Validity of Inhibitory Control Test and Critical Flicker Frequency to Diagnose Minimal Hepatic Encephalopathy

Abstract

AIM: Minimal hepatic encephalopathy (MHE) impairs quality of life and predicts overt hepatic encephalopathy (HE) in cirrhotic patients. Recent studies into the inhibitory control test (ICT) and critical flicker frequency (CFF) tests are encouraging since these tests can increase the rate of MHE diagnosis. We aimed to assess the validity of ICT and CFF in the diagnosis of MHE.

MATERIAL AND METHODS: Out of 68 cirrhotic patients, 48.5% (33 patients) were diagnosed as MHE on the basis of psychometric tests. On these 33 patients, ICT and CFF were applied. 35 healthy subjects served as controls for the ICT and CFF.

RESULTS: Taking > 9 lures as positive ICT according to receiver operator characteristic (ROC) curve, the sensitivity, specificity, PPV and NPV were 90.9%, 37.1%, 57.6%, 81.3% respectively. Cirrhotics with MHE had significantly higher lures (22 ± 7.8 vs 11 ± 5.6, p < 0.001) or (56% vs 28%) and lower target response (90% vs 97%) compared with controls. For CFF taking < 37 Hz as cut-off, the sensitivity, specificity, PPV and NPV were 57.5%, 94.3%, 90.5% and 70.2%. We also found that CFF is less time consuming as compare to ICT.

CONCLUSION: ICT and CFF are useful tools to assess MHE. CFF to be less time to consume, less sensitive but more specific than ICT.