The effect of fatigue on driving skills in patients with hepatic encephalopathy

Objectives: Hepatic encephalopathy, both overt (OHE) and minimal (MHE), is associated with poor quality of life and fatigue. The aim of this study was to define the effect of fatigue on driving skills in MHE and OHE patients. Methods: Cirrhotics and age/education-matched controls were administered a psychometric battery of tests to diagnose MHE. Cirrhotics with recent OHE on lactulose were also included. All subjects underwent a driving simulation; to assess fatigue, the second half performance was compared with the first half of the simulation. The outcomes were collisions, speeding, road excursions, and center crossings. Actual driving-associated fatigue was assessed by the American Medical Association (AMA) driver survey. Results: A total of 100 cirrhotics (51 MHE, 27 no MHE, and 22 OHE) and 67 controls were included. A significantly higher proportion of OHE and MHE patients admitted to fatigue after actual driving on the AMA survey compared with no MHE patients (P=0.02). All patients who admitted to fatigue and none who denied fatigue on the AMA survey had simulator collisions. Psychometric and simulator performance in treated OHE patients was similarly impaired to MHE patients despite therapy. Within groups, a significant increase in collisions, speeding, and center crossings in the second half (P=0.01) was seen only in MHE patients. Conclusions: Psychometric and simulator performance in patients with recent OHE on treatment is similarly impaired as that of untreated MHE patients. Simulator performance in MHE worsens over time with fatigue. OHE and MHE patients had a higher rate of actual driving-associated fatigue on the AMA survey, which was significantly predictive of simulator collisions.