key: cord-0937382-peu6lo3e
authors: Schwertner, Adam; McMenamy, John; Naeger, David M.
title: Radiology Imaging Volume Changes During Discrete COVID-19 Pandemic Waves: Implications for the Delta Variant of Coronavirus and Future Pandemics
date: 2021-11-23
journal: J Am Coll Radiol
DOI: 10.1016/j.jacr.2021.09.045
sha: c3e718b79c4b0002abad7ed3d1e68c433f194583
doc_id: 937382
cord_uid: peu6lo3e

PURPOSE: The aim of this study was to evaluate radiology imaging volumes at distinct time periods throughout the coronavirus disease 2019 (COVID-19) pandemic as a function of regional COVID-19 hospitalizations. METHODS: Radiology imaging volumes and statewide COVID-19 hospitalizations were collected, and four 28-day time periods throughout the COVID-19 pandemic of 2020 were analyzed: pre-COVID-19 in January, the "first wave" of COVID-19 hospitalizations in April, the "recovery" time period in the summer of 2020 with a relative nadir of COVID-19 hospitalizations, and the "third wave" of COVID-19 hospitalizations in November. Imaging studies were categorized as inpatient, outpatient, or emergency department on the basis of patient location at the time of acquisition. A Mann-Whitney U test was performed to compare daily imaging volumes during each discrete 28-day time period. RESULTS: Imaging volumes overall during the first wave of COVID-19 infections were 55% (11,098/20,011; P < .001) of pre-COVID-19 imaging volumes. Overall imaging volumes returned during the recovery time period to 99% (19,915/20,011; P = .725), and third-wave imaging volumes compared with the pre-COVID-19 period were significantly lower in the emergency department at 88.8% (7,951/8,955; P < .001), significantly higher for outpatients at 115.7% (8,818/7,621; P = .008), not significantly different for inpatients at 106% (3,650/3,435; P = .053), and overall unchanged when aggregated together at 102% (20,419/20,011; P = .629). CONCLUSIONS: Medical imaging rebounded after the first wave of COVID-19 hospitalizations, with relative stability of utilization over the ensuing phases of the pandemic. As widespread COVID-19 vaccination continues to occur, future surges in COVID-19 hospitalizations will likely have a negligible impact on imaging utilization.

Coronavirus Disease 2019 (COVID-19) has had a major impact on health care system operations throughout 2020 1 . At the beginning of the COVID-19 pandemic, (i.e. "First Wave") institutions restricted the number of imaging studies performed in an attempt to preserve personal protective equipment (PPE), contribute to social distancing, and slow the spread of the disease.

Studies have shown that imaging volumes were significantly reduced in March and April of 2020, particularly outpatient imaging which fell 68% in one single institution retrospective analysis 2 . Similarly, inpatient imaging was seen to decline with a trend towards increased use of radiography versus cross sectional imaging in the early stages of the pandemic 3 .

Health care systems' safety protocols have adapted throughout the COVID-19 pandemic to ensure social distancing while maintaining access to necessary medical care, including medical imaging. Studies comparing actual imaging volumes to estimated models of recovery during the summer of 2020 suggest that medical imaging had made a swift recovery to near Pre-COVID-19 levels 4 . What remains uncertain is how medical imaging volumes changed as subsequent COVID-19 case surges occurred (e.g. Second and Third Waves). In late October and in the latter half of 2021 6 . At the time of writing, this strain is leading to waves of infections, even amongst vaccinated persons 7 . Should our data show substantial delaying of care during multiple waves, cumulative amount of imaging and medical care being deferred may also have implications for the volume of services needed once the majority of the population is vaccinated.

This study aims to evaluate our institution's imaging volumes during discrete surges of COVID-19 hospitalizations. The temporal volume of multiple types of medical imaging was evaluated including inpatient exams, outpatient exams, emergency exams, as well as targeted modality specific exams. We hypothesize that the institution of safety protocols and the general public's increasing familiarity with safety protocols resulted in less drop off in imaging volumes during later surges in the fall of 2020 as compared to the initial surge.

Setting and Data Collection Institutional review board approval was obtained for this study. Our institution is a 525 bed, public hospital and level I trauma center in a centrally located urban setting with a large catchment area. All imaging studies performed at our institution were recorded and Utilizing the data on COVID-19 hospital admissions, four distinct 28-day time periods were selected from the 11-month time span to act as equal sized, representative periods of time during the COVID-19 pandemic based on regional COVID-19 hospitalizations. The four, 28-day time periods are characterized as: Pre-COVID-19, First Wave, "Recovery", and Third Wave.

Colorado did not experience significant case increases during a broad "Second Wave" of summer, 2020. Though the 2020 summer period was indeed not a durable "Recovery", the terminology was ubiquitously used to describe the period with a drop off of cases, so we have used it here as well. The Pre-COVID-19, 28-day time period was selected as January 6, 2020, to 10 . DVT ultrasounds were selected for the analysis of hypercoagulability as this exam was felt to most directly reflect a referring physicians concern for patient hypercoagulability. When comparing daily imaging volumes between 28-day time periods, a Mann-Whitney U test was performed as the data is non-parametric with significant variance from the normal distribution. The Mann-Whitney U test allows for comparison between daily imaging volumes in 1, 28-day time period to that of another 28-day time period.

The deviation of the data from the normal distribution was most pronounced in the outpatient setting with a significant decrease in studies performed during weekends and any included holidays. Each of the four, 28-day time periods contained one United States holiday occurring on a weekday. Statistical analysis was performed with SPSS Statistics by IBM (Armonk, New York.) Statistical significance was defined as a p-value less than 0.05.

Imaging volumes at our institution during the First Wave of COVID-19 infections were 55% J o u r n a l P r e -p r o o f

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