Patients With Minimal Hepatic Encephalopathy Have Poor Insight Into Their Driving Skills

Abstract

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. 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. 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. 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.