# Appendectomy and Risk of Nonyphoidal Salmonella Infection in Children

## TL;DR

Children who had an appendectomy were found to have a higher risk of developing nontyphoidal Salmonella infection later, suggesting the appendix may help protect against gut infections.

## Contribution

This study is the first to show a significant association between childhood appendectomy and increased risk of nontyphoidal Salmonella infection using a large, nationwide cohort.

## Key findings

- Children who had appendectomy had a 1.58-fold higher risk of nontyphoidal Salmonella infection compared to controls.
- The increased risk was most pronounced in children younger than 5 years (aHR of 2.00).
- The association suggests the appendix may play a protective role in gut immunity against Salmonella.

## Abstract

This cohort study evaluates whether pediatric appendectomy is associated with an increased hazard of subsequent nontyphoidal Salmonella infection.

Is undergoing appendectomy associated with increased risk of developing nontyphoidal Salmonella (NTS) infection in children?

In this nationwide cohort study in Taiwan involving 18 654 children who had an appendectomy and 74 616 children in a matched control group, children who underwent appendectomy had a 1.58-fold higher risk of developing NTS infection compared with the control group.

These findings suggest that appendectomy is associated with a significantly increased risk of future NTS infection in children, suggesting the appendix may play a protective role in gut immunity.

The appendix is thought to have immunological functions. However, its role in protecting against enteric infections such as nontyphoidal Salmonella (NTS) remains unclear in children.

To investigate whether pediatric appendectomy is associated with an increased hazard of subsequent NTS infection.

This was a nationwide population-based cohort study using data from Taiwan’s National Health Insurance Research Database between January 1, 2000, and December 31, 2019. Children who underwent appendectomy were matched to children without appendectomy in a 1:4 ratio based on age, sex and index date. Data were analyzed from January 2000 to December 2019.

Appendectomy during childhood.

The primary outcome was the incidence of NSA infection, defined as 3 outpatient or 1 inpatient diagnosis after the index date. The hypothesis that appendectomy increases susceptibility to NTS infection was specified before data collection. Cox proportional hazards models were used to estimate adjusted hazard ratios (aHRs).

The cohort included 18 654 children who underwent appendectomy (mean [SD] age, 10.04 (4.17) years; 11 883 [63.7%] male) and 74 616 matched children in the control group (mean [SD] age, 9.73 [4.30] years; 47 532 [63.7%] male). Children who underwent appendectomy had a significantly higher risk of NTS infection compared with children in the control group (aHR, 1.58; 95% CI, 1.17-2.13). The risk was pronounced in children younger than 5 years (aHR, 2.00; 95% CI, 1.35-2.97). Regarding follow-up periods, the risk was elevated but not statistically significant for 1 to 4 years (aHR, 1.51; 95% CI, 0.98-2.32) and 5 or more years (aHR, 1.78; 95% CI, 0.89-3.54).

In this nationwide cohort study of children in Taiwan, pediatric appendectomy was associated with an increased hazard of NTS infection in the overall population and in particular among children younger than 5 years. These findings suggest a potential need for surveillance and preventive strategies in children following appendectomy, but further studies are warranted to develop and evaluate specific interventions.