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Animal naming test measures hepatic encephalopathy progression

Researchers found that a simplified version of the animal naming verbal response test was an easy, patient-accessible measure for the assessment of hepatic encephalopathy, according to a recently published study.

“Liver cirrhosis may disrupt brain function; however, in daily practice no physician measures it. The maximum number of animals that a patient is able to list in a minute is a simple, no cost, easily obtainable measure of mental function that should be added to everyday hepatologic practice to detect changes in mental function. In addition, it provides information about the risk for hepatic encephalopathy (HE),” Piero Amodio, MD, of the University of Padova, Italy, told Healio.com/Hepatology.

The animal naming test (ANT₁) is a semantic fluency test that consists of listing as many names of animals as possible in 1 minute and is sensitive to cognitive functions related to the prefrontal cortex and anterior cortical areas that become vulnerable to HE in its initial stages.

To standardize the ANT₁, the researchers used a group of 208 healthy individuals as a control cohort. They stratified the individuals by age and education level (elementary school, middle school, high school and university degree). Researchers also enrolled a group of 40 patients with inflammatory bowel disease as a control group. The patient population consisted of 327 patients with cirrhosis. The mean age of the patients was 60 years and they had either a Child-Pugh score of A (40%), B (37%) or C (23%). The patients were followed for 1 year.

In the healthy control cohort, individuals with less than 8 years of education and/or older than 80 years listed a relevantly lower number of animals (P < .001). From this information, the researchers developed a simplified ANT₁ (S-ANT₁) test for patients with fewer years of education or older than 80 years. The S-ANT₁ requires 10 animals to be named for a patient to be considered unimpaired.

“This simplified adjustment of the ANT₁ (S-ANT₁) avoids the complex standardization systems that are usually required for psychometric testing. This procedure produced a very simple classification system in which the person using the test is required to remember only the values of 10 and 15 to score the test, as well as a simple procedure to produce the equivalent score (add three animals for individuals with less than 8 years of education, and six animals if they were, in addition, over the age of 80 years).”

Of the cirrhosis patients, 169 were impaired on the psychometric hepatic encephalopathy score (PHES) system. Seventy-six had minimal HE and 50 had HE grade 1. Eighteen patients had HE grade 2 and 14 had grade 3.

 “Values of less than 15 or, especially, less than 10, are risk indices for minimal HE to exist and for overt HE to occur. Even mortality, together with MELD, was found to be related with this measure,” Amodio said.

The S-ANT₁ results were inversely correlated with the patients’ MELD scores (r = –0.16, P < .025) and ammonia plasma level (r = –0.35, P < .001), and directly correlated with PHES (r = 0.38, P < .001). The average S-ANT₁ score for healthy patients was 23, for the IBD control group it was 25 and for the cirrhosis patients it was 13. Additionally, the S-ANT₁ score was lower in patients with a history of HE grade 2 or higher than in those without (12 vs. 14, P < .03). – by Talitha Bennett

Disclosure: The researchers report no relevant financial disclosures.

Editor’s Note: This article has been updated with additional information from the study author.