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Filtering-out step may be used in testing for hepatic encephalopathy

The combination of MELD score and critical flicker frequency may be used as a first step to filter-out patients for covert hepatic encephalopathy testing, according to recent findings published in Alimentary Pharmacology & Therapeutics.

“In these patients, further time-consuming diagnostic testing could be avoided,” Christina Ripoll, MD, in the department of internal medicine at Martin-Luther-University Halle-Wittenberg in Germany, and colleagues wrote. “In our study, we evaluate this approach using critical flicker frequency and MELD-Score.”

Using portosystemic encephalopathy syndrome testing to filter-out patients for covert hepatic encephalopathy is costly and not often performed, the researchers wrote. However, the critical flicker frequency test only takes 10 minutes and requires no special training.

To assess this test, Ripoll and colleagues performed a single-center study of 115 patients undergoing portosystemic encephalopathy syndrome and critical flicker frequency testing in 2011. Afterward, they performed logistic regression analysis to identify predictors of hepatic encephalopathy. The researchers defined covert hepatic encephalopathy as an abnormal portosystemic encephalopathy syndrome test.

Sixty-percent had covert hepatic encephalopathy with a higher MELD (16; interquartile range [IQR], 13-21) and lower critical flicker frequency (38 Hz; IQR, 36-41) (P = .0011). In the multivariate analyses, critical flicker frequency (OR = 0.83; 95% CI, 0.74-0.94) and MELD (OR = 1.13; 95% CI, 1.04-1.22) were each identified as predictors of covert hepatic encephalopathy. The sensitivity was 93.5% and the specificity was 42.9% for a critical flicker frequency with a cut-off of 43 Hz and 97.5% and 32.8% for a MELD cut-off of 24. Of all patients, 78% with a MELD score under 24 and a critical flicker frequency greater than 42 Hz did not have covert hepatic encephalopathy and 85% of those with a MELD score greater than 24 and a critical flicker frequency under 43 Hz had covert hepatic encephalopathy. Thus, 27% of patients could avoid further testing with a diagnostic accuracy of 81%.

The researchers concluded that the combination of MELD score and critical flicker frequency can be used to filter-out patients for covert hepatic encephalopathy testing.

One remaining challenge is educating veterans, Graham wrote. As many as one in 10 Vietnam veterans have chronic HCV, a rate five times greater than that of the general population.

“This is clinically relevant, since we believe that a more simple diagnostic process would enhance the readiness to undergo covert hepatic encephalopathy testing,” the researchers wrote. “This easy to perform and easy to interpret approach could be performed as an initial first diagnostic step to pre-select patients in whom further costly and time-consuming psychometric testing could be spared.” – by Will Offit

Disclosure: The researchers report no relevant financial disclosures.