Aim: Subclinical hepatic encephalopathy (SHE) is a common complication of liver diseases. The aim of this study was to find out the normal value of psychometric test and to investigate the prevalence of SHE in Chinese patients with stabilized hepatic cirrhosis.
Methods: Four hundred and nine consecutive cirrhotic patients without overt clinical encephalopathy were screened for SHE by using number connection test part A (NCT-A) and symbol digit test (SDT). SHE was defined as presence of at least one abnormal psychometric test. The age-corrected normal values were defined as the mean+/-2 times standard deviation (2SD), and developed in 356 healthy persons as normal controls. Four hundred and sixteen patients with chronic viral hepatitis were tested as negative controls to assess the diagnostic validity of this test battery.
Results: There was no significant difference in NCT scores and SDT quotients between healthy controls and chronic hepatitis group (P>0.05). In all age subgroups, the NCT and SDT measurements of cirrhotic patients differed significantly from those of the controls (P<0.05). When mean+/-2SD of SDT and NCT measurements from healthy control group was set as the normal range, 119 cirrhotic patients (29.1%) were found to have abnormal NCT-A and SDT tests, 53 (13.0%) were abnormal only in SDT and 36 (8.8%) only in NCT-A. Taken together, SHE was diagnosed in 208 (50.9%) cirrhotic patients by this test battery. The prevalence of SHE increased from 39.9% and 55.2% in Child-Pugh's grade A and B groups to 71.8% in Child-Pugh's grade C group (P<0.05). After the adjustment of age and residential areas required from the tests, no correlation was found in the rate of SHE and causes of cirrhosis, education level and smoking habit.
Conclusion: Psychometric tests are simple and reliable indicators for screening SHE among Chinese cirrhotic patients. By using a NCT and SDT battery, SHE could be found in 50.9% of cirrhotic patients without overt clinical encephalopathy. The prevalence of SHE is significantly correlated with the severity of liver functions.