Evaluation of IL-6 for Stepwise Diagnosis of Minimal Hepatic Encephalopathy in Patients With Liver Cirrhosis

Diagnosis of minimal hepatic encephalopathy (MHE) requires psychometric testing, which is time-consuming and often neglected in clinical practice. Elevated Interleukin-6 (IL-6) serum levels have been linked to MHE. The aim of this study was to investigate the usefulness of IL-6 as a biomarker in a stepwise diagnostic algorithm to detect MHE in patients with liver cirrhosis. A total of 197 prospectively recruited patients without clinical signs of hepatic encephalopathy (HE) served as the development cohort. Another independent cohort consisting of 52 patients served for validation purposes. Psychometric Hepatic Encephalopathy Score (PHES) was applied for the diagnosis of MHE. Fifty (25.4%) patients of the development cohort presented with MHE. Median IL-6 levels were more than twice as high in patients with MHE than in patients without HE (16 vs. 7 pg/mL; P < 0.001). On multivariable logistic regression analysis, higher IL-6 levels (odds ratio 1.036; 95% confidence interval [CI] 1.009-1.064; P = 0.008) remained independently associated with the presence of MHE. IL-6 levels ≥ 8pg/mL discriminated best between patients with and without MHE in receiver operating characteristic (ROC) analysis (area under the ROC 0.751). With a cutoff value of ≥7 pg/mL, further elaborate testing with PHES could be avoided in 38% of all patients with a sensitivity of 90% (95% CI 77%-96%) and a negative predictive value (NPV) of 93% (95% CI 84%-98%). This diagnostic accuracy was confirmed in the validation cohort (sensitivity 94%; NPV 93%). Conclusion: Using IL-6 serum levels as a biomarker in a stepwise diagnostic algorithm to detect MHE could substantially reduce the number of patients requiring testing with PHES and in turn the workload. IL-6 may have especially helped in patients who are unable to perform other screening tests.