LAUSR

Inpatient bronchiolitis outcomes in North America have changed substantially during the past 4 decades. Annual deaths associated with bronchiolitis in the United States were once estimated as high as 4500 in the 1980s,1 with subsequent estimates revising this figure to 510 annual deaths between 1979 and 1997, then 56 to 121 annual deaths by the late 2000s.2 Although a 100-fold reduction in mortality could be construed as emblematic of medical advances, changes in coding practices and epidemiologic disease definitions likely play a larger role in this evolution. Willer et al3 highlight more examples of how diagnostic coding strategies and associated research definitions continue to be associated with surveys of the bronchiolitis landscape. As pediatric mortality has decreased in the developed world, research focus has shifted to improving care efficiency. In line with this trend, Willer et al3 examined resource use for bronchiolitis hospitalizations during the past decade using a high-quality multicenter database, the Pediatric Health Information System (PHIS). They found increasing inflation-adjusted standardized unit costs per hospitalization during the study period without any significant changes in mortality or length of stay. As in previously published studies,4 they found a corresponding increase in intensive care unit (ICU) admissions and a surge in the proportion of children receiving noninvasive ventilation, despite stable use of invasive mechanical ventilation. The authors posit that the observed trends may be driven by an increase in the use of high-flow nasal cannula (HFNC) therapy, which is commonly either initiated or managed in ICUs. Citing a lack of established, objective criteria for initiating HFNC therapy, the authors question whether the subjective assessments of respiratory distress that lead to the use of HFNC therapy may be more indicative of “physician behavior” than patient condition. Characterizing disease patterns in administrative data provides an essential vantage of how care is delivered over time. Our understanding of bronchiolitis epidemiology has improved with the increasing availability and accumulation of large, multicenter, administrative databases containing patient-level data. For example, using consistent methods leveraging the PHIS database, mortality associated with bronchiolitis has been observed to decrease from 14 per 10 000 admissions in 20022003 to 4 per 10 000 admissions in 2011 in the United States, suggesting improvements in care over time and providing important context for the present work.5 Interpreted one way, the stable survival rate of 99.9% between 2010 and 2019 noted by Willer et al3 represents a lack of significant improvement. However, few clinicians would argue that the goal of HFNC therapy is to further reduce mortality in bronchiolitis. Similarly, to our knowledge, there has never been evidence that HFNC therapy reduced the duration of bronchiolitis; it is considered a supportive treatment. For children with bronchiolitis, HFNC therapy can help maintain functional residual capacity with positive airway pressure, facilitate breathing by overcoming nasopharyngeal resistance due to edema and secretions, and wash out physiologic dead space.6 It is by these mechanisms that HFNC therapy is thought to possibly reduce the need for mechanical ventilation. Among children with respiratory distress not requiring invasive ventilation, it is likely that HFNC therapy helps to reduce the work of breathing and improve patient comfort. However, to our knowledge, there are no wellestablished objective respiratory distress scales for bronchiolitis, nor do administrative databases harbor the necessary vital sign data and respiratory assessments to conduct such analyses. Therefore, it is unlikely that databases such as PHIS, which contains no data on vital signs or work of + Related article