key: cord-0839707-lk0idn5q
authors: Succi, Marc D.; Chang, Ken; An, Thomas; Rosman, David A.; Raja, Ali S.; Gee, Michael S.; Lev, Michael H.; Liu, Ray; Saini, Sanjay; Brink, James A.
title: Increased per-patient imaging utilization in an emergency department setting during COVID-19
date: 2021-06-07
journal: Clin Imaging
DOI: 10.1016/j.clinimag.2021.06.003
sha: f7fe144eff6df1b06301d471cc0aad2530b1d75f
doc_id: 839707
cord_uid: lk0idn5q

INTRODUCTION: COVID-19 has resulted in decreases in absolute imaging volumes, however imaging utilization on a per-patient basis has not been reported. Here we compare per-patient imaging utilization, characterized by imaging studies and work relative value units (wRVUs), in an emergency department (ED) during a COVID-19 surge to the same period in 2019. METHODS: This retrospective study included patients presenting to the ED from April 1–May 1, 2020 and 2019. Patients were stratified into three primary subgroups: all patients (n = 9580, n = 5686), patients presenting with respiratory complaints (n = 1373, n = 2193), and patients presenting without respiratory complaints (n = 8207, n = 3493). The primary outcome was imaging studies/patient and wRVU/patient. Secondary analysis was by disposition and COVID status. Comparisons were via the Wilcoxon rank-sum or Chi-squared tests. RESULTS: The total patients, imaging exams, and wRVUs during the 2020 and 2019 periods were 5686 and 9580 (−41%), 6624 and 8765 (−24%), and 4988 and 7818 (−36%), respectively, and the percentage patients receiving any imaging was 67% and 51%, respectively (p < .0001). In 2020 there was a 170% relative increase in patients presenting with respiratory complaints. In 2020, patients without respiratory complaints generated 24% more wRVU/patient (p < .0001) and 33% more studies/patient (p < .0001), highlighted by 38% more CTs/patient. CONCLUSION: We report increased per-patient imaging utilization in an emergency department during COVID-19, particularly in patients without respiratory complaints.

The disruptive effects of the COVID-19 pandemic have caused significant declines in imaging volume in emergency departments. Absolute decreases in imaging volume have ranged between 28-55% across all patient service locations (e.g. inpatient, outpatient, and emergency departments) in recent studies.(1-3) Emergency department (ED) imaging volume has similarly been affected by the pandemic, with absolute imaging volumes decreasing 42% compared to pre-COVID levels. (4) While recent studies on imaging volume in the context of the pandemic have highlighted absolute declines in imaging utilization and corresponding work relative value unit (wRVU) data, specific data on changes in per-patient utilization, including data by modality and corresponding wRVU, have not been reported. (5) (6) (7) (8) Such data may be of benefit to recently published models detailing financial recovery predictions as hospitals aim to resume operations. (6, 9) Lastly, with widespread news of decreased ED imaging volumes and concern that sick patients are avoiding the ED secondary to fear of contracting COVID-19, analyzing imaging utilization on a per-patient basis may support anecdotal reports of the increasing complexity of presenting patientslow-acuity patients who are less likely to be imaged may be avoiding the ED. (10) (11) (12) (13) (14) (15) Subgroups II and III were intended to highlight the primary respiratory-centered presenting complaints of COVID-19 patients, and to quantify this impact by utilization year-over-year.

Distinction between subgroups II and III was based on the chief complaint as recorded by the ED clinician. This field allows for both pre-defined text input and manually entered free-text, and is logged in our EHR and typically recorded upon initial patient presentation to the ED. The vast majority entered are pre-defined text, followed by a mix of pre-defined and free text, and finally less than 1% free text only. The criteria terms for inclusion in subgroup II were: "aspiration", "asphyxia", "asthma", "bronchitis", "chills", "cough", "COVID", "COPD", "crackles", "fever", "hypoxemia" "hypoxia", "nasal congestion", "phlegm", "pleural", "pneumonia", "pulmonary", "pulmonary embolism", "rales", "shortness of breath", "sore throat", "sputum", "stridor", and "wheeze". Upon categorizing the patient in either subgroup II or III or VI and VII, all imaging studies associated with the patient, regardless of body part or modality, were included in the perpatient calculations for these groups. Patient descriptive data, including age and gender, were collected from the EHR. All corresponding imaging exam codes and classes performed in our ED imaging locations were also collected during the study period. To calculate wRVUs, we obtained a list of all exam classes, and manually correlated these to the 2020 National Physician Fee Schedule Relative Value File July Release.(17)

The primary study outcome was per-patient imaging utilization, defined as overall/modalityspecific studies/patient and wRVUs/patient, among the primary subgroups. Modalities analyzed J o u r n a l P r e -p r o o f included computed tomography (CT), ultrasound (US), magnetic resonance imaging (MRI), and conventional radiograph (CR). Per-patient utilization in this context is the number of imaging studies or wRVUs during the study period divided by the total number of presenting patients in each subgroup, regardless of if they received imaging. Using wRVU allows generalizability to practice outside of our geographic location, and further generalizability between facility and nonfacility practices. It is understood that using only the wRVU component of reimbursement likely results in more conservative, but also more generalizable, results. Secondary study outcomes included imaging utilization as previously defined in the secondary subgroups -by disposition and COVID test status.

