Indocyanine green clearance as a prognostic marker in acute liver failure

Aims: In patients suffering from acute liver failure (ALF) prediction of prognosis is of major importance to decide whether liver transplantation is needed. The King´s College criteria (KCC) are widely used to determine prognosis. However, the specificity of the KCC to predict the need for transplantation is low. Indocyanine green (ICG) is a dye that is biliary cleared from the blood and its plasma concentration can be determined non-invasively by the rate of absorption of infrared light. The clearance of ICG depends on hepatic blood flow and hepatocyte function.

Methods: Consecutive patients presenting with ALF defined as INR >1.5 and any grade of hepatic encephalopathy in the absence of pre-existing liver disease were analyzed. ICG-clearance was determined daily and the fulfilment of KCC was recorded. ICG-clearance was expressed as percent ICG retention after 15 min (R15). Patients were grouped according to outcome in „spontaneous recovery“ and „liver transplantation or death“.

Results: 27 patients with ALF were analyzed within one year. 20/27 patients (74%) recovered spontaneously, 6/27 patients (22%) underwent liver transplantation, and 1 patient (4%) died. 18/27 patients (67%) fulfilled KCC. Of these patients, 6 underwent transplantation or died (sensitivity 86%, specificity 33%). 9/27 patients (33%) had a R15 >40%. Of these patients, 6 underwent transplantation or died (sensitivity 86%, specificity 67%). 1 patient (4%) was transplanted that did not meet KCC nor had a R15 >40%. Using a cut-off for R15 of 35% yielded a sensitivity of 100% and a specificity of 50%.

Conclusion: Both KCC and ICG-clearance have a high sensitivity to predict the need for liver transplantation in ALF. In contrast, ICG-clearance is far more specific than the application of KCC. The value of the ICG-clearance should be further evaluated in larger trials to prevent unnecessary liver transplants.