Elevated serum S-100β in patients with septic shock is associated with delirium

Abstract

Background: A high prevalence of delirium is observed in sepsis, yet specific markers for this brain dysfunction in sedated patients are still lacking. Cytoplasmic low molecular weight calcium-binding protein, S-100β, is a commonly used nonspecific marker for brain injury. Here, we evaluated whether delirium is associated with increases in S-100β levels.

Methods: This observational study included 22 patients with septic shock. Delirium was assessed by CAM-ICU and blood samples were obtained to measure inflammatory (CRP, PCT, IL-6, IL-17, TNF-α) and cerebral biomarkers (S-100β, NSE, HAB42, SUBP). Patients were categorized according to the presence of delirium.

Results: Delirium was present in 10/22 of the patients (45.5%). Serum S-100β levels were above the laboratory cutoff value of 0.15 μg/L in 13/22 (59.1%) of the patients. The odds ratio for risk of developing delirium in cases with an S-100β >0.15 μg/L was 18.0 (95%CI, 1.7-196.3, P = 0.011). Patients with delirium had higher plasma levels of IL-6 compared to those without; 138.3 pg/mL [28.0-296.7] vs 53.6 pg/mL [109.3-505, P = 0.050]. There was a positive correlation between S100 β and IL-6 levels (r = 0.489, P = 0.021). Delirium patients had higher SOFA scores; 10 [5-9] vs 7[8-10.5], P = 0.036.

Conclusions: Delirium in septic shock was associated with an elevated protein S-100β when using a laboratory cutoff value of 0.15 μg/L and with more severe organ dysfunction during the ICU stay.

Keywords: IL-6; S-100β; brain biomarkers; delirium; encephalopathy; sepsis.