Inhibitory Control Test for the Diagnosis of Minimal Hepatic Encephalopathy

Background & Aims: Minimal hepatic encephalopathy (MHE) is difficult to diagnose. The Inhibitory Control Test (ICT) measures response inhibition and has diagnosed MHE with 90% sensitivity and specificity in a selected population; high lure and low target rates indicated poor ICT performance. We studied the reliability and validity of ICT for MHE diagnosis.

Methods: ICT was compared with a psychometric battery (standard psychometric tests [SPT]) for MHE diagnosis and overt hepatic encephalopathy (OHE) prediction. ICT was administered twice for test-retest reliability, before/after transvenous intrahepatic portosystemic shunting (TIPS), and before/after yogurt treatment. The time taken by 2 medical assistants (MA) to administer ICT was recorded and compared with that of a psychologist for cost analysis.

Results: One hundred thirty-six cirrhotic patients and 116 age/education-matched controls were studied. ICT (>5 lures) had 88% sensitivity for MHE diagnosis with 0.902 area under the curve for receiver operating characteristic. MHE-positive patients had significantly higher ICT lures (11 vs 4, respectively, P = .0001) and lower targets (92% vs 97%, respectively, P = .0001) compared with MHE-negative patients. The test/retest reliability for ICT lures (n = 50, r = 0.90, P = .0001) was high. ICT and SPT were equivalent in predicting OHE (21%). ICT lures significantly worsened after TIPS (n = 10; 5 vs 9, respectively; P = .02) and improved after yogurt supplementation (n = 18, 10 vs 5, respectively; P = .002). The MAs were successfully trained to administer ICT; the time required for test administration and the associated costs were smaller for ICT than for SPT.

Conclusions: ICT is a sensitive, reliable, and valid test for MHE diagnosis that can be administered inexpensively by MAs.