title: Computerized psychometric testing in minimal encephalopathy and modulation by nitrogen challenge and liver transplant.
abstract: OBJECTIVE
  A lack of standardized tests was cited by hepatologists for not testing for minimal hepatic encephalopathy. We therefore compared paper and pencil neuropsychologic tests with a comprehensive computerized assessment (Cognitive Drug Research [CDR], Goring-on-Thames, United Kingdom) of cognitive function.
  
  
  METHODS
  Eighty-nine cirrhotic patients were studied. Composite scores were calculated from the CDR subtests to reflect 5 cognitive domains, and results were validated by comparison with those from 6 standard paper and pencil tests. Level of impairment was defined using the sum of the standard deviations by which each CDR domain (CDR factor score [CDRS]) and each paper and pencil test score (PHES) differed from age-matched norms. CDRS and PHES were repeated in 21 patients after liver transplantation and CDRS in 24 patients after a 108-g amino acid challenge.
  
  
  RESULTS
  There was a high correlation between the 2 assessment methods (r = 0.748; P = .001). Using multiple regression, Model of End-Stage Liver Disease score (P = .011) correlated with PHES. In contrast, the CDR domains Continuity of Attention and Quality of Episodic Memory were significantly related to venous blood ammonia levels (adjusted R(2) = 0.200; F(6,76) = 4.41; P = .001). There were marked deteriorations in the CDR composite scores representing Accuracy of Working (P = .005) and Episodic Memory (P = .001) after amino acid challenge when blood ammonia increased from 63 +/- 36 to 126 +/- 62 micromol/L (P = .001). Both PHES and CDRS returned to the control range after liver transplantation (PHES: pretransplantation, -6; posttransplantation, 0; P < .001; CDRS: pretransplantation, -6; posttransplantation, -2; P = .003).
  
  
  CONCLUSIONS
  CDRS is valuable for the recognition of minimal hepatic encephalopathy.
authors.affiliation: Centre for Liver Research, The Medical School, University of Newcastle upon Tyne, Newcastle upon Tyne, United Kingdom.
authors.forename: Hanan
authors.initials: H
authors.lastname: Mardini
authors.forename: Brian K
authors.initials: BK
authors.lastname: Saxby
authors.forename: Christopher O
authors.initials: CO
authors.lastname: Record
mesh_terms: D000328:Adult; D000368:Aged; D000641:Ammonia / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D003071:Cognition / Q000502:physiology*; D001330:Electronic Data Processing / Q000379:methods*; D005260:Female; D006501:Hepatic Encephalopathy / Q000097:blood / Q000175:diagnosis* / Q000601:surgery; D006801:Humans; D016031:Liver Transplantation / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011594:Psychometrics / Q000379:methods*; D015203:Reproducibility of Results; D012720:Severity of Illness Index
chemical_list: D015415:Biomarkers; D000641:Ammonia