Animal naming test is a simple and valid tool for detecting covert hepatic encephalopathy and predicting outcomes in Chinese-speaking regions: a preliminary study

BACKGROUND AND AIMS: Hepatic encephalopathy (HE) implies high morbidity and mortality. The assessment of covert HE (CHE) [i.e. minimal HE (MHE) plus grade 1 HE] is often neglected in Taiwan. Therefore, the aim was to investigate the potential of the animal naming test (ANT(1) and simplified ANT(1) (S-ANT(1))) for assessing CHE in Chinese-speaking regions, specifically Taiwan. METHODS: A prospective cohort study was conducted, comprising 65 cirrhotic patients and 29 healthy controls (relatives of the patients). Patients were followed up every three months and censored after two years or until death. Hospitalization for overt HE (OHE) and mortality were considered. All subjects underwent ANT(1), psychometric HE score (PHES), and mini-mental state examination (MMSE). The patients underwent an electroencephalogram (EEG) to detect slowing indicative of MHE. Cut-off values for ANT(1) and S-ANT(1) were assessed by ROC analysis and Youden’s index, considering CHE as a reference. The prognostic values for OHE and OHE-free survival were assessed. RESULTS: Preliminary analysis confirmed that PHES ≤-4 is a good discriminant point for abnormal results. CHE was found in 29 patients: 9 had MHE (PHES ≤ -4 or altered EEG) and 20 had grade 1 HE. ANT(1) and S-ANT(1) were found to have diagnostic values for CHE: AUC = 0.807, 0.786; cut off: 18 and 19, respectively. ANT(1) and S-ANT(1) were found to have prognostic value for OHE, number of hospitalization episodes for OHE, and OHE recurrence-free survival. CONCLUSIONS: ANT(1) KEY MESSAGES: 1. The animal naming test (ANT(1)) is a simple and valid semantic fluency test that can be easily performed in outpatient or bedside settings in one minute and can also be used as a tool for covert hepatic encephalopathy (CHE) detection, quantification, and follow-up in Taiwan, other Chinese-speaking regions, and many other countries. 2. The diagnostic value of ANT(1) and S-ANT(1) for CHE were found to be significant, with area under the receiver operating characteristic curve (AUROC) values of 0.807 and 0.786 respectively, and cut-off scores of 18 and 19. 3. ANT(1) and S-ANT(1) have prognostic value for the first breakthrough of overt hepatic encephalopathy (OHE), number of hospitalization episodes for OHE, and OHE recurrence-free survival, independent of the MELD score.