Risk of non-typhoidal Salmonella infection in patients with cholecystectomy

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.