Exploring the Infectious Contribution to Intussusception Causality Using the Effects of Coronavirus Disease 2019 Lockdowns in Australia: An Ecological Study

Background. Intussusception is the primary cause of acute bowel obstruction in infants. The majority of cases <2 years of age are classed as idiopathic, with viral infection implicated as one of the causes. Coronavirus disease 2019 (COVID-19) public health measures led to significant decreases in communicable disease prevalence. During these times, reductions in intussusception frequency were greater than would be expected with our previous understanding of its infectious etiology. Methods. We conducted a retrospective, multistate, ecological study over a 12-year period. Monthly case numbers of "intussusception"-coded admissions (code K56.1; International Classification of Diseases and Related Health Problems, Tenth Revision, Australian Modification) were acquired from state-wide admissions data sets from New South Wales, Victoria, and Queensland, representing 77.62% of the eligible Australian population. These counts within differing jurisdictional lockdowns were compared with non-lockdown periods in order to investigate a correlation between intussusception frequency and lockdown periods. Results. We found a negative association between intussusception frequency and lockdown periods in both eligible states. The largest reductions were seen in the <2-year age groups, with Victoria experiencing a 62.7% reduction (rate ratio, 0.37; P < .001) and New South Wales a 40.1% reduction (0.599; P = .006) during lockdown times. Controls for variations in lockdown restrictions between both regional and metropolitan areas also showed expected decreases. Conclusions. Our ecological study demonstrates significant decreases in the frequency of pediatric intussusception admissions during the COVID-19 lockdown periods. The unexpected magnitude of the reductions suggests that the true proportion of infectious disease-caused idiopathic intussusception is greatly underestimated.