title: Association between nonalcoholic fatty liver disease and colorectal adenoma: a systematic review and meta-analysis.
abstract: OBJECTIVE
  Several existing studies indicated that nonalcoholic fatty liver disease (NAFLD) may be associated with colorectal adenoma, but the results and risk factors are controversial. A systematic review of studies was conducted to explore these issues by meta-analysis.
  
  
  METHODS
  We searched the Pubmed, Embase, Cochrane library, Medline and Web of Science databases for studies published before May 30(th), 2014. A statistical analysis was performed using RevMan 5.2 software.
  
  
  RESULTS
  Seven studies involving 11,905 participants from different regions were included. Among them, five trials carried out subgroup of NAFLD patients in colorectal adenoma population. The result showed NAFLD was significantly correlated with adenoma of colon (Odds ratio [OR] = 1.56, 95% confidence interval [CI]: 1.22-1.99, P = 0.0003). It could be found in stratified analysis that patients had more chance to get multiple adenomas when they suffered NAFLD (Rate ratio [RR]: 1.52, 95% CI: 1.08-2.13, P = 0.02). Such risk factors of NAFLD as age, waist circumference, body mass index (BMI), disorder of lipid metabolism, hyperglycemia and high blood pressure (HBP) increased risk of colorectal adenoma (Age: mean difference [MD]: 2.81, 95% CI: 0.33-5.28; Waist: MD: 2.84, 95% CI: 2.14-3.54; BMI: MD: 0.85, 95% CI: 0.69-1.01; High-density lipoprotein: MD: -2.46, 95% CI: -3.68 to -1.24; Triglyceride: MD: 16.12, 95% CI: 8.89-23.36; Low-density lipoprotein: MD: 6.04, 95% CI: 3.60-8.48; Cholesterol: MD: 4.25, 95% CI: 0.87-7.63; Fasting glucose: MD: 2.27, 95% CI: 1.24-3.30; HBP: OR = 1.51, 95% CI: 1.22-1.88), while diabetes had no significant association with it (OR = 1.43, 95% CI: 0.94-2.17, P = 0.09). Besides, NAFLD didn't affect the location, size and advanced type of colorectal adenoma (P > 0.05).
  
  
  CONCLUSIONS
  The present systematic review and meta-analysis demonstrated NAFLD was closely associated with great risk of colorectal adenoma and its number, but not with its location, size and advanced type. Waist, obesity, lipid profiles, glucose, hypertension played roles in the process of colorectal adenoma.
authors.affiliation: Department of Gastroenterology, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine Shanghai, China.
authors.forename: Wenjin
authors.initials: W
authors.lastname: Ding
authors.affiliation: Department of Gastroenterology, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine Shanghai, China.
authors.forename: Jiangao
authors.initials: J
authors.lastname: Fan
authors.affiliation: Shanghai Institute of Disaster Prevention and Relief, Tongji University Shanghai, China.
authors.forename: Jianjun
authors.initials: J
authors.lastname: Qin
keywords: Nonalcoholic fatty liver disease; colorectal adenoma; meta-analysis; risk factors