March 18, 2011
Doctors Should Evaluate Liver Disease Patients For Cognitive Impairment, Address Driving Safety
In liver-disease patients, cognitive impairment may not be fully reversible
There are potential legal ramifications for physicians of patients who drive with cognitive impairment, according to a study in Clinical Gastroenterology and Hepatology, the official journal of the American Gastroenterological Association (AGA) Institute.
Between 20 and 60 percent of patients with cirrhosis (a condition in which the liver is permanently scarred or injured by chronic conditions and diseases) are affected by a peculiar kind of cognitive impairment, also known as hepatic encephalopathy (HE), which can range from mild to overt. This impairment can include cognitive alterations with selective attention, visuomotor ability, psychomotor speed and the ability to suppress behavior. Mild HE has also been associated with an increased number of car accidents and traffic violations.
Doctors studied state requirements for reporting HE, and investigated whether lawsuits have been completed against physicians or patients for motor vehicle accidents that were related to HE.
"We found that hepatic encephalopathy is not specifically addressed in any state vehicle code," said Stanley Martin Cohen, MD, of Loyola University Medical Center and lead author of this study. "In the absence of definite laws, the responsibility for identifying potentially hazardous drivers, and the associated liability, might still lie with the physician." To view Dr. Cohen further discuss his research findings, go to http://www.youtube.com/watch?v=eJdkbQvCE_Y.
Dr. Cohen and colleagues contacted motor vehicle departments from all 50 states and examined motor vehicle codes and legal databases to search for HE-related lawsuits. They found that definitions of a medically impaired driver varied considerably. No state specifically mentioned HE or patients with advanced liver disease.
Only six of the states had mandatory reporting laws for drivers who have medical impairments, and 25 of the remaining 44 states provided legal immunity to physicians for reporting such patients. In addition, there were no completed lawsuits against physicians or patients for motor vehicle accidents associated with driving impairment from HE.
"At minimum, physicians and other health-care workers should carefully evaluate their cirrhotic patients for any degree of hepatic encephalopathy and address driving issues with them," added Dr. Cohen.
HE not only affects driving performance, but it is also associated with a reduced quality of life. Even a single episode of overt HE is accompanied by a persistent cognitive defect. In a second study, researchers found that HE is not a fully reversible condition. They evaluated 106 cirrhotic patients for the presence of mild cognitive deficit using a standardized test battery known as the Psychometric Hepatic Encephalopathy Score (PHES), which includes five different psychometric tests.
"Patients with a history of overt hepatic encephalopathy have a persistent cognitive defect despite normal mental status and, in some cases, even despite normal intelligence, aptitude and personality performance evaluated by the Psychometric Hepatic Encephalopathy Score," said Oliviero Riggio, of the Sapienza University of Rome and lead author of this study. "This suggests that the residual cognitive impairment should be examined by specific tests based on the patients' learning capacity."
At clinical examination, all patients were free of overt HE; a total of 27 out of 106 patients had previously experienced at least one episode of overt HE. Based on PHES, patients without prior overt HE were further characterized as affected by mild HE or completely normal.
Patients who previously experienced episodes of overt HE lost their learning capacity when the PHES battery was repeated. On the contrary, in the patients without previous HE, most of the tests and the PHES significantly improved at the second examination. In the group of 27 patients with previous overt HE, there were 19 patients with mild HE and eight with normal PHES. However, in the eight patients without mild HE in whom complete recovery of overt HE may be thought, the repetition of the tests showed the lack of any learning capacity.
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