Abstract
BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is considered to be a hepatic manifestation of metabolic syndrome (MetS) and the most common chronic liver disease worldwide. The association between NAFLD and colorectal adenoma has been investigated in multiples studies but the results have been conflicting. We performed a systematic review and meta-analysis to evaluate this in asymptomatic patients who underwent screening colonoscopy. METHODS: We searched the literatures of all languages from PubMed, EMBASE and the Cochrane library from January 1, 1980 through July 15, 2014. Combined and subgroup analyses stratified by study designs, study locations, characteristics of adenoma (location, size, number, and advanced adenoma) were performed. RESULTS: Four cross-sectional and one cohort studies with a total of 6,263 subjects were included in the meta-analysis. NAFLD was significantly associated with colorectal adenoma [pooled odds ratio (OR) 1.74, 95% confidence interval (CI): 1.53-1.97]. The association was more significant in Asian population (pooled OR =1.77, 95% CI: 1.52-2.05, n=3 studies), compared to European/North American population (pooled OR =1.42, 95% CI: 0.75-2.67, n=2 studies). NAFLD was significantly associated with the number of colorectal adenoma (pooled OR =1.78, 95% CI: 1.10-2.86, n=2 studies), but not the location, size, or presence of advanced adenoma. CONCLUSIONS: Our results suggest NAFLD is significantly associated with the presence of colorectal adenoma in asymptomatic patients undergoing screening colonoscopy. This finding provides additional risk stratifications for applying colorectal cancer (CRC) screening strategies. However, more studies of western population are needed to further investigate the ethnic disparity.