Causal inference study on the influence of anemia indicators on the incidence of allergic rhinitis: two- sample Mendelian randomization

Anemia and allergic rhinitis (AR) are prevalent clinical conditions in children. Previous studies have suggested an association between anemia and AR. Using Mendelian randomization (MR) analysis, we investigated causality with regard to the influence of anemia indicators on the incidence of AR. We searched the IEU OpenGWAS database for summary information on genome-wide association studies (GWAS) of anemia and AR in European populations. Three methods, MR-Egger, weighted median (WM), and inverse variance weighted (IVW), were utilized to evaluate the causal link between SLE and thyroid disease. We assessed pleiotropy and heterogeneity using MR-Egger intercept, MR-PRESSO, and Cochran’s Q test, among others. The IVW model revealed a significant causal association between anemia and AR. As the severity of anemia increased (OR = 1.02, p < 0.05), the risk of AR also increased. Moderate heterogeneity was observed (Cochran’s Q p-value < 0.05; 25% > I ²  > 50%) among significant anemia-associated indicators in the MR results of AR (IVW). The MR-Egger regression was used to assess the horizontal pleiotropy of the instrumental variables. The statistical hypothesis test P-values of the intercept terms of each index exceeded 0.05, and the intercept was close to zero, indicating that the causal inference in this study was unaffected by horizontal pleiotropy. The MR analysis results support a potential causal link between anemia and AR, suggesting that anemia is a risk factor for AR. These insights could contribute towards raising awareness regarding the pathogenesis of AR and aid the formulation of strategies for its prevention, treatment, and prognosis.