title: Allergy is associated with reduced risk of glioma: A meta-analysis.
abstract: BACKGROUND
  Increasing evidences suggest that allergy may reduce the risk of glioma, so it is necessary to perform an up-to-data literature search and investigate this relationship by meta-analysis.
  
  
  METHODS
  We identified the included studies by searching PubMed and Web of Science and excluding irrelevant or ineligible articles. Nineteen studies from 15 articles, including 8435 cases and 118,719 controls, were selected for data extraction and synthesis.
  
  
  RESULTS
  Pooled outcomes showed that there was an inverse association between allergy and risk of glioma (OR=0.64, 95% CI=0.52-0.78, P<0.001). Meanwhile, asthma and eczema would reduce the risk of glioma by 33% and 23% (OR=0.67, 95% CI=0.59-0.75, P<0.001; OR=0.77, 95% CI=0.68-0.86, P<0.001), respectively. Sensitivity analyses confirmed the stability of these findings. Besides, no publication biases were detected regarding all the investigations.
  
  
  CONCLUSIONS
  Overall or specific allergy is protective against glioma. More prospective cohort studies or molecular laboratory experiments are warranted to elucidate the causation and key mechanism.
authors.affiliation: Anhui No. 2 Province People's Hospital, Hefei City, Anhui Province, China; Anhui Prevention and Treatment Center for Occupational Diseases, Hefei City, Anhui Province, China. Electronic address: ahmuzc@sina.cn.
authors.forename: C
authors.initials: C
authors.lastname: Zhang
authors.affiliation: School of Public Health, Anhui Medical University, Hefei City, Anhui Province, China.
authors.forename: Q-X
authors.initials: QX
authors.lastname: Zhu
mesh_terms: D001249:Asthma / Q000453:epidemiology*; D004485:Eczema / Q000453:epidemiology*; D005910:Glioma / Q000453:epidemiology*; D006801:Humans; D006967:Hypersensitivity / Q000453:epidemiology*; D012306:Risk
keywords: Allergy; Asthma; Eczema; Glioma; Meta-analysis