Diagnostic and prognostic values of critical flicker frequency determination as new diagnostic tool for objective HE evaluation in patients undergoing TIPS implantation

Abstract

The diagnostic and prognostic value of critical flicker frequency (CFF) analysis for assessment of severity and dynamics of hepatic encephalopathy (HE) was studied before and after implantation of a transjugular intrahepatic portosystemic shunt (TIPS). Sixty-three cirrhotic patients were retrospectively analyzed for the consequences of TIPS implantation. Thirty-one cirrhotic patients without TIPS implantation served as age-matched, sex-matched, Child-Pugh-matched controls. CFF and computer psychometric tests as objective test parameters of HE-severity were evaluated for analysis of visual discrimination ability, general arousal and cognitive function. Kaplan-Meier method and Cox proportional hazards regression model were used for analysis of prognostic significances. In the control group, HE-severity was stable during the observation period (442+/-428 days) with minimal changes in CFF (-0.1+/-1.9 Hz). In the intervention group, TIPS implantation had no effect on HE-severity in 44% of the patients and CFF shifted by only 0.01+/-1.5 Hz. Thirty-five and 21% of the patients experienced an aggravation or improvement of HE after TIPS implantation, respectively. In HE improvers CFF increased by 3.3+/-2.3 Hz and decreased by 3.5+/-1.5 Hz in those experiencing an aggravation of HE-severity. Univariate analysis showed that overall survival in the study population inversely correlated with HE-severity and serum alkaline phosphatase activity and positively correlated with serum sodium, albumin and CFF. Serum albumin, alkaline phosphatase levels and CFF were independent predictors of survival in a multivariate Cox regression analysis. The data show that pre-TIPS HE does not predict post-TIPS encephalopathy. Otherwise, CFF can reliably pick up the evolution of HE-severity after TIPS implantation. Low pre-TIPS CFF is indicative for a poor prognosis and may help to identify transplant candidates without delay.