Different body mass index grade on the risk of developing glioma: a meta-analysis

Background: Previous studies reported conflicting results about the risk of developing glioma and different body mass index. So we decided to execute a meta-analysis to solve the dispute. Methods: Comprehensive literature retrieval was carried in PubMed, MEDLINE, and EMBASE up to September 15, 2014. Hand literature information retrieval was not carried. Six studies were fit for this meta-analysis. Pooled hazard ratio (HR) and 95 % confidence interval (CI) of different body mass index grade were performed by fixed/random-effects models, except for normal weight which was referent. Results: Data of 3726 cases were included. Compared with normal weight (20 kg.m < body mass index (BMI) ≤ 24.9 kg.m), the underweight (BMI ≤ 20 kg.m) might have lower incidence on the risk of developing glioma (HR = 1.08, 95 % CI ranged 0.74 to 1.58, P = 0.678). While the overweight (25 kg.m < BMI ≤ 29.9 kg.m) and obesity (BMI ≥ 30 kg.m) were performed as a risk factor of developing glioma. The pooled HR of overweight group was 1.12 (95 % CI ranged 1.02 to 1.22, P = 0.013); the pooled HR of obesity was 1.14 (95 % CI ranged 1.02 to 1.27, P = 0.017). Sensitivity analysis approved that our results were stable. There was no publication bias of these studies. Conclusions: Underweight could decrease the risk of developing glioma. Excess BMI was considered as a risk factor to develop glioma.