Small Intestinal Bacterial Overgrowth Is a Predictor of Overt Hepatic Encephalopathy in Patients with Liver Cirrhosis

<b>Objective:</b> Liver cirrhosis (LC) progression induces intestinal microbiota abnormalities, such as small intestinal bacterial overgrowth (SIBO), and these changes lead to the inflow of gut pathogens and their degradation products into the vessels, causing cirrhotic complications such as hepatic encephalopathy (HE). <b>Methods:</b> To clarify the relationship between the development of overt HE and SIBO, we conducted a three-year observation after assessment of SIBO in patients with LC. <b>Results:</b> In the analysis of 107 patients, with a mean follow-up duration of 29.4 months, 31 were diagnosed with SIBO and 30 with covert HE. In the Cox multivariate regression analysis for prognosis, the Child-Pugh score, blood urea nitrogen level, and the Union for International Cancer Control (UICC) stage of hepatocellular carcinoma were derived using the following five factors: white blood cell count, blood urea nitrogen level, Child-Pugh score, UICC stage, and serum aspartate aminotransferase and alkaline phosphatase levels (<i>p</i> = 0.002, hazard ratio [HR] 3.733, 95% confidence interval [CI] 1.592-8.754, <i>p</i> = 0.001, HR 1.076, 95% CI 1.030-1.123, and <i>p</i> < 0.001, HR 2.767, 95% CI 1.780-4.302, respectively). Furthermore, in the Cox multivariate regression analysis for overt HE development, covert HE and methane-producing SIBO were derived using the following four factors: methane-producing SIBO, UICC stage, covert HE, and serum ammonia levels (<i>p</i> = 0.038, HR 5.008, 95% CI 1.096-22.892 and <i>p</i> = 0.006, HR 8.597, 95% CI 1.881-39.291, respectively). <b>Conclusions</b>: M-SIBO positivity was a significant predictor of overt HE.