Driving simulation can improve insight into impaired driving skills in cirrhosis

Substance‐use simulation impairs driving capability in patients with cirrhosis regardless of hepatic encephalopathy

Driving is independently affected by cirrhosis and hepatic encephalopathy (HE) and alcohol/substance use, but their concomitant impact is unclear. We aimed to determine the impact of alcohol and other substances on driving‐simulator performance in cirrhosis with and without HE. Outpatients with cirrhosis and controls underwent cognitive testing and driving simulation for the following three conditions: baseline, wearing goggles simulating alcohol intoxication, and wearing goggles simulating opioid/benzodiazepine abuse. Outcomes were number of centerline crossings (CCs) and road‐edge excursions (REEs). We compared controls versus patients with cirrhosis then subjects with cirrhosis with and without HE for all conditions, using generalized linear modeling (GLM). Sixty subjects (17 controls, 43 with cirrhosis [Model for End‐Stage Liver Disease score, 10; 21 subjects with prior HE]) were included. Simulations showed higher CCs and REEs at baseline in patients with cirrhosis with and without HE versus controls. With alcohol‐ and substance abuse‐impairment goggles, CCs increased but REEs decreased in cirrhosis. In the GLM, a time and group interaction was seen (p < 0.001) for CCs and REEs. Patients with cirrhosis showed higher CCs and REEs at baseline than controls (CCs, p = 0.003; REEs, p = 0.0001) and higher CCs (p = 0.03) and lower REEs (p = 0.001) with alcohol‐simulating goggles. All groups were equally impaired with opioid/benzodiazepine‐simulating goggles (CCs, p = 0.49; REEs, p = 0.46). Controls with alcohol‐simulating goggles had similar CCs as the baseline of patients with cirrhosis (p = 0.98). conclusions: Simulating alcohol intake induces greater driving impairment in patients with cirrhosis versus controls, but similar patterns were seen with opioid/benzodiazepine‐simulating goggles. At baseline, patients with cirrhosis have simulator outcomes equivalent to intoxicated controls. Driving simulation with goggles modeling substance abuse could improve insight into driving errors and enhance driving rehabilitation in patients with cirrhosis.

The psychomotor vigilance task: Role in the diagnosis of hepatic encephalopathy and relationship with driving ability

BACKGROUND & AIMS

Hepatic encephalopathy (HE) is a syndrome of decreased vigilance and has been associated with impaired driving ability. The aim of this study was to evaluate the psychomotor vigilance task (PVT), which is used to assess both vigilance and driving ability, in a group of patients with cirrhosis and varying degrees of HE.

METHODS

A total of 145 patients (120 males, 59 ± 10 years, model for end-stage liver disease [MELD] score 13 ± 5) underwent the PVT; a subgroup of 117 completed a driving questionnaire and a subgroup of 106 underwent the psychometric hepatic encephalopathy score (PHES) and an electroencephalogram (EEG), based on which, plus a clinical evaluation, they were classed as being unimpaired (n = 51), or as having minimal (n = 35), or mild overt HE (n = 20). All patients were followed up for an average of 13 ± 5 months in relation to the occurrence of accidents and/or traffic offences, HE-related hospitalisations and death. Sixty-six healthy volunteers evenly distributed by sex, age and education served as a reference cohort for the PVT.

RESULTS

Patients showed worse PVT performance compared with healthy volunteers, and PVT indices significantly correlated with MELD, ammonia levels, PHES and the EEG results. Significant associations were observed between neuropsychiatric performance/PVT indices and licence/driving status. PVT, PHES and EEG results all predicted HE-related hospitalisations and/or death over the follow-up period; none predicted accidents or traffic offences. However, individuals with the slowest reaction times and most lapses on the PVT were often not driving despite having a licence. When patients who had stopped driving for HE-related reasons (n = 6) were modelled as having an accident or fine over the subsequent 6 and 12 months, PVT was a predictor of accidents and traffic offences, even after correction for MELD and age.

CONCLUSIONS

The PVT is worthy of further study for the purposes of both HE and driving ability assessment.