The number of patients presenting to the ED during the 2020 and 2019 study periods determined the sample size.

Patient demographics were reported via descriptive statistics. If a patient presented to the ED for multiple visits during the study period, each visit was treated as a separate patient encounter. (Table 1) The total number of patients presenting to the ED during the 2020 and 2019 study periods was 5686 and 9580 respectively, an approximate 41% decrease for 2020. All patients presenting to the ED were included. The total number of imaging exams during the 2020 and 2019 study periods was 6624 and 8765, an approximate 24% decrease for 2020. "other" category, again reflecting ED disposition, includes patients transferred, direct-admits, those sent directly to the operating room, patient demise, or for whom the information was not available (failure of documentation).

To examine the data in a granular manner beyond absolute volume and wRVU changes, we examined mean per-patient imaging utilization ( or US utilizationthis may be in part be due to the relatively low use of these modalities in the ED compared to CT and CR ( Supplementary Tables 1 and 2 ).

In 2020 there was a 7% increase in studies/patient (studies/patient 2020 vs Table 2 ).

There was no significant difference in imaging utilization when analyzing 2020 COVID+ patients presenting with respiratory complaints and non-COVID+ patients presenting with respiratory complaints, as shown in 

To our knowledge this is the first report of increased per-patient imaging utilization during the COVID-19 pandemic. Analyzing emergency department patients presenting without respiratory complaints minimizes confounding by pulmonary-centric COVID-19 presentations: in this subgroup we observed a significant 33% increase in imaging studies/patient and 24% increase in wRVU/patient, compared to 2019, including a 38% increase in CTs/patient. Notably, we observed a significant 170% relative increase in patients presenting with respiratory complaints, accounting for 38.6% of all patients in 2020, compared to 14.9% in 2019. As respiratory patients carry just 53% of the average wRVU/patient of a non-respiratory patient, this engenders a double-financial hit to emergency departments and associated imaging operations -absolute volume contraction and increased lower-wRVU patient profiles.

The absolute decline (-24%) in total imaging exams during the 2020 study period compared to Despite absolute imaging volume contraction, in the 2020 study period there was, across the board, a 7% increase in wRVU/patient and corresponding 27% increase in studies/patient, compared to the same period in 2019. When analyzing non-respiratory presenting patients, these numbers are even more pronounced -24% and 33% increases in wRVU/patient and studies/patient, respectively. The overall tempered wRVU increase in the context of the 27% overall imaging utilization increase for all patients in 2020 is consistent with the lower average wRVU for respiratory patients (53% of the average wRVU for non-respiratory patients in 2020, and 62% in 2019), which accounted for a 170% relative increase (60% absolute) in ED visits compared to 2019 (38.6% vs. 14.3%). This double financial hit, comprised of (I) absolute volume contraction and (II) increased proportion of lower-value wRVU volume, is significant and can be taken into account by financial managers at all practicesfor forecasting quarterly revenue or preparing for additional surges of this or other pandemics.

In general, causes for the observed increase in per-patient imaging utilization are likely multifactorial. Clinical uncertainty in the diagnosis and management of COVID-19 may have spurred increased diagnostic testing by clinicians regardless of presenting complaint, thereby leading to increased imaging. Further, as many patients began to avoid the healthcare system to reduce risk of exposure to COVID-19, the average acuity of patients presenting to the ED may have increased. (10, 19) This difference in acuity is suggested by the significant increase in the proportion of patients in the ED that were admitted in 2020 compared to 2019 (42% vs. 25%, respectively), and may be proxied by increased imagingwe observed a significant increase in patients receiving any imaging (67% vs. 51%, respectively).

Limitations Regarding imaging utilization in the ED of COVID+ compared to non-COVID+ patients presenting with respiratory complaints, we found no difference in imaging studies/patient or wRVU/patient. However this secondary analysis has significant limitations as (I) our data was ED-specific, excluding inpatient imaging and (II) our data was collected in aggregate, therefore the COVID+ group could theoretically have included patients with a positive test prior to the ED, patients tested and resulted while in the ED, and patients tested and resulted after ED discharge.

Among all data, the retrospective and aggregate data collection limited assessment for the precise causes for the changes in imaging volume. Geographic and temporal variability in the effects of COVID-19 throughout the United States may limit the ability to extrapolate the results of this study to other radiology practices. Our study period is one-month during the first-wave of COVID, and therefore does not assess longitudinal practice patterns during subsequent waves of the pandemic. Lastly, our study is at a large academic center, and primarily generalizable to similar practices reading ED imaging.

In conclusion, this study is the first to report increased per-patient imaging utilization during COVID-19, characterized by significantly increased studies and wRVUs. We also identified a significantly increased proportion of patients receiving imaging as well as increased admitted patients, suggesting that less-acute patients are avoiding care. As the effects of COVID-19 on radiology practices continue to evolve, knowledge of individualized utilization growth metrics may help departments understand and plan for imaging trends. J o u r n a l P r e -p r o o f J o u r n a l P r e -p r o o f 

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