Allergy reduces the risk of meningioma: a meta-analysis.

Meningiomas are the most common brain tumours; however, little is known regarding their aetiology. The data are inconsistent concerning atopic disease and the risk of developing meningioma. Thus, we conducted a meta-analysis to investigate the association between allergic conditions and the risk of developing meningioma. A systematic literature search was conducted using PubMed and Web of SCI from Jan 1979 to Feb 2016. Two investigators independently selected the relevant articles according to the inclusion criteria. Eight case-control studies and 2 cohort studies were included in the final analysis, comprising 5,679 meningioma cases and 55,621 control subjects. Compared with no history of allergy, the pooled odds ratio (OR) for allergic conditions was 0.81 (0.70-0.94) for meningioma in a random-effects meta-analysis. Inverse correlations of meningioma occurrence were also identified for asthma and eczema, in which the pooled ORs were 0.78 (0.70-0.86) and 0.78 (0.69-0.87), respectively. A reduced risk of meningioma occurrence was identified in hay fever; however, the association was weak (0.88, 95% CI = 0.78-0.99). The source of this heterogeneity could be the various confounding variables in individual studies. Overall, the current meta-analysis indicated that allergy reduced the risk of developing meningiomas. Large cohort studies are required to investigate this relationship.