Trends in Lower Respiratory Tract Diagnoses and Nonrecommended Bronchiolitis Therapies

Differentiating bronchiolitis from other lower respiratory tract (LRT) diagnoses is challenging because of shared clinical features. We hypothesized that recently reported decreases in nonrecommended bronchiolitis therapies may be overestimated because of shifts in diagnostic assignment.

We performed a multicenter retrospective cohort study across 40 hospitals from 2010 to 2022 using the Pediatric Health Information Systems database. For children aged younger than 2 years with LRT discharge diagnoses, we analyzed trends in (1) the proportion of encounters with assigned diagnosis of bronchiolitis, asthma (including "reactive airway disease"), and pneumonia and (2) the receipt of bronchodilators, systemic steroids, and/or antibiotics.

We identified 1 023 745 encounters with an LRT diagnosis. The proportion of LRT conditions diagnosed as bronchiolitis increased from 55.4% to 79.6% (adjusted incidence rate ratio [aIRR], 1.022; 95% CI, 1.019-1.026), signifying a relative increase of 2.2% per year, while asthma decreased from 22.1% to 6.1% (aIRR, 0.918; 95% CI, 0.897-0.939), and pneumonia decreased from 12.5% to 4.7% (aIRR, 0.925; 95% CI, 0.913-0.937). Across all LRT diagnoses, bronchodilator and steroid use decreased from 49.5% to 28.6% (aIRR, 0.947; 95% CI, 0.936-0.958) and 23.3% to 18.4% (aIRR, 0.982; 95% CI, 0.972-0.992), respectively. Similarly, antibiotic use declined from 13.9% to 10% (aIRR, 0.975; 95% CI, 0.962-0.989). Revisits with LRT diagnoses were unchanged.

The proportion of LRT conditions identified as bronchiolitis has increased over time, while nonrecommended bronchiolitis therapies have decreased. Further exploration is needed to elucidate this relationship, which suggests a potential influence of therapeutic stewardship on ultimate diagnoses.