LAY SUMMARY

Hepatic encephalopathy (HE) is a complication of advanced liver disease that can manifest as excessive sleepiness. Some patients with HE have been shown to have difficulty driving. Herein, we used a test called the Psychomotor Vigilance Task (PVT), which measures sleepiness and can also be used to assess driving competence. We showed that PVT performance is fairly stable in healthy individuals. We also showed that PVT performance parallels performance in tests which are commonly used in cirrhotic patients to measure HE. We suggest that this test is helpful in quantifying HE and identifying dangerous drivers among patients with cirrhosis.

Covert Hepatic Encephalopathy: Can My Patient Drive?

Liver cirrhosis is a public health problem and hepatic encephalopathy is one of its main complications, which can be either overt meaning thereby evident and readily diagnosed, or covert/minimal (covert hepatic encephalopathy-CHE) needing psychometric testing for diagnosis. Patients with CHE hepatic encephalopathy have deficits in multiple domains including visuospatial assessment, attention, response inhibition, working memory, along with psychomotor speed to name a few areas. These patients have poor navigational skills, get fatigued easily, and demonstrate poor insight into their driving deficits. The combination of all these leads them to have poor driving skills leading to traffic violations and crashes as demonstrated not only on the simulation testing but also in real-life driving events. There are multiple psychometric tests for CHE testing but these are not easily available and there is no uniform consensus on the gold standard testing as of yet. It does not automatically connote that all patients who test positive on driving simulation testing are unfit to drive. The physicians are encouraged to take driving history from the patient and the caregivers on every encounter and focus their counseling efforts more on patients with recent history of traffic crashes, with abnormal simulation studies and history of alcohol cessation within last year. As physicians are not trained to determine fitness to drive, their approach toward CHE patients in regards to driving restrictions should be driven by ethical principles while as respecting the local laws.

Cirrhotic patients have good insight into their daily functional impairment despite prior hepatic encephalopathy: comparison with PROMIS norms

Health-related quality of life (HRQOL) is an important determinant of prognosis in cirrhosis and hepatic encephalopathy (HE). However due to inherent cognitive dysfunction, insight into HRQOL severity in patients with liver disease may be impaired. To assess insight into HRQOL using PROMIS tools compared to norms in cirrhotic patients. PROMIS tools are validated HRQOL instruments that test the domains of anger, anxiety, depression, physical function, pain behavior/impact, sleep disturbances/impairment, and social activities/roles, compared to US-norms. Patients were administered the PROMIS tools, the results of which were reviewed using a visual comparison with thed norms. Then two Likert scales from 0 to 10 per domain were administered that inquired about (1) Surprise Intensity: 0-4: not surprised, 5-10: surprised; and (2) Expectancies: 0-4: results better than expected, 5:10: as/worse than expected. Comparisons between HE/no-HE were also performed. 203 cirrhotic patients (57 yrs., 62 % men, MELD 12, 83 HE) were included. All HE patients were controlled on therapy. Prior HE patients were significantly impaired on all PROMIS domains (p < 0.01) except anger, compared to the re st. The majority (76-85 %) were not surprised with their placement vis-à-vis the norms. Similarly, a majority (59-61 %) thought their results were worse or as expected. However, a third of patients found that their PROMIS results were better than expected. Prior HE status did not significantly impact expectations or surprise based on placement with the norms. The majority of cirrhotic patients, regardless of prior HE, have good insight regarding their HRQOL issues.

In Patients With Cirrhosis, Driving Simulator Performance Is Associated With Real-life Driving

BACKGROUND & AIMS

Minimal hepatic encephalopathy (MHE) has been linked to higher real-life rates of automobile crashes and poor performance in driving simulation studies, but the link between driving simulator performance and real-life automobile crashes has not been clearly established. Furthermore, not all patients with MHE are unsafe drivers, but it is unclear how to distinguish them from unsafe drivers. We investigated the link between performance on driving simulators and real-life automobile accidents and traffic violations. We also aimed to identify features of unsafe drivers with cirrhosis and evaluated changes in simulated driving skills and MHE status after 1 year.

