Causal Relationship Between Body Mass Index and Risk of Otitis Media with Effusion in Children: A Mendelian Randomization Study.

Background: Body mass index(BMI) in children appears to be associated with Otitis media with effusion(OME) in observational studies, but the causal relationship is not clear. Methods: A two-sample Mendelian randomization (MR) study was used to explore the causal relationship between childhood BMI and OME in people of European ancestry. Genome-wide association studies (GWAS) of childhood BMI were used as exposures (n = 61,111), while GWAS of OME were used as outcomes (n = 429,290). The weighted inverse variance method (IVW) was used as a baseline method to test for causality. In addition, MR-Egger, simple mode analysis, weighted median, and weighted mode were used as complementary methods.MR-PRESSO analysis, MR-Egger intercept analysis, and Cochran's Q statistical analysis were also used to detect possible directional heterogeneity and polymorphism. To assess this association, we used ratios (OR) with 95% confidence intervals (ci). All statistical analyses were performed in R. Results: We selected 22 genome-wide significant single nucleotide polymorphisms (SNPs) from GWAS as instrumental variables (IVW). the IVW approach showed evidence supporting a causal relationship between BMI and OME in children (β = 0.265, SE = 0.113, P = 0.018). MR-Egger regression showed that targeted polymorphisms were unlikely to bias the results bias (intercept=-0.022; P = 0.488), but there was no causal relationship between BMI and OME (β = 0.584, SE = 0.465, P = 0.224). Although the results of the IVW and MR Egger analyses were not consistent, the IVW analysis maintained higher precision, and the Cochran Q test, heterogeneity and polymorphism tests showed no heterogeneity, no directionality and no polymorphism. Conclusions: MR studies suggest that genetically predicted body mass index in childhood is associated with an increased risk of OME. Notably, given the limitations of this study, the mechanism of association between body mass index and OME in childhood needs further investigation. These results support the importance of effective management of obesity, which may reduce OME occurrence and decrease OME recurrence.