title: Factor V Leiden and inflammatory bowel disease: a systematic review and meta-analysis.
abstract: BACKGROUND
  Recent studies proved that inflammatory bowel disease (IBD) patients had a higher risk of thromboembolism and a Factor V Leiden mutation that prevents the efficient inactivation of factor V, which leads to thromboembolism and thus contributes to a high potential risk of IBD. However, the relationship between Factor V Leiden mutation and IBD remains controversial.
  
  
  METHODS
  We conducted a systematic review with meta-analysis of studies assessing the association of Factor V Leiden mutation with the risk of IBD in humans. We extracted the number of IBD and control subjects with or without Factor V Leiden mutation from each study and conducted this analysis using a fixed-effects model.
  
  
  RESULTS
  Nineteen studies met the inclusion criteria and were included in the meta-analysis. No significant heterogeneity was found in results across the 19 studies (I (2) = 18.8%, P = 0.23), which showed a slight but not significant increase in the risk of IBD with Factor V Leiden mutation in the general population (summary odds ratio [OR] 1.13, 95% confidence interval [CI] 0.87-1.46). Taking into account ethnic differences, further study exhibited a slight but not significant increase in risk of IBD with Factor V Leiden mutation in Europeans (summary OR 1.20, 95% CI 0.88-1.64). However, Factor V Leiden mutation was significantly associated with a higher risk of thromboembolism in IBD patients (summary OR 5.30, 95% CI 2.25-12.48). No publication bias was found in this study.
  
  
  CONCLUSIONS
  This meta-analysis indicated that although Factor V Leiden mutation was not significantly associated with the risk of IBD, it was significantly associated with a higher risk of thromboembolism in IBD patients.
authors.affiliation: State Key Laboratory of Cancer Biology, Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an 710032, Shannxi, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Liang
authors.forename: Shengjun
authors.initials: S
authors.lastname: Wu
authors.forename: Bin
authors.initials: B
authors.lastname: Feng
authors.forename: Shaoni
authors.initials: S
authors.lastname: Lei
authors.forename: Guanhong
authors.initials: G
authors.lastname: Luo
authors.forename: Jingbo
authors.initials: J
authors.lastname: Wang
authors.forename: Kai
authors.initials: K
authors.lastname: Li
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Li
authors.forename: Huahong
authors.initials: H
authors.lastname: Xie
authors.forename: Dexin
authors.initials: D
authors.lastname: Zhang
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
authors.forename: Kaichun
authors.initials: K
authors.lastname: Wu
authors.forename: Danmin
authors.initials: D
authors.lastname: Miao
authors.forename: Daiming
authors.initials: D
authors.lastname: Fan
mesh_terms: D005060:Europe / Q000453:epidemiology; D005165:Factor V / Q000235:genetics*; D020022:Genetic Predisposition to Disease; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000150:complications / Q000453:epidemiology / Q000235:genetics*; D015233:Models, Statistical; D009154:Mutation; D012307:Risk Factors; D013923:Thromboembolism / Q000209:etiology* / Q000235:genetics
chemical_list: C095381:factor V Leiden; D005165:Factor V