Increased Level of Interleukin 6 Associates With Increased 90-Day and 1-Year Mortality in Patients With End-Stage Liver Disease

Abstract

Background & aims: Organ allocation for liver transplantation is based on prognosis, using the model for end-stage liver disease (MELD) or MELD including serum sodium (MELD-Na) score. These scores do not consider systemic inflammation and septic complications. Blood level of C-reactive protein (CRP), in addition to the MELD score, associates with mortality in patients with end-stage liver disease, whereas levels of interleukin 6 (IL6) have not been systematically studied.

Methods: We performed a retrospective observational cohort study of 474 patients with end-stage liver disease (63.5% male; median age, 56.9 years), evaluated for liver transplantation in Germany, with at least 1 year of follow up. Data were collected on blood levels of CRP, IL6, and white blood cell count (WBC). Findings were analyzed in relation to mortality and compared with patients' MELD scores and MELD-Na scores. For survival analysis, the cohort was divided into quartiles of IL6, CRP, and WBC levels, as well as MELD scores. Log-rank test and the Cox proportional hazards regression model were used to compare the groups, and area under the receiver operating characteristic (AUROC) values were calculated.

Results: Blood levels of IL6 and MELD scores associated with mortality: none of the patients with levels of IL6 below the first quartile (below 5.3 pg/mL) died within 1 year. In contrast, 67.7% of the patients in the highest quartile of IL6 level (37.0 pg/mL or more) died within 1 year. MELD score also correlated with mortality: among patients with MELD scores below 8.7, 0.9% died within 1 year, whereas in patients with MELD scores of 18.0 or more, 67.4% died within 1 year. The predictive value of level of IL6 (AUROC, 0.940) was higher than level of CRP (AUROC, 0.866) (P = .009) or WBC (AUROC, 0.773) (P < .001) for 90-day mortality. MELD scores associated with 90-day mortality (AUROC, 0.933) (P = .756) as did MELD-Na score (AUROC, 0.946) (P = .771). Level of IL6 associated with 1-year mortality (AUROC, 0.916) to a greater extent than liver synthesis or detoxification markers international normalized ratio (AUROC, 0.839) (P = .007) or bilirubin (AUROC 0.846) (P = .007). Level of IL6 was an independent, significant risk factor for mortality after adjustment for MELD score, MELD-Na score, level of CRP, or WBC.

Conclusions: In a retrospective analysis, we found high blood levels of IL6 to associate with 90-day and 1-year mortality in patients with end-stage liver disease; its predictive value was comparable to that of MELD or MELD-Na score, and was higher than that of level of CRP or WBC. Further studies should be performed to confirm the results in different cohorts.

Keywords: Acute-On-Chronic Liver Failure; Biomarker; Cirrhosis; Cytokine.