More Bronchiolitis Hospitalizations Occurred During the Pandemic Period Than the Prepandemic Period, Study Says

This article was originally published by HCPLive^®. It has been lightly edited.

The seasonality of bronchiolitis has not returned to the patterns of the pre-COVID-19 pandemic era (2010-2019), according to a study published in JAMA Network Open.¹

The investigators that identified these findings noted that bronchiolitis cases usually follow a seasonal pattern that is predominant in winter, with its peak occurring from December to February within the Northern Hemisphere and May to July within the Southern Hemisphere. The measures, such as social distancing and masks, were linked with significant reductions in bronchiolitis admissions in the early period of the pandemic.²

To assess pattern changes since the pandemic ended, new research was led by Kailey A. Remien, DO, of the Akron Children’s Hospital. Remien and colleagues worked to assess the changes of COVID-19 pandemic era bronchiolitis admissions compared to those of the pre-pandemic period from 2010 to 2019.¹

“We hypothesized that admissions would be higher than expected, that there would be unusual seasonality, and that patients would be older than those in previous years due to waning herd immunity from lack of exposure,” Remien and colleagues wrote.

Background and Findings

The investigators used a retrospective cross-sectional study design, extracting their data from the Pediatric Health Information System database; this database covers 41 children's hospitals across the US.

The research team noted that bronchiolitis shows its seasonality pattern predominantly during the winter months, so their hospitalization data was categorized based upon bronchiolitis seasons spanning from July to June. The team included all pediatric patients who had been both under 2 years of age and admitted with a bronchiolitis diagnosis within the timeframe of July 2010 to June 2023.

The investigators stratified the bronchiolitis seasons between 2010 and 2011 and 2019 and 2020, with these being labeled as the pre-pandemic period; the 2020 to 2021 and 2022 to 2023 seasons were labeled as the pandemic period.

The research team carried out their analysis of the data from July 2010 to June 2023, with their main focus of the research being to look at the variation in hospitalization numbers for cases of bronchiolitis over different seasons and months.

The team transformed their historical monthly admission data from the pre-pandemic era into time series to achieve their primary goal, and these elements were utilized to formulate forecasting models to help predict monthly admissions in the pandemic period.

Hospitalized pediatric patient

iImage credit: pingpao - stock.adobe.com

Overall, the investigators analyzed a total of 400,801 admissions for bronchiolitis from 349,609 subjects. They found that their study population had a median age of 6 months (IQR, 2-12 months), and it was made up of 58.7% male patients and 43.7% White patients.

They found that hospitalizations had a steady increase during the pre-pandemic time period, noting a median of 29,309 hospitalizations. During the pandemic period, the research team identified a 69.2% reduction of hospitalizations during the 2020 to 2021 season, followed by a 75.3% increase during the 2022 to 2023 season.

The investigators also reported that the subjects who had been admitted in the pandemic period were shown to have been somewhat older vs the subjects seen in the pre-pandemic period, with a median age of 7 months as opposed to 6 months, respectively; this was noted to be a statistically significant difference (P < .001).

They also found an increase in the admissions to intensive care units (ICUs), identifying an increase from 32.2% in the pre-pandemic period to 36.7% in the pandemic period (P < .001). The investigators noted that the seasonality of admissions due to bronchiolitis showed shifts in the pandemic period, demonstrating that peak admissions were found to have happened in August 2021 and November 2022.

The research team found that these occurrences were consistent in their sensitivity analyses that had excluded young patients with complex chronic conditions and repeat admissions. In an additional sensitivity analysis covering all viral lower respiratory tract infections in those aged younger than 5 years, the team found 66,767 admissions were shown in the 2022 to 2023 pandemic period as opposed to 35,623 in the pre-pandemic period.

Overall, the team found the most substantial hospitalization increase in the subjects who were between the ages of 24 to 59 months. While their findings were informative, the team acknowledged some of the potential limitations of their research.

“Because the PHIS is not geographically comprehensive, patient relocation or changes in referral patterns during the study may affect the results,” they wrote. “For example, if community hospitals increased the proportion of children referred to children’s hospitals during the COVID-19 pandemic, it would increase the number of admissions captured in the PHIS.”

References

1. Remien KA, Amarin JZ, Horvat CM, et al. Admissions for Bronchiolitis at Children’s Hospitals Before and During the COVID-19 Pandemic. JAMA Netw Open. 2023;6(10):e2339884. doi:10.1001/jamanetworkopen.2023.39884
2. Pelletier JH, Rakkar J, Au AK, Fuhrman D, Clark RSB, Horvat CM. Trends in US pediatric hospital admissions in 2020 compared with the decade before the COVID-19 pandemic. JAMA Netw Open. 2021;4(2):e2037227. doi:10.1001/jamanetworkopen.2020.37227