METHODS

We performed a study of outpatients with cirrhosis (n = 205; median 55 years old; median model for end-stage liver disease score, 9.5; none with overt hepatic encephalopathy or alcohol or illicit drug use within previous 6 months) seen at the Virginia Commonwealth University and McGuire Veterans Administration Medical Center, from November 2008 through April 2014. All participants were given paper-pencil tests to diagnose MHE (98 had MHE; 48%), and 163 patients completed a standardized driving simulation. Data were collected on traffic violations and automobile accidents from the Virginia Department of Motor Vehicles and from participants' self-assessments when they entered the study, and from 73 participants 1 year later. Participants also completed a questionnaire about alcohol use and cessation patterns. The driving simulator measured crashes, run-time, road center and edge excursions, and illegal turns during navigation; before and after each driving simulation session, patients were asked to rate their overall driving skills. Drivers were classified as safe or unsafe based on crashes and violations reported on official driving records; simulation results were compared with real-life driving records. Multivariable regression analyses of real-life crashes and violations was performed using data on demographics, cirrhosis details, MHE status, and alcohol cessation patterns, at baseline and at 1 year.

RESULTS

Drivers categorized as unsafe had more crashes and made more illegal turns on the driving simulator than drivers categorized as safe; a higher proportion of subjects with MHE were categorized as unsafe drivers at baseline (16%) than subjects without MHE (7%; P = .02), and at 1-year follow-up (18% vs 0%; P = .02). Alcohol cessation within <1 year and illegal turns during simulator navigation tasks were associated with real-life automobile crashes and MHE in regression analysis; road edge excursions in the simulator were associated with real-life traffic violations. Personal assessment of driving skills improved after each simulation episode.

CONCLUSIONS

In a study of 205 patients with cirrhosis, we associated results from driving simulation tests with real-life driving records and MHE. Traffic safety counseling should focus on patients with cirrhosis who recently quit consuming alcohol and perform poorly on driving simulation.

Treatment of Overt Hepatic Encephalopathy

Hepatic encephalopathy (HE) is defined by an altered mental status in the setting of portosystemic shunting, with or without cirrhosis. The basis of HE is probably multi-factorial, but increased ammonia delivery to the brain is thought to play a pivotal role. Medical therapies have typically focused on reducing blood ammonia concentrations. These measures are moderately effective, but further improvements will require identification of new therapeutic targets. Two medications, lactulose and rifaximin, are currently approved for the treatment of HE in the USA - new compounds are available off-label, and are in clinical trials. The presence of HE is associated with a higher risk of death in cirrhotic patients. Liver transplantation typically cures HE, but HE does not increase the MELD score, and therefore does not contribute to the likelihood of liver transplantation.

Minimal hepatic encephalopathy impairs quality of life

Minimal hepatic encephalopathy (MHE) is the mildest form of the spectrum of neurocognitive impairment in cirrhosis. It is a frequent occurrence in patients of cirrhosis and is detectable only by specialized neurocognitive testing. MHE is a clinically significant disorder which impairs daily functioning, driving performance, work capability and learning ability. It also predisposes to the development of overt hepatic encephalopathy, increased falls and increased mortality. This results in impaired quality of life for the patient as well as significant social and economic burden for health providers and care givers. Early detection and treatment of MHE with ammonia lowering therapy can reverse MHE and improve quality of life.

Differential impact of hyponatremia and hepatic encephalopathy on health-related quality of life and brain metabolite abnormalities in cirrhosis

BACKGROUND & AIMS

Hyponatremia (HN) and hepatic encephalopathy (HE) together can impair health-related quality of life (HRQOL) and cognition in cirrhosis. We aimed at studying the effect of hyponatremia on cognition, HRQOL, and brain MR spectroscopy (MRS) independent of HE.

METHODS

Four cirrhotic groups (no HE/HN, HE alone, HN alone (sodium <130 mEq/L), HE+HN) underwent cognitive testing, HRQOL using Sickness Impact Profile (SIP: higher score is worse; has psychosocial and physical sub-scores) and brain MRS (myoinositol (mI) and glutamate+glutamine (Glx)), which were compared across groups. A subset underwent HRQOL testing before/after diuretic withdrawal.

