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8 Address: Department of Emergency Medicine, Soonchunhyang University Bucheon Hospital, 170, Jomaru-ro, Bucheon-si, Gyeonggi-do, 1899–5700, Republic of Korea
Sang Soo Han
Footnotes
8 Address: Department of Emergency Medicine, Soonchunhyang University Bucheon Hospital, 170, Jomaru-ro, Bucheon-si, Gyeonggi-do, 1899–5700, Republic of Korea
Affiliations
Department of Emergency Medicine, Soonchunhyang University Bucheon Hospital, Bucheon, South Korea
1 Address: Emergency medicine, Chung-Ang University Hospital, 102, Heukseok-ro, Dongjak-gu, Seoul 06973, Republic of Korea 2 Address: Emergency Medicine, Gwangmyeong Hospital, 110 Deokan-ro, Gwangmyeong-si, Gyeonggi-do 14353, South Korea 3 Address: Emergency medicine, Ewha Womans University Seoul Hospital, 260, Gonghang-daero, Gangseo-gu, Seoul, 07804, Republic of Korea 4 Address: Emergency medicine, Dongtan Sacred Heart Hospital, 7, Keunjaebong-gil, Hwaseong-si, Gyeonggi-do, 18450, Republic of Korea 5 Address: Emergency medicine, 68, Hangeulbiseok-ro, Nowon-gu, Seoul, 01830, Republic of Korea 6 Address: Emergency medicine, 16, Yatap-ro 65beon-gil, Bundang-gu, Seongnam-si, Gyeonggi-do, 13496, Republic of Korea 7 Address: Emergency medicine, 222 Banpo-daero, Seocho-Gu, Seoul 137–701, Seoul, Korea 8 Address: Department of Emergency Medicine, Soonchunhyang University Bucheon Hospital, 170, Jomaru-ro, Bucheon-si, Gyeonggi-do, 1899–5700, Republic of Korea 9 Address: Emergency Medicine, Ewha Womans University Medical Center, 1071, Anyangcheon-ro, Yangcheon-gu, Seoul, 07985, Korea
This study presents the impact of COVID-19 on revisits to the emergency department comparing revisit rates and characteristics between the pre-COVID-19 and COVID-19 periods.
Methods
This multi-center retrospective study included patients over 18 years of age who visited emergency departments during the pre-COVID-19 period and the COVID-19 pandemic. The revisit rates were analyzed according to five age groups; 18–34, 35–49, 50–64, 65–79, and ≥ 80 years, and three revisit time intervals; 3, 9, and 30 days. Also, we compared the diagnosis and disposition at revisit between the study periods.
Results
The revisit rates increased with age in both study periods and the revisit rates among all age groups were higher in the COVID-19 period. The proportion of infectious and respiratory diseases decreased during the COVID-19 period. The ICU admission rate and mortality at the revisit among patients aged ≥ 80 years were lower in the COVID-19 period than in the pre-COVID-19 period.
Conclusion
The revisit rates increased with age in both study periods and there were several changes in the diagnosis and disposition at the revisit in the COVID-19 period.
The worldwide COVID-19 pandemic has changed the emergency medical system. Many patients did not visit the emergency department (ED) because of a fear of infection; therefore, the total number of patients visiting the ED sharply decreased during the COVID-19 period globally [
Trends in emergency department visits and hospital admissions in health care systems in 5 states in the first months of the COVID-19 Pandemic in the US.
]. Furthermore, the number of patients with respiratory disease, infectious diseases, and trauma significantly decreased because of personal protective equipment and social distancing [
]. The clinical process in the emergency department also changed. For example, patients with suspected COVID-19 infection had to use isolation rooms, and physicians had to wear personal protective equipment to prevent the spread of COVID-19 infection in South Korea [
Comparative evaluation of the prognosis of septic shock patients from before to after the onset of the COVID-19 pandemic: a retrospective single-center clinical analysis.
]. These changes might also have impacted the ED revisit.
