The continuous reaction time test for minimal hepatic encephalopathy validated by a randomized controlled multi-modal intervention-A pilot study.

BACKGROUND: Minimal hepatic encephalopathy (MHE) is clinically undetectable and the diagnosis requires psychometric tests. However, a lack of clarity exists as to whether the tests are in fact able to detect changes in cognition. AIM: To examine if the continuous reaction time test (CRT) can detect changes in cognition with anti-HE intervention in patients with cirrhosis and without clinically manifest hepatic encephalopathy (HE). METHODS: Firstly, we conducted a reproducibility analysis and secondly measured change in CRT induced by anti-HE treatment in a randomized controlled pilot study: We stratified 44 patients with liver cirrhosis and without clinically manifest HE according to a normal (n = 22) or abnormal (n = 22) CRT. Each stratum was then block randomized to receive multimodal anti-HE intervention (lactulose+branched-chain amino acids+rifaximin) or triple placebos for 3 months in a double-blinded fashion. The CRT is a simple PC-based test and the test result, the CRT index (normal threshold > 1.9), describes the patient's stability of alertness during the 10-minute test. Our study outcome was the change in CRT index in each group at study exit. The portosystemic encephalopathy (PSE) test, a paper-and-pencil test battery (normal threshold above -5), was used as a comparator test according to international guidelines. RESULTS: The patients with an abnormal CRT index who were randomized to receive the active intervention normalized or improved their CRT index (mean change 0.92 ± 0.29, p = 0.01). Additionally, their PSE improved (change 3.85 ± 1.83, p = 0.03). There was no such effect in any of the other study groups. CONCLUSION: In this cohort of patients with liver cirrhosis and no manifest HE, the CRT identified a group in whom cognition improved with intensive anti-HE intervention. This finding infers that the CRT can detect a response to treatment and might help in selecting patients for treatment.

Effects of common chronic medical conditions on psychometric tests used to diagnose minimal hepatic encephalopathy.

Many chronic medical conditions are accompanied by cognitive disturbances but these have only to a very limited extent been psychometrically quantified. An exception is liver cirrhosis where hepatic encephalopathy is an inherent risk and mild forms are diagnosed by psychometric tests. The preferred diagnostic test battery in cirrhosis is often the Continuous Reaction Time (CRT) and the Portosystemic Encephalopathy (PSE) tests but the effect on these of other medical conditions is not known. We aimed to examine the effects of common chronic (non-cirrhosis) medical conditions on the CRT and PSE tests. We studied 15 patients with heart failure (HF), 15 with end stage renal failure (ESRF), 15 with dysregulated type II diabetes (DMII), 15 with chronic obstructive pulmonary disease (COPD), and 15 healthy persons. We applied the CRT test, which is a 10-min computerized test measuring sustained attention and reaction time stability and the PSE test, which is a paper-pencil test battery consisting of 5 subtests. We found that a high fraction of the patients with HF (8/15, 0.002) or COPD (7/15, p = 0.006) had pathological CRT test results; and COPD patients also frequently had an abnormal PSE test result (6/15, p < 0.0001). Both tests were unaffected by ESRF and DMII. Half of the patients with HF or COPD had psychometrically measurable cognitive deficits, whereas those with ESRF or DMII had not. This adds to the understanding of the clinical consequences of chronic heart- and lung disease, and implies that the psychometric tests should be interpreted with great caution in cirrhosis patients with heart- or lung comorbidity.

Minimal hepatic encephalopathy characterized by parallel use of the continuous reaction time and portosystemic encephalopathy tests.

Minimal hepatic encephalopathy (MHE) is a frequent complication to liver cirrhosis that causes poor quality of life, a great burden to caregivers, and can be treated. For diagnosis and grading the international guidelines recommend the use of psychometric tests of different modalities (computer based vs. paper and pencil). To compare results of the Continuous Reaction time (CRT) and the Portosystemic Encephalopathy (PSE) tests in a large unselected cohort of cirrhosis patients without clinically detectable brain impairment and to clinically characterize the patients according to their test results. The CRT method is a 10-minute computerized test of a patient's motor reaction time stability (CRTindex) to 150 auditory stimuli. The PSE test is a 20-minute paper-pencil test evaluating psychomotor speed. Both tests were performed at the same occasion in 129 patients. Both tests were normal in only 36% (n = 46) of the patients and this group had the best quality of life, a normal CRP, a low risk of subsequent overt HE, and a low short term mortality. Either the CRT or the PSE test was abnormal in a total of 64% of the patients (n = 83), the CRT in 53% (n = 69) and the PSE in 34% (n = 44). All these patients had a poorer quality of life, low-grade CRP elevation, moderate risk for subsequent overt HE, and a higher than 20% short term mortality. Both tests were abnormal in 23% (n = 30) of the patients and this group had more advanced cirrhosis and a 40 % short-term mortality. One of the tests was abnormal in the majority of the patients but concordant in only 60%. Most cirrhosis patients seem to have impairments of different cognitive domains and more domains with advancing disease. Two abnormal tests identified patients with an increased risk of overt HE and death.

The continuous reaction times method for diagnosing, grading, and monitoring minimal/covert hepatic encephalopathy.

Existing tests for minimal/covert hepatic encephalopathy (m/cHE) are time- and expertise consuming and primarily useable for research purposes. An easy-to-use, fast and reliable diagnostic and grading tool is needed. We here report on the background, experience, and ongoing research regarding the continuous reaction times (CRT) method. The method has been in clinical use for decades in Denmark for the stated purpose. The method is a 10-minutes, computerised registration of a series of motor reaction times to an auditory stimulus, with results reported as the CRTindex (50 percentile/(90-10) percentile) as a parameter of reaction time variability. The index is a measure of alertness stability and is used to assess attention and cognition deficits. The CRTindex identifies half of patients in a Danish cohort with chronic liver disease, as having m/cHE, a normal value safely precludes HE, it has a broad outcome span reflecting the degree of brain impairment, it shows no learning effect, and it is independent on age and gender. The CRTindex is, therefore, a candidate tool for routine screening, detecting, grading, and monitoring m/cHE. Still, however, further methodological and clinical validation trials are required and are currently being conducted.