A nationwide comparative study of pediatric and adult intussusception in emergency departments during the COVID-19.

Intussusception is a common cause of acute abdominal pain among children presenting to emergency departments, but it is rare in adults, with distinct clinical and epidemiological patterns. However, large-scale comparative data are scarce, and the impact of infectious disease remains poorly understood. We analyzed nationwide emergency department data from South Korea (2019-2023) to compare cross-age clinical characteristics and investigate temporal trends associated with infectious disease incidence, using COVID-19 social distancing as a natural experiment. Among 14,723 cases, 80.8% were pediatric patients, peaking at ages 1-4, while adult cases were evenly distributed. Children presented to higher-level centers, whereas adults required hospitalization with higher clinical acuity. Vomiting and hematochezia predominated in pediatric patients, while abdominal pain and nonspecific symptoms like asthenia and dyspnea were more common in adults. During COVID-19 distancing, pediatric intussusception declined significantly, while adult cases remained stable. Correlation analysis revealed stronger associations of pediatric intussusception with respiratory viruses, particularly adenovirus and rhinovirus, than with enteric pathogens. Causal mediation analysis confirmed that respiratory viruses accounted for 65.6% of the pandemic-associated reduction, with adenovirus (68.3%) and rhinovirus (62.8%) contributing most. These findings highlight age-dependent differences and suggest temporal associations between respiratory viral infections and pediatric intussusception.