The role of hepatic encephalopathy in the era of MELD

Abstract

This issue of Liver Transplantation features an interesting article highlighting the importance of hepatic encephalopathy (HE) in the natural history of patients with advanced liver disease.1 The Model for End-Stage Liver Disease (MELD) scoring system introduced in 2002 determines the allocation of adult livers for transplantation, and does not prioritize patients with HE. This developed from a desire to only use objective measurements for priority listing, and the original statistical analysis leading to adoption of the MELD scoring system did not find a significantly enhancing effect of HE on the predictive accuracy of the MELD. The fact that each of the 3 elements of the MELD scoring system, international normalized ratio, bilirubin, and creatinine in 1 large study correlated with the severity of HE also kept concerns about the absence of HE in the model at bay. 2,3 Later data however, began to emerge suggesting that HE may indeed improve the predictive ability of the MELD score. [4][5][6] This current article by Stewart et al.1 addresses the role of HE upon survival using a large retrospective data set from 2 distinct advanced liver disease populations. The major aims of this study were to establish whether HE was a predictor of survival in cirrhosis and to what extent HE enhanced the predictive accuracy of the MELD scoring system. In this retrospective study by Stewart et al., 1 patients undergoing transjugular intrahepatic portosystemic shunt placement (n ϭ 223), and hospitalized patients with cirrhosis (n ϭ 271) were cared for prior to the MELD era. It is difficult to gauge the impact of this on the accuracy of staging the severity of HE. It is widely believed that the severity of HE was overestimated in the pre-MELD era, which may have influenced the impact of HE on survival. On the other hand, a more standardized estimation of the severity of HE in this one large institutional study may also have occurred. A lingering concern, however, is that there are no documented studies addressing the interobserver variability of the West Haven System for staging the severity of HE.7 Despite the inherent difficulty with retrospective data and the aforementioned issues, the authors clearly found that HE predicts survival in advanced liver disease patients, and HE can increase the accuracy of the MELD score in predicting survival. As the authors further state, however, a prospective validation of these findings is still warranted.Before embarking on a prospective study, additional issues regarding collecting data to gauge the impact of HE upon survival should be resolved, many of which were recently discussed at the MELD Exception Study Group meeting in 2006.8 For example, the concept that a syndrome as complicated as HE can be measured by a single point in time may be flawed. As a result, it was proposed that the length of time spent in the more severe stages of HE should also be documented, assuming a more standardized approach to the measurement of the severity of HE and the overall management of HE occurs. Curren...

The importance of hepatic encephalopathy: Pre-transplant and post-transplant

“…In a previous editorial on HE in Liver Transplantation , Thornton and Mullen4 state “the concept that a syndrome as complicated as HE can be measured by a single point in time may be flawed.” Episodic encephalopathy needs to be differentiated from persistent encephalopathy, and both need to be differentiated from minimal encephalopathy. This would require repeated, periodic reassessment, perhaps at defined intervals.…”