Updating the neuropsychological test system in Japan for the elderly and in a modern touch screen tablet society by resetting the cut-off values

Aim: Covert hepatic encephalopathy is frequently seen in cirrhotic patients. This condition can be diagnosed by a computerized neuropsychological test system (NPT); however, NPT has not been updated for approximately two decades in Japan. The aim of this study is to update the NPT to be more suitable for both the elderly and modern society by resetting of cut-off values.

Methods: We enrolled 367 healthy subjects aged between 40 and 79 years old between 2003 and 2010. The NPT consists of the following eight tests: number connection tests (NCT)-A and -B, a figure position test, a digit symbol test, a block design test, and reaction time tests (RTT)-A, -B, and -C. All subjects were classified into eight groups (5-year quartile ranges from 40 to 79 years old), and the cut-off value for each test was compared to the former cut-off value (NPT version 1).

Results: In all eight tests, most of the cut-off values were different from those in NPT version 1. The difference was minimal in RTT-A, RTT-B, and RTT-C. However, the difference was evident in the NCT-A, NCT-B, digit symbol test, and block design test. In particular, a 57.8-s decrease in the cut-off value was seen in the 65-69-year-old group for the NCT-B test (71.3 s vs. 129.1 s).

Conclusions: We updated the NPT by covering subjects aged 40-79 years and resetting the cut-off values. Thus, the updated NPT is an elderly and modern subject-compliant application. This update may improve the diagnostic ability of covert hepatic encephalopathy in contemporary cirrhotic patients.