The potential association between appendectomy and non-typhoidal Salmonella (NTS) infection has not been elucidated. We hypothesized that appendectomy may be associated with gut vulnerability to NTS. The data were retrospectively collected from the Taiwan National Health Insurance Research Database to describe the incidence rates of NTS infection requiring hospital admission among patients with and without an appendectomy. A total of 208,585 individuals aged ≥18 years with an appendectomy were enrolled from January 2000 to December 2012, and compared with a control group of 208,585 individuals who had never received an appendectomy matched by propensity score (1:1) by index year, age, sex, occupation, and comorbidities. An appendectomy was defined by the International Classification of Diseases, Ninth Revision, Clinical Modification Procedure Codes. The main outcome was patients who were hospitalized for NTS. Cox proportional hazards models were applied to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs). Two sensitivity analyses were conducted for cross-validation. Of the 417,170 participants (215,221 (51.6%) male), 208,585 individuals (50.0%) had an appendectomy, and 112 individuals developed NTS infection requiring hospitalization. In the fully adjusted multivariable Cox proportional hazards regression model, the appendectomy group had an increased risk of NTS infection (adjusted HR (aHR), 1.61; 95% CI, 1.20–2.17). Females and individuals aged 18 to 30 years with a history of appendectomy had a statistically higher risk of NTS than the control group (aHR, 1.92; 95% CI, 1.26–2.93 and aHR, 2.67; 95% CI, 1.41–5.07). In this study, appendectomy was positively associated with subsequent hospitalization for NTS. The mechanism behind this association remains uncertain and needs further studies to clarify the interactions between appendectomy and NTS.

Background The current study was designed to investigate the association between cholecystectomy and the risk of non‐typhoidal Salmonella (NTS) infection. Methods We obtained claims‐based data from the Taiwan National Health Insurance Research Database (NHIRD) to perform a nationwide cohort study. A propensity score (PS)‐matching analysis was performed with a ratio of 1:2 in the cholecystectomy cohort and cholecystectomy‐free group to reduce selection bias. Both groups were followed until NTS diagnosis, a dropout from the insurance programme or the end of 2013. Cox proportional hazard regression analysis was used to estimate the hazard ratio (HR) and 95% confidence interval (CI) for the risk of NTS infection between the cholecystectomy and cholecystectomy‐free groups. Results Our study enrolled 197 444 patients who had undergone cholecystectomy and 394 888 patients who did not receive cholecystectomy. The adjusted HR (aHR) of NTS infection was 1.34 (95% CI, 1.13‐1.58; P < .001) for the cholecystectomy group after adjusting for demographical characteristics and relevant comorbidities. The study population is predominantly female patients (55%) and older (58% older than 50 years). The subgroup analysis revealed that both sexes and notably, patients aged >50, who underwent cholecystectomy had a higher risk of NTS infection than the matched controls. Follow‐up of patients who underwent cholecystectomy showed that they had a significantly higher risk of NTS infection for more than 6 months after the procedure. Conclusions Our study showed that cholecystectomy might be an independent risk factor for subsequent NTS infection.