RESULTS

82 cirrhotics (30 no HE/HN, 25 HE, 17 HE+HN, and 10 HN, MELD 12, 63% hepatitis C) were included. Cirrhotics with HN alone and without HE/HN had better cognition compared to HE groups (median abnormal tests no-HE/HN: 3, HN: 3.5, HE: 6.5, HE+HN: 7, p=0.008). Despite better cognition, HN only patients had worse HRQOL in total and psychosocial SIP while both HN groups (with/without HE) had a significantly worse physical SIP (p<0.0001, all comparisons). Brain MRS showed the lowest Glx in HN and the highest in HE groups (p<0.02). mI levels were comparably decreased in the three affected (HE, HE+HN, and HN) groups compared to no HE/HN and were associated with poor HRQOL. Six HE+HN cirrhotics underwent diuretic withdrawal which improved serum sodium and total/psychosocial SIP scores.

CONCLUSIONS

Hyponatremic cirrhotics without HE have poor HRQOL despite better cognition than those with concomitant HE. Glx levels were lowest in HN without HE but mI was similar across affected groups. HRQOL improved after diuretic withdrawal. Hyponatremia has a complex, non-linear relationship with brain Glx and mI, cognition and HRQOL.

Simple tools for complex syndromes: a three-level difficulty test for hepatic encephalopathy

BACKGROUND

Despite the impact of hepatic encephalopathy on quality of life and prognosis, easily administered tests for its diagnosis are still lacking.

AIM

To assess the usefulness of the Scan package, a three-level-difficulty computerised reaction time test, to diagnose varying degrees of hepatic encephalopathy.

METHODS

Sixty-one cirrhotic patients underwent clinical evaluation, paper-and-pencil psychometry and the Scan package; 32 healthy controls served as reference.

RESULTS

Twenty-nine patients were classified as unimpaired, 15 as having minimal and 17 as having overt hepatic encephalopathy. All healthy controls were able to complete the Scan package; in contrast, the number of patients who were able to complete three/two/one part decreased in parallel with the degree of encephalopathy (χ(2)=17, p=0.01). Reaction times in all three parts increased significantly with the severity of encephalopathy. However, the profile of increase was different [group: F(3,77)=26, p<0.0001; test: F(2,154)=277, p<0.0001; group×test: F(6,154)=7, p<0.0001], with different parts being more/less sensitive to varying degrees of encephalopathy.

CONCLUSIONS

The Scan package seems useful for the diagnosis of hepatic encephalopathy and covers a considerable portion of its spectrum of severity.

Diagnosis and treatment of minimal hepatic encephalopathy to prevent motor vehicle accidents: a cost-effectiveness analysis

Minimal hepatic encephalopathy (MHE) in cirrhosis is associated with impaired driving skills and increased risk of motor vehicle accidents (MVAs). Detection and treatment of MHE has the potential to reduce costs and morbidity associated with MVAs. We conducted a cost-effectiveness analysis to assess the benefits of different strategies of MHE diagnosis and treatment for reducing MVA-related societal costs. The analyses compared five MHE management strategies: (1) presumptive treatment of all cirrhosis patients; (2) diagnosis by neuropsychological exam (NPE) with treatment; (3) diagnosis by standard psychometric tests (SPTs) with treatment; (4) diagnosis by rapid screening using inhibitory control test (ICT) with treatment; and (5) no MHE diagnosis or treatment (status quo). Treatments considered were lactulose or rifaximin, which were assumed to reduce the MVA rate to the level of similarly aged noncirrhosis patients with benefit adjusted for treatment compliance. A Markov model followed a simulated cohort of 1,000 cirrhosis patients without overt hepatic encephalopathy (OHE), from entry into treatment, through MHE development, and later OHE, when they exited the modeled cohort. Follow-up was for 5 years and included biannual MHE testing. The societal cost of a single MVA was estimated at $42,100. All four strategies with lactulose were cost-saving compared with the status quo. Diagnosis with ICT and lactulose was the most cost-effective approach (cost/MVA prevented: $24,454 ICT; $25,470 SPT; $30,469 presumptive treatment and $33,742 NPE). Net program savings over 5 years ranged from $1.7 to 3.6 million depending on the strategy. Rifaximin therapy was not cost-saving at current prices but would become so at a monthly cost of <$353.

CONCLUSION

Detection of MHE, especially using the ICT, and subsequent treatment with lactulose could substantially reduce societal costs by preventing MVAs.