Rates in Bronchiolitis Hospitalization, Intensive Care Unit Use, Mortality, and Costs From 2004 to 2018.

Importance: Over the last 2 decades, bronchiolitis guidelines and improvement efforts focused on supportive care and reducing unnecessary tests, treatments, and hospitalization. There have been limited population-based studies examining hospitalization outcomes over time.

Objective: To describe rates and trends in bronchiolitis hospitalization, intensive care unit (ICU) use, mortality, and costs.

Design, Setting, And Participants: This cohort study used population-based health administrative data from April 1, 2004, to March 31, 2018, to identify bronchiolitis encounters using hospital discharge diagnosis codes in Ontario, Canada. Children younger than 2 years with and without bronchiolitis hospitalization were included. Data were analyzed from January 2020 to July 2021.

Main Outcomes And Measures: Bronchiolitis hospitalization per 1000 person-years, ICU use per 1000 hospitalizations, mortality per 100 000 person-years, and costs per 1000 person-years adjusted to 2018 Canadian dollars and reported in 2018 US dollars.

Results: Among 2 336 446 included children, 1 199 173 (51.3%) were male. During the study period, 43 993 children (1.9%) younger than 2 years had 48 058 bronchiolitis hospitalizations at 141 hospitals. Bronchiolitis accounted for 48 058 of 360 920 all-cause hospitalizations (13.3%) and 215 654 of 2 566 348 all-cause hospital days (8.4%) in children younger than 2 years. Bronchiolitis hospitalization was stable over time, at 14.0 (95% CI, 13.6-14.4) hospitalizations per 1000 person-years in 2004-2005 and 12.7 (95% CI, 12.2-13.1) hospitalizations per 1000 person-years in 2017-2018 (annual percent change [APC], 0%; 95% CI, -1.6 to 1.6; P = .97). ICU admission increased significantly from 38.1 (95% CI, 32.2-44.8) per 1000 hospitalizations in 2004-2005 to 87.8 (95% CI, 78.3-98.0) per 1000 hospitalizations in 2017-2018 (APC, 7.2%; 95% CI, 5.4-8.9; P < .001). Over the study period, bronchiolitis mortality was 2.8 (95% CI, 2.3-3.4) per 100 000 person-years and remained stable (APC, 1.1%; 95% CI, -8.4 to 11.7; P = .85). Hospitalization costs per 1000 person-years increased from $49 640 (95% CI, $49 617-$49 663) in 2004-2005 to $58 632 (95% CI, $58 608-$58 657) in 2017-2018 (APC, 3.0%; 95% CI, 1.3-4.8; P = .002).

Conclusions And Relevance: From 2004 to 2018, bronchiolitis hospitalization and mortality rates remained stable; however, ICU use and costs increased substantially. This represents a major increase in high-intensity hospital care and costs for one of the most common and cumulatively expensive conditions in pediatric hospital care.