The psychometric hepatic encephalopathy score (PHES) is composed of five tests, number connection test-A (NCT-A), number connection test-B (NCT-B), serial dotting test (SDT), line tracing test (LTT) and digit symbol test (DST). The results of the NCT-A, NCT-B, and SDT were measured as seconds, including the time needed to correct any errors, and the result of DST was measured as points. The results of the LTT were measured as both the time needed to complete the test (LTTt, seconds) and as the error score (LTTe), LTT = (1 + LTTe/100) × LTTt. Accordingly, a higher result of DST equals better performance, and lower results on the other tests equal better performance.
The final score of PHES is generated from the sum of the scores of five tests, which ranged between +5 and -15. The result of the PHES is expressed in number of standard deviations (SD) from a population matched on age and level of education. A threshold (- 4DS) defines the EHM according to current recommendations.