Increased risk of gallstones after gastrectomy: A longitudinal follow-up study using a national sample cohort in korea

This study sought to evaluate the association between gastrectomy and the occurrence of gallstones using a national sample cohort from Korea. Data from 2002 to 2013 were collected for individuals ≥20 years of age in the Korean National Health Insurance Service-National Sample Cohort (NHIS-NSC). We extracted data for patients who had undergone gastrectomy (n = 1998) and a 1:4 matched control group (n = 7992) and then analyzed the occurrence of gallstones. The patients were matched according to age, sex, income, region of residence, hypertension, diabetes mellitus, and history of dyslipidemia. Gastrectomies were identified using operation codes (Q2533-Q2537, Q2594-Q2596, and Q2598). Gallstones were diagnosed if the corresponding International Classification of Disease-10 code (K80) was reported ≥2 times. Crude (simple) and adjusted hazard ratios (HRs) were analyzed using Cox proportional hazard models, and 95% confidence intervals (CIs) were calculated. Subgroup analyses were performed based on age and sex. The adjusted HR for gallstones was 1.77 (95% CI = 1.34–2.35, P < .001) in the gastrectomy group compared to control. Consistent HRs were found in the analyses of all of the subgroups determined using age and sex. The occurrence of gallstones was increased in the patients who had undergone gastrectomy compared to their matched control group.