Causal relationship between gastroesophageal reflux disease and 7 types of hernias: A bidirectional Mendelian randomization study.

Gastroesophageal reflux disease (GERD) is linked to various esophageal and extra-esophageal complications. While GERD is theoretically a potential risk factor for abdominal hernias, current evidence is limited. Observational studies have suggested associations between GERD and both congenital diaphragmatic hernia and hiatal hernia. This study employed a bidirectional Mendelian randomization analysis to assess the causal relationship between GERD and 7 types of abdominal hernias. The inverse variance weighting method served as the primary statistical approach, supplemented by sensitivity analyses. Inverse variance weighting results demonstrated significant causal relationships between GERD and increased risks of 5 types of hernias: abdominal wall hernia (odds ratio [OR]: 1.277, 95% confidence interval [CI]: 1.144-1.425, P < .001), umbilical hernia (OR: 1.270, 95% CI: 1.086-1.485, P < .01), incisional hernia (OR: 1.484, 95% CI: 1.261-1.748, P < .001), diaphragmatic hernia (OR: 1.333, 95% CI: 1.171-1.518, P < .001), and hiatal hernia (OR: 1.015, 95% CI: 1.012-1.018, P < .001). No causal links were found with inguinal or femoral hernia. Reverse Mendelian randomization analysis revealed that both diaphragmatic hernia (OR: 1.119, 95% CI: 1.077-1.162, P < .001) and hiatal hernia (OR: 609.061, 95% CI: 83.659-4434.156, P < .001) were causally associated with an increased risk of GERD. Other hernia types showed no significant reverse association. These findings support a bidirectional causal relationship between GERD and specific hernias and may inform improved strategies for diagnosis, treatment, and prevention.