Sensitivity and specificity of bispectral index for classification of overt hepatic encephalopathy: a multicentre,...

The severity of hepatic encephalopathy is currently graded clinically using West Haven criteria and psychometric tests.

To assess the discriminative power of the bispectral index (BIS) monitor to classify the degree and progression of hepatic encephalopathy.

A consecutive, multicentre, observer blinded validation study.

Medical University of Graz (Graz, Austria), Zhejiang University First Affiliated Hospital (Hang Zhou, China), and Cairo University (Cairo, Egypt).

28 consecutive patients with hepatic encephalopathy were first enrolled at Medical University of Graz as a test set. The estimated BIS cut off values were subsequently tested in a validation set of 31 patients at Zhejiang University First Affiliated Hospital and 26 patients at Cairo University; 18 patients were reassessed later in a longitudinal study. Fifteen of 85 patients (18%) were excluded from the final analysis (11 became too agitated with high electromyographic activity; four fell asleep during the recording).

Applying the Austrian BIS cut off values of 85, 70, and 55 for discriminating West Haven grades 1 to 4 yielded agreement between BIS classification and West Haven grades in 40 of the 46 validation patients (87%), and in 16 of the 18 follow up patients (89%). Mean (SD) BIS values differed significantly between patients with West Haven grade 1 (90.2 (2.5)), grade 2 (78.4 (6.6)), grade 3 (63.2 (4.8)), and grade 4 (45.4 (5.0)).

BIS is a useful measure for grading and monitoring the degree of involvement of the central nervous system in patients with chronic liver disease.