Increased risk of appendectomy in patients with gastroesophageal reflux disease: A nested case-control study using a national sample cohort

The purpose of this study is to confirm and complement previous data regarding an association between gastroesophageal reflux disease and appendectomy. The Korean National Health Insurance Service-National Sample Cohort includes data from people ≥ 20 years old collected from 2002 to 2013. A total of 13,484 participants who received an appendectomy were matched with 53,936 controls at a 1:4 ratio. We analyzed the previous histories of gastroesophageal reflux disease (GERD) in the appendectomy and control groups. Appendectomies were identified using operation codes (Q2860-Q2863) exclusive for appendicitis (International Classification of Disease-10 (ICD-10): K35). GERD was defined using the ICD-10 (K21), and patients who were treated ≥ 2 times and were prescribed a proton pump inhibitor (PPI) for ≥ 2 weeks were included. Crude (simple) and adjusted odds ratios (ORs) for GERD and appendectomy were analyzed using conditional logistic regression analyses. A higher GERD rate was detected in the appendectomy group (11.4% [1,713/15,062]) than in the control group (8.2% [4,947/60,248], P < .001). Adjusted ORs for GERD were 1.37 (95% confidence interval [CI] = 1.30–1.45) (P < .001). Subgroup analyses stratified according to age and sex revealed consistent findings. The adjusted OR for GERD in participants prescribed PPIs for ≥ 30 days was 1.31 (95% CI = 1.20–1.43), and the adjusted OR for GERD in participants prescribed PPIs for ≥ 60 days was 1.30 (95% CI = 1.15–1.48). The Odds for GERD were higher in the appendectomy group than in the control group.