Prevalence and Characteristics of Covert/Minimal Hepatic Encephalopathy in Patients With Liver Cirrhosis: A Systematic Review and Meta-Analysis

INTRODUCTION: Covert/minimal hepatic encephalopathy (C/MHE) is the mildest form of hepatic encephalopathy (HE), but it is closely related to the quality of life and prognosis of patients with cirrhosis. Currently, the epidemiological data of C/MHE have not been well described. METHODS: We searched the PubMed, Embase, and Cochrane Library databases for relevant articles. We performed a random-effects meta-analysis of proportions to estimate the pooled prevalence of C/MHE in patients with cirrhosis. We also examined potential risk factors for C/MHE by comparing characteristics of patients with and without C/MHE. RESULTS: Finally, a total of 101 studies were included. The prevalence of C/MHE was 40.9% (95% confidence interval, 38.3%–43.5%) among patients with cirrhosis worldwide. The pooled C/MHE prevalence was 39.9% (95% confidence interval 36.7%–43.1%) based on studies using the psychometric HE score as a diagnostic tool. Meta-regression models showed that geographic region, sample size, mean age, sex ratio, and Child-Pugh classification were influencing factors for the heterogeneity of C/MHE prevalence. The presence of C/MHE was found to be associated with various factors including age, level of education, alcoholic etiology, Child-Pugh classification, MELD score, history of overt HE, presence of other complications, and laboratory tests related to impaired liver function. DISCUSSION: This study reports detailed data on the prevalence of C/MHE as well as clinical features associated with C/MHE, suggesting that C/MHE is one of the most common complications of liver cirrhosis.