Patients with Minimal Hepatic Encephalopathy Have Poor Insight into Their Driving Skills

Background & Aims: Minimal hepatic encephalopathy (MHE) is associated with impaired driving skills. It is not clear whether patients have insight into this. The Driving Behavior Survey (DBS) is a validated self- or observer-administered questionnaire. DBS consists of a total score (maximum, 104) and an attention-related driving skills section (maximum, 40). DBS was used to compare self-assessment with observer-assessment of driving skills in cirrhotic patients tested for MHE.

Methods: Forty-seven nonalcoholic cirrhotic patients and 40 controls underwent psychometric tests, DBS, and driving simulation with navigation/driving tasks. An adult familiar with the subject's driving completed the DBS independently. Simulator performances, total DBS scores, and driving skill scores were compared between/within groups (MHE+, MHE-, and controls) with respect to self-assessment and observer assessment.

Results: Thirty-six patients were MHE+ and 11 were MHE-. MHE+ had a significantly higher simulator crash (MHE+, 3; MHE-, 1.2; controls, 1.7; P = .001) and illegal turn rate (MHE+, 1.2; MHE-, 0.3; controls, 0.1; P = .0001). Despite this worse performance, MHE+ patients rated themselves similar to MHE- patients and control groups on total (P = .28) and driving skills scores (P = .19). Observer assessment in MHE+ was significantly lower for total (P = .0001) and driving skills (P = .0001) compared with observer assessment for MHE- patients and control groups. MHE+ patients were rated significantly lower on driving skills (34 vs 37; P = .02) and trended lower in the total score (P = .08) by observers compared with self-ratings. In contrast, MHE- and control groups rated themselves similar to their observers on driving skills and total DBS scores.

Conclusions: MHE patients have poor insight into their driving skills. A part of the MHE patient's clinical interview should be to increase awareness of this driving impairment.