Actual vs Expected Survival With the Use of the Molecular Adsorbent Recirculating System for Acute Liver Failure

Abstract

Background

Acute liver failure (ALF) has a mortality rate of approximately 50%. Thus, it is evident that improvements in treatment of ALF are necessary. The Molecular Adsorbent Recirculating System (MARS; Baxter), an extracorporeal liver support system that detoxifies water-soluble and protein-bound toxins, has been available at select centers worldwide for > 2 decades. Although some studies have shown the efficacy of MARS in the management of ALF, the literature remains limited. The objective of this study was to assess the outcomes of patients with ALF who underwent MARS therapy at a single institution using institutionally developed indications based on current best evidence.

Research Question

Is MARS used for selected causes of ALF associated with better survivability than predicted by standardized mortality rates (SMRs)?

Study Design and Methods

This was a single-center, retrospective cohort study of the outcomes of patients with ALF who underwent MARS at the R. Adams Cowley Shock Trauma Center, University of Maryland Medical Center. All patients aged 18 years or older who were admitted to our institution and underwent MARS treatment between July 1, 2013, and February 9, 2021, were included in this study. Data relevant to the study were collected from electronic medical records and were stored in Research Electronic Data Capture tools. From these data, estimated mortality from Model for End-Stage Liver Disease scores were used to calculate SMR. The SMRs then were compared for different institutional indications for MARS. Additional descriptive statistics were applied.

Results

Sixty-one patients underwent MARS treatment during the study period. Overall survival in the cohort was 56%. The SMR was lower than expected for patients who underwent MARS who were transplant candidates (SMR, 0.78; 95% CI, 0.63-0.93). Although no significant differences were found before and after MARS treatment in median ammonia levels (58 Umol/L [interquartile range (IQR), 32-104 Umol/L] vs 39 Umol/L [IQR, 18-57 Umol/L]; P = .44) or norepinephrine doses (0.21 μg/kg/min [IQR, 0.08-0.4 μg/kg/min] vs 0.06 μg/kg/min [IQR, 0.04-0.14 μg/kg/min]; P = .46), significant decreases in median aspartate transferase (3,334 U/L [IQR, 1,174-11,151 U/L] vs 344 U/L [IQR, 196-978 U/L]; P < .001), alanine transaminase (1,410 U/L [IQR, 600-5,505 U/L] vs 347 U/L [IQR, 153-952 U/L]; P < .001), international normalized ratio (3.2 [IQR, 2-4.5] vs 1.5 [IQR, 1.3-1.9]; P < .001), and median lactic acid levels (7.7 mM [IQR, 4.8-13.2 mM] vs 2.4 mM [IQR, 1.7-3.1 mM]; P < .001) were seen.

Interpretation

We report our experience using MARS for institutionally developed indications in a level 1 trauma center and transplant center. These data add to a growing body of literature that support the use of MARS as an extracorporeal life support method for selected patients at centers experienced in the management of advanced liver disease.