title: [Meta-analysis on causes of ulcerative colitis].
abstract: OBJECTIVE
  To analyze the main influencing factor of ulcerative colitis (UC).
  
  
  METHODS
  Literature retrieval was conducted by using English databases (PubMed, Cochrane and Embase) and Chinese databases (CNKI, Wanfang, SinoMed and VIP) to collect the studies on the influencing factors of UC published both at home and abroad from January 2000 to October 2014. According to the inclusion and exclusion criteria, data were extracted and methodological quality was assessed. Then, a Meta-analysis was performed with Stata 12.0 software.
  
  
  RESULTS
  A total of 24 case-control studies were included, involving 5 653 patients and 20 218 controls. The results of Meta-analysis showed that the influencing factors of UC would include family history of inflammatory bowel disease, ex-smoker, gastrointestinal infections, regular consumption of milk, fat diet, appendectomy, smoking and high educational level, with the pooled OR values as 4.68 (95%CI:3.59-6.11) , 1.81 (95%CI: 1.58-2.09) , 5.10 (95%CI: 2.38-10.92) , 2.26 (95%CI: 1.65-3.09) , 2.21 (95%CI: 1.49-3.27) , 0.40 (95%CI:0.32-0.51) , 0.44 (95%CI:0.32-0.60) and 0.50 (95%CI:0.36-0.69) , respectively.
  
  
  CONCLUSIONS
  Current evidence showed that the risk factors influencing the incidence of UC were family history of inflammatory bowel disease, ex-smoker, gastrointestinal infections, regular consumption of milk and fat diet, whereas appendectomy, smoking and high educational level were protective factors for UC.
authors: Department of Digestion of the First Hospital of Shanxi Medical University, Taiyuan 030001, China.
authors: Ruili
authors: R
authors: Luo
authors: Department of Digestion of the First Hospital of Shanxi Medical University, Taiyuan 030001, China; Email: mymail5296@163.com.
authors: Lijuan
authors: L
authors: Huo
authors: Department of Digestion of the First Hospital of Shanxi Medical University, Taiyuan 030001, China.
authors: Jie
authors: J
authors: Zhang
authors: Department of Digestion of the First Hospital of Shanxi Medical University, Taiyuan 030001, China.
authors: Qiannan
authors: Q
authors: Zhang
mesh_terms: D016022:Case-Control Studies; D003093:Colitis, Ulcerative / Q000453:epidemiology*; D006801:Humans; D012307:Risk Factors