title: Meta-analysis of the association between appendiceal orifice inflammation and appendectomy and ulcerative colitis.
abstract: OBJECTIVE
  This study aimed to investigate the relationship between appendiceal orifice inflammation (AOI) and appendectomy and ulcerative colitis (UC) by a meta-analysis.
  
  
  METHODS
  Databases were thoroughly searched for studies on AOI and UC up to January 2016. Three comparisons were performed: a) whether the previous appendectomy was a risk factor of UC; b) influence of appendectomy on UC courses; c) influence of AOI on UC severity. Odds ratios (ORs) and 95% confidence intervals (CIs) were the effects sizes. The merging of results and publication bias assessment were performed by using RevMan 5.3. Sensitivity analysis was conducted using Stata 12.0.
  
  
  RESULTS
  Nineteen studies were selected in the present study. Results of comparison I showed that appendectomy was a protective factor of UC (OR = 0.44; 95% CI [0.30, 0.64]). Comparison II indicated appendectomy had no significant influence in the courses of UC (proctitis: OR = 1.03, 95% CI [0.74, 1.42]; left-sided colitis: OR = 1.01, 95% CI [0.73, 1.39]; pancolitis: OR = 0.92, 95% CI [0.59, 1.43]; colectomy: OR = 1.38, 95% CI [0.62, 3.04]). Comparison III indicated UC combined with AOI did not affect the courses of UC (proctitis: OR = 1.15, 95% CI [0.67, 1.98]; left-sided colitis: OR = 1.14, 95% CI [0.24, 5.42]; colectomy: OR = 0.36, 95% CI [0.10, 1.23]). Sensitivity analysis confirmed the robust of the results in the present study.
  
  
  CONCLUSIONS
  In conclusion, this meta-analysis indicated appendectomy can reduce the risk of UC. But appendectomy or AOI had no influence on the severity of the disease and the effect of surgical treatment.
authors.affiliation: The Emergency Department, West China Hospital.
authors.forename: Peng
authors.initials: P
authors.lastname: Deng
authors.affiliation: Department of Digestive Internal Medicine, West China Hospital, China.
authors.forename: Junchao
authors.initials: J
authors.lastname: Wu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001062:Appendectomy / Q000706:statistics & numerical data*; D001064:Appendicitis / Q000150:complications / Q000453:epidemiology / Q000601:surgery*; D001065:Appendix / Q000601:surgery; D003093:Colitis, Ulcerative / Q000150:complications* / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012306:Risk; D055815:Young Adult