Age and seasonality in Hirschsprung-associated enterocolitis risk: a longitudinal cohort study

Hirschsprung-associated enterocolitis (HAEC) remains a major cause of morbidity, with poorly defined triggers and limited modifiable risk factors. Given the roles of immune immaturity and mucosal dysfunction in HAEC pathogenesis, this study evaluated whether age is associated with HAEC risk, and whether seasonal variation consistent with viral exposure is present.

A retrospective cohort study was conducted including patients with HD treated at Children's Hospital Colorado (2008-2021). A piecewise exponential Poisson regression model estimated age-specific HAEC incidence rates, adjusting for Trisomy 21 and length of aganglionosis. Seasonal distribution was assessed using an exact binomial test comparing cold (October-March) versus warm months.

Among 217 patients, 96 HAEC episodes were identified in 53 patients (24.4%). HAEC incidence was highest in the first year of life and declined progressively with age, with an 88% reduction in patients older than 36 months (RR 0.12, 95% CI 0.07-0.22, p < 0.001). Additionally, 60.4% of episodes occurred during cold months, exceeding expected distribution (p = 0.03).

HAEC risk is strongly age-dependent, with a marked reduction after 36 months, supporting a role for immune maturation in disease susceptibility. The observed seasonal pattern suggests that viral exposures may act as triggers in susceptible patients.