Estimating Trends, Quantifying Changes From RSV's Burden on Health Care Systems

Overburdened health care systems, such as during pandemics, can have their changes in respiratory syncytial virus (RSV) quantified and long-term temporal and spatial trends estimated using hospital admissions data, according to a study published in Frontiers in Pediatrics.

RSV most frequently causes mild respiratory tract infections, but can be more severe in children younger than 2 years. RSV infection is best anticipated by the season, being most frequent in the late fall, winter, and early spring. However, the COVID-19 pandemic has altered the seasonality of RSV. This study aimed to quantify how the COVID-19 pandemic has affected pediatric RSV infections at the state and county level in Texas.

Texas hospital discharge records and Texas Public Use Data Files (PUDF) from 2006 quarter 1 to 2021 quarter 4 were used for this study. Discharge diagnoses, length of stay, patient age, patient status at the end of service, and patient county were the variables used. All discharge diagnoses were included in the dataset, and analysis focused on RSV-associated hospitalizations in children 5 years and younger.

Cumulative quarterly hospitalization rates for children 4 years and younger were calculated from the monthly RSV-associated hospitalization rates that were reported from 2018 to 2022 in the RSV Hospitalization Surveillance Network (RSV-NET). Children were separated into 3 groups based on the PUDF datasets: 1 to 28 days old, 29 to 365 days old, and 1 to 4 years old.

There were 158,920 RSV-associated hospitalizations from 2006 to 2021 that were included in this study, with most hospitalizations being seen in children younger than 5 years (89%). Breaking this down further, hospital admissions were at their highest among children aged 29 to 365 days(65%) and at their lowest in those 1 to 28 days old (8%) from 2006 to 2019. However, this switched in 2021, when the highest percentage of hospital admissions were seen for patients aged 1 to 28 days (57%) and 1 to 4 years (40%).

Seasonal patterns in hospital admissions were consistent between 2006 and 2019. The highest numbers of cases were found in 2010, 2011, and 2019, and all years from 2006 to 2019 had a general decreasing trend in cases in Q1 and increased in all other quarters.

Compared with a linear regression model that estimated hospital admissions for RSV in 2020 and 2021 minus the imnpact from COVID-19, a low number of hospitalizations were seen in the 2020 season and an intensified peak was seen in 2021 Q3. The outbreak peak was 1.5 times higher than expected and occurred nearly a year after expected, at 2021 Q3 rather than 2020 Q4. The number of cases in 2021 Q2 (n = 1223) was also 2.6 times higher than a typical season and 5 times higher with an assumed season shift. Rates of hospitalization saw a decreasing trend over time in Q1 whereas all other quarters saw an increasing trend.

RSV-associated hospitalizations were 1.9 and 9.5 times higher on the state and county levels from 2018 to 2021 compared with those reported in the RSV-NET data. The discrepancy was higher in 2020 and 2021, with the mean county level rate 43 times that of RSV-NET and the state hospitalization rate 5 times that reported in RSV-NET.

Length of stay followed seasonal trends from 2006 to 2019, with longer stays in Q2 and Q3. However, this was affected during the pandemic, as length of stay was up to 6.5 times longer than expected in 2020 Q4 (29.3 vs 4.5 days). The rate of expired status was 2.28 times higher in 2020 (0.39%) compared with the 2006 to 2019 average (0.17%).

The highest hospitalization rate in Texas in Q2 2020 was in a rural county, and 3 urban counties reported cases during the pandemic. RSV reemergence was found to follow typical onset but had higher and more broadly distributed rates. No cases of RSV were found in rural areas along the southwest border during the COVID-19 pandemic but were reported prior to 2020 Q2.

Potential limitations on these study findings include that the researchers used International Classification of Diseases, Ninth Revision, and 10th Revision, Clinical Modification codes to diagnose RSV, which could have misrepresented the hospital burden; co-infections and risk factors for RSV hospitalizations were not examined in this study; and lack of viral exposure was not tested as a reason for an atypical peak of RSV in 2021.

The researchers concluded that observing hospitalizations associated with RSV is an important way to evaluate the burden of RSV infections on pediatric hospitals. Observing how the COVID-19 pandemic altered RSV hospital admissions clarifies the role that the pandemic played in the seasonality and extended hospital stays for RSV.

Reference

Uwak I, Johnson N, Mustapha T, et al. Quantifying changes in respiratory syncytial virus—associated hospitalizations among children in Texas during COVID-19 pandemic using records from 2006 to 2021. Front Pediatr. Published online March 13, 2023. Doi:10.3389/fped.2023.1124316