues to be a major cause of death and disability worldwide. Biomarkers for treatment and prognostication are needed for counseling and clinical management.

In this study, we evaluated the ability of serum IL-6 to predict mortality and disability in a population whith moderate and severe TBI (msTBI).

Adult patients with msTBI were included consecutively from December 2019 to August 2023. Clinical data were collected during hospital stays and functional outcome was established at 6 months using GOSE. Serum IL-6 levels were measured on day 0, day 3 and day 7 after injury.

Eighty-eight patients were recruited and completed 6-month follow-up. Clinical variables associated with the 6-month adverse outcome were admission GCS (OR 0.77 95% CI 0.67-0.87, p < 0.001), age (OR 1.10 95% CI 1.03-1.1, p = 0.001), Rotterdam score (OR 2.8 95% CI 1.7-5.0, p < 0.001), hospital infections (OR 4.7 95% CI 1.9-12.1, p < 0.001) and day-0 IL-6 (OR 1.1 95% CI 1.08-1.13, p < 0.001). When adjusted for age, severity of injury,and the presence of a hospital infection, day-0 IL-6 was significantly associated with the adverse outcome at 6 months (OR 1.15 95% CI 1.1-1.2, p = 0.031). Area under the curve (AUC) of 89% (95% CI 82%-96%). Calculated sensitivity and specificity were 75% and 89%, respectively, at a cut-off point of 59 pg/ml.

In a population of msTBI, levels of serum interleukin-6 within the first 24 h after injury is an independent predictor of 6-month mortality and disability with a net benefit in clinical decision-making across relevant threshold probabilities.