The ED revisit is important because it relates to emergency care quality, indicating that initial ED evaluation, treatment, and discharge education are inadequate [
]. Thus, it is important to minimize unnecessary ED revisits. However, there are few studies on ED revisits during the COVID-19 period. Although Alwood et al. conducted a study on ED revisits during the COVID-19 period, it did not apply to the general public because it included only frequent ED users who visited the ED more than four times a year [
]. Therefore, we aim to identify ED revisit rates and characteristics of ED revisits in the COVID-19 period by comparing them with those in the pre-COVID-19 period.
Methods
Study design and setting
We conducted a retrospective observational study on ED visits of patients aged ≥ 18 years in seven tertiary university hospitals during the COVID-19 pandemic (1 March 2020–31 March 2021), compared to the same time period in the pre-COVID-19 period (1 March 2018–31 March 2019). The seven hospitals included in this study were located in metropolitan, South Korea, and the annual average number of patients who visit the ED of these hospitals ranged from 36,000 to 70,000 in the pre-COVID-19 period.
Identification of index visit and revisit
All patients older than 18 years who visited the ED in the study period were included in this study. We excluded patients who visited the ED for non-medical or unknown reasons and patients who visited the ED more than five times a year because these frequent ED users have different characteristics from non-frequent ED users [
]. Next, we excluded all visits from 1 to 31 March 2019 in the pre-COVID-19 period and from 1 to 31 March 2021 in the COVID-19 period because we could not identify whether there would be revisits for these visits in the next 30 days during the study periods. The visits during this period were only used to assess revisits. The visits where the patients left against medical advice, died in the ED, were admitted from ED, transferred to another facility, or whose disposition was unknown were also excluded because these visits had no possibility of revisits. All remaining revisits were defined as index visits; among these, only visits for medical reasons were defined as a revisit. The index visit is the first visit of two consecutive ED visits, and the immediately following visit is a revisit. Therefore, the revisit could be the index visit of the subsequent revisit, and a patient could have multiple index visits and revisits.
Measurement of revisit rates
A revisit rate was calculated as the ratio of revisit to index visit. We analyzed the revisit rate stratified by age and time interval from index visit to revisit. The patients were divided into the following five age groups: 18–34, 35–49, 50–64, 65–79, and more than 80 years of age. We set the time intervals for determining a revisit as 3, 9, and 30 days. Although, most studies on ED revisits used the time interval of 3 days [
]. A recent study suggested that revisits within 9 days from an index visit are more reasonable for ED revisits because this cutoff best represents acute ED revisits associated with the index visits [
]. The 30-day time interval was also used for analysis because this timeframe is the standard for assessing hospital quality.
Data collection and outcome measurement
We obtained the data from the National Emergency Department Information System (NEDIS) database, a national database system that transmits and analyzes the information of patients visiting the ED in real-time. The data used for analysis were age, sex, Korea Triage and Acuity Scale (KTAS, Level I, resuscitation; Level II, emergency; Level III, urgent; Level IV, less urgent; and Level V, nonurgent), method of arrival to the ED, vital signs at presentation, diagnosis, and time variables (visit, discharge, and admission), and disposition (discharge, admission, transfer, and death). Unfortunately, we could not link index visits and revisits by diagnosis for this analysis because we only used the data from the NEDIS database and did not analyze medical records. To overcome this as much as possible, we only included patients who visited the ED for medical reasons except for trauma.
The primary outcome was the ED revisit rate within 3, 9, and 30 days stratified by five age groups during pre-COVID-19 and COVID-19 periods. The secondary outcomes compared the final diagnosis and disposition at revisit between pre-COVID-19 and COVID-19 periods. The final diagnosis of revisits was classified according to the International Statistical Classification of Diseases and Related Health Problems − 10 (ICD −10).
Statistical analysis
We conducted all statistical analyses using SPSS (IBM, USA, version 26.0). Categorical variables were presented as percentages, and continuous variables were presented as the mean with standard deviation if they were normally distributed or as the median with interquartile range if they were not normally distributed. To compare the distribution of characteristics between patients of index visits and revisits, we used the chi-squared test for categorical variables and analysis of variance for continuous variables. P-value＜0.05 was considered statistically significant.
Ethical consideration
This study was approved by the institutional review boards (IRB No. 2111–067–19396). The study involved a retrospective review of the hospital database, and all patients were anonymized before the study; therefore, the institutional review boards waived the requirement for informed consent.
Results
The revisit rate in pre-COVID-19 and COVID-19 periods
The total number of ED visits was 464,692 in the pre-COVID-19 period and 317,256 in the COVID-19 period, and there was a decrease of 31.7% in the total number of ED visits in the COVID-19 period. After excluding the visits according to exclusion criteria, the remaining visits of 146,035 in the pre-COVID-19 period and 107,400 in the COVID-19 period were finally determined as index visits, respectively. Among these index visits, only revisits within 30 days for medical reasons were included in the analysis. In the pre-COVID-19 period, there were 6207 (2.8%), 8700 (6.0%), and 12,201 (8.4%) revisits within 3, 9, and 30 days, respectively (Fig. 1A), and in the COVID-19 period, there were 5103 (4.8%), 7010 (6.5%), and 9740 (9.1%) revisits within 3, 9, and 30 days, respectively (Fig. 1B).
Fig. 1A. Flow chart of patients enrolled in the study in the pre-COVID-19 period. B. Flow chart of patients enrolled in the study in the COVID-19 period.
The revisit rates within 3, 9, and 30 days increased with age in both study periods (Fig. 2). In particular, the revisit rates within 3, 9, and 30 days among those over 80 years were 5.5%, 8.7%, and 13.4% in the pre-COVID-19 period and 6.0%, 9.5%, and 14.1% in the COVID-19 period, which significantly increased as the revisit time interval increased, compared with the revisit rates among those aged 18–34 years, which were 3.7%, 4.8%, and 6.7% in the pre-COVID-19 period and 4.1%, 5.2%, and 6.9% in the COVID-19 period. Furthermore, the revisit rates in the COVID-19 period were statistically higher than that in the pre-COVID-19 period among all age groups and all time intervals (p < 0.05), except for those aged 18–34 years within 30 days (p = 0.152) and those aged more than 80 years for all the time intervals (within 3 days, p = 0.282, within 9 days, p = 0.104, within 30 days, p = 0.193) (Table 1).
Fig. 2Revisit rates within 3, 9, and 30 days based on the five age groups.
The average age of patients at revisits was higher than that at index visits in both study periods (47.51 ± 18.46 years vs. 51.73 ± 19.25 years in the pre-COVID-19 period, p < 0.001; 48.30 ± 18.81 years vs. 52.92 ± 19.35 years in the COVID-19 period, p < 0.001). The proportion of KTAS level 1, 2, and 3 for revisits were higher than that for index visits in both the study periods (KTAS 1, 2, and 3 at index visits, 0.2%, 4.3%, and 52.8% and revisits, 0.8%, 4.7%, and 53.0%, respectively in the pre-COVID-19 period, p < 0.001; KTAS 1, 2, and 3 at index visits, 0.1%, 4.8%, and 53.4% and revisits, 0.5%, 5.4%, and 57.8%, respectively in the COVID-19 period, p < 0.001). The mean ED LOS was longer at revisit than at index visit in both study periods (167 ± 393 min vs. 255 ± 386 min in the pre-COVID-19 period, p < 0.001; 163 ± 192 min vs. 259 ± 396 min in the COVID-19 period, p < 0.001) (Table 2).
Table 2Baseline characteristics of the index visit and 30-day revisit in pre-COVID-19 and COVID-19 periods.
Pre-COVID-19 period
COVID-19 period
Index visits (n = 146,035)
30-day revisits (n = 12,201)
p-value
Index visits (n = 107,400)
30-day revisits (n = 9740)
p-value
Age (years), mean± SD
47.51 ± 18.46
51.73 ± 19.25
< 0.001
48.30 ± 18.81
52.92 ± 19.35
< 0.001
Triage level (KTAS, %)
< 0.001
< 0.001
level 1
255 (0.2)
96 (0.8)
136 (0.1)
49 (0.5)
level 2
6335 (4.3)
578 (4.7)
5157 (4.8)
524 (5.4)
level 3
77037 (52.8)
6464 (53.0)
57401 (53.4)
5633 (57.8)
level 4
49962 (34.2)
3717 (30.5)
34046 (31.7)
2513 (25.8)
level 5
12427 (8.5)
1337 (11.0)
10649 (9.9)
1018 (10.5)
Transportation to the hospital (%)
0.365
0.603
Self-presentation
118569 (81.2)
9865 (80.9)
85551 (79.7)
7737 (79.4)
Ambulance
27462 (18.8)
2335 (19.1)
21848 (20.3)
2003 (20.6)
Vital signs at presentation, mean± SD
SBP (mmHg)
133.66 ± 22.01
131.76 ± 22.71
< 0.001
137.68 ± 23.29
135.09 ± 23.62
< 0.001
DBP (mmHg)
79.89 ± 13.69
78.81 ± 14.38
< 0.001
81.40 ± 14.42
79.78 ± 14.92
< 0.001
MAP (mmHg)
97.81 ± 15.04
96.45 ± 15.78
< 0.001
100.15 ± 15.81
98.22 ± 16.17
< 0.001
PR (times/min)
86.00 ± 16.79
87.74 ± 17.63
< 0.001
85.87 ± 16.86
87.80 ± 17.30
< 0.001
RR (time/min)
19.34 ± 2.18
19.42 ± 2.42
< 0.001
19.28 ± 2.35
19.42 ± 3.13
< 0.001
BT (◦C)
36.85 ± 0.74
36.91 ± 0.77
< 0.001
36.37 ± 2.07
36.65 ± 2.93
0.042
Median ED LOS (min), mean± SD
167 ± 393
255 ± 386
< 0.001
163 ± 192
259 ± 396
< 0.001
Abbreviations: KTAS, Korea Triage and Acuity Scale; SBP, systolic blood pressure; DBP, diastolic blood pressure; MAP, mean arterial pressure; PR, pulse rate; RR, respiratory rate; BP, body temperature; ED, Emergency Department; LOS, length of stay.
There were several changes in the top five discharge diagnoses at revisit between the pre-COVID-19 and COVID-19 periods (Table 3). The infectious and parasitic diseases fell among patients aged 18–34 years within 3 days revisit, 35–49 years within 3 days revisit, 50–64 years within 30 days revisit, and 65–79 years within 9 days revisit in the COVID-19 period. The ranking of respiratory diseases dropped among all age groups within all revisit time intervals, except for patients aged 35–49 years within 3 and 9 days of revisit in the COVID-19 period. In particular, among those aged more than 80 years, the ranking fell sharply within all revisit time intervals. Furthermore, the circulatory diseases newly ranked fifth, fifth, and fourth among patients aged 35–49 years within 3, 9, and 30 days revisit, respectively, and fourth among patients aged 50–64 years within 30 days revisit, aged 65–79 years within 9 days revisit, and aged more than 80 years within 3 days revisit in the COVID-19 period.
Table 3Top five discharge diagnoses at revisit within 3, 9, and 30 days of the first visit emergency department distributed by age. (A) Pre-COVID-19 period, (B) COVID-19 period.
In all age groups within all revisit time intervals, the rate of ED discharge decreased, and the rate of ICU admission and mortality increased with age in both pre-COVID-19 and COVID-19 periods (Table 4). Comparing pre-COVID-19 and COVID-19 periods, the rate of ICU admission was higher in the COVID-19 period than in the pre-COVID-19 period within all revisit time intervals, except for patients more than 80 years of age (pre-COVID-19 period vs. COVID-19 period within 3 days revisit, 7.6% vs. 4.7%; within 9 days revisit, 6.5% vs