Regional racial differences in mortality after bronchiolitis: a nationally representative study

Introduction: Bronchiolitis is common in infants and young children, accounting for 15-17% of overall pediatric hospitalizations with a wide range of outcomes. We sought to assess whether there exist disparities in outcome by race after hospitalization for bronchiolitis using a nationally representative sample. Methods: We performed retrospective cohort study using data from 2016 and 2019 Healthcare Cost and Utilization Project Kids’ Inpatient Database (KID). In unadjusted and adjusted models, we tested the association between race/ethnicity (White, Black, Hispanic, Other) and mortality. Directed acyclic graphs identified patient- (age, gender, complex chronic condition, insurance payer, median household income) and hospital-level (size, region, teaching status, ownership) confounders. Geographic region was a priori treated as an effect modifier. We used population-weighted mixed effects logistic regression with hospital as a random effect. We powered the study to detect an odds ratio of 1.2 for Black compared to White mortality, using an expected mortality of 0.5%, necessitating sample size of 173,706. Results: 195,951 eligible children had complete race and outcome data for analysis. The median length of stay was 3 (IQR 2-4) and overall mortality was 0.14% (n=265). In both univariable and multivariable models, Black race had higher mortality odds compared to White (OR=1.37, CI 0.97-1.94, p=0.072; adjusted OR=1.16, CI 0.82-1.64, p=0.395), but neither reached statistical significance. In the pre-specified analysis by geographic region, Black race was associated with higher mortality in the South (aOR=1.95, CI 1.12-3.18, p=0.007), but not in the Northeast, Midwest, or West. Conclusions: In this large, nationally representative cohort, we found a lower mortality for bronchiolitis than previously reported. Overall, Black race had higher odds of mortality, but we were underpowered to detect a significant mortality difference. After stratification by region, we found Black children had higher odds of mortality compared to White children in the South, consistent with previous literature in sepsis and confirming the importance of regional assessments in studies of disparities in the United States. Further studies are necessary to elucidate the contributing factors to this racial disparity.