S.L. Nyberg, E.S. Baskin-Bey, M.M. Mitchell, J.P. Bida, N.K. Schneider, G.E. Smith, T.J. Rosenthal, C.A. Stewart

Pages: 53-62

Abstract
Very little is known about the use of simulated driving to assess neurological impairment in the setting of liver disease. The specific aim this pilot study was to determine if a computerized driving routine could identify individuals judged to be impaired by neuropsychological testing from a population of cirrhotic patients awaiting liver transplantation. Driving performance of cirrhotic patients awaiting liver transplantation (n=15) and healthy volunteers (n=31) was compared in a preliminary evaluation of the Hepatic Encephalopathy Assessment Driving Simulator (HEADS). Cirrhotic patients also underwent standardized neuropsychological testing to assess six cognitive domains (attention, learning, memory, motor, processing speed, visual); impairment of each domain was defined by a Z-score < -1. Thirteen of fifteen cirrhotics were classified as impaired in at least one cognitive domain based on neuropsychological testing. Driving performance of impaired cirrhotics differed significantly from the cohort of non-impaired plus healthy subjects (n=33). Several driving variables showed a strong correlation with impairment of at least one cognitive domain. In contrast, driving performance could not be predicted from MELD score in this population of cirrhotic patients. A computer-simulated driving system such as HEADS may prove useful as a simple and practical means to assess cognitive impairment from liver disease. Further validation is indicated in a larger study population of cirrhotic patients.

Keywords: driver behaviour; impaired driving; cirrhosis; neuropsychological tests; scoring system