Results
In the three years prior to the pandemic, there were over 2000 ED visits
for bronchiolitis per year, averaging 3.1% of all visits seen (Table
1). In 2020, there were 450 visits for bronchiolitis, representing 1%
of all ED visits, a statistically significant decrease in mean
bronchiolitis visits over the 5 years of study, (F = 4.5, p=0.003). All
years had higher mean bronchiolitis visits compared to 2020, Tukey’s HSD
for year to year comparisons, (alpha=0.05),|2017 vs
2020|=146.4167 (p=0.0358); |2018 vs
2020|=149.75 (p=0.03); |2019 vs
2020|=157.6667 (p=0.0196); |2020 vs
2021|=191.0833 (p=0.0027). In the second year of the pandemic
(2021), bronchiolitis visits had the highest proportion of ED visits for
the 5 study years at 4% in addition to having the highest number of
visits (2743 visits). Race/ethnicity, gender and age were similar
between study years. There was an increase in rates of patients with
bronchiolitis admitted to the hospital in the first year of the pandemic
at 44% but returned to previous rate of 38% the following year. Viral
testing was performed on 11% of patients on average, which increased to
35% during the pandemic but again decreased the year after. In the
pre-pandemic period (2017-2019), RSV was positive in 43% of samples
versus 29% in the pandemic period (2020-2021) (z=4.9,
p<0.0001). In 2020 alone only 4% of viral testing was
positive for RSV, followed by a sharp rebound to 63% in 2021-2022
(Table 1 and Figure 2). Rhino/enterovirus was detected in 92% of viral
samples in 2020 (Table 1 and Figure 1). While there were no patients
diagnosed with bronchiolitis with COVID-19 through the first year of the
pandemic, 31% tested positive in the second year (Table 1 and Figure
1).
Multiple measures were analyzed to assess acuity of visits including
estimated severity index (ESI), admission unit and use of high flow.
There was no difference in ESI scores pre-pandemic compared to pandemic;
median ESI’s were 3 for all study years except for 2018 with median ESI
of 4 (Table 1). During 2020, 22% of patients with bronchiolitis were
admitted to the ICU, which represented a significant increase
(p<0.05) compared to all other study years (Table 2). In the
second year of the pandemic, only 9% of patients were admitted to the
ICU. There was a statistically significant increase (p<0.05)
in high flow usage in 2020 with 23% of patients being placed on high
flow. Chest radiographs increased in the first year of the pandemic
compared to the other study years with 37% compared to 24%-31% in
other years. Albuterol use in 2020 was 29%, compared to 15% in 2021
and 20% and 24% in the 2 years prior to the pandemic.
In addition to changes in overall yearly visit numbers, there was a
shift in the seasonality of visits (Figure 2). Higher numbers of
bronchiolitis visits were seen in late fall and winter in the
pre-pandemic years. During the first year of the pandemic, there was a
uniform decrease in visits for bronchiolitis, with the exception of
March 2020. In 2021, there is a spike in bronchiolitis in the summer
months of June and July with almost 500 visits each month and lower
numbers during the winter months.