No causal association between inguinal hernia and aortic aneurysm using Mendelian randomization analysis

Aortic aneurysm (AA) is a serious disease that affects the aging population worldwide. Potential risk factors such as inguinal hernia has been suggested by conventional studies could contribute to AA. The aim of our study was to clarify the causal association between inguinal hernia and AA using Mendelian randomization (MR) analysis. Summary statistics data for the associations of inguinal hernia were derived from a recently published large genome-wide association study including 18,791 inguinal hernia cases and 93,955 controls in UK Biobank. Corresponding data of AA were extracted from FinnGen, comprising 7,603 cases and 317,899 controls. The causal association was assessed using MR-egger, weighted median, and inverse variance weighting methods, and compared to observational estimates previously published. Our analysis found no convincing causal effect between genetically predicted inguinal hernia and the risk of AA (odds ratio [OR] = 1.05, 95% confidence interval [CI] = 0.85–1.31, p = 0.65), AAA (OR = 1.15, 95% CI = 0.92–1.46, p = 0.22), and TAA (OR = 1.05, 95% CI = 0.85–1.30, p = 0.67). The results are in contrast to previous observational evidence suggesting a harmful effect of inguinal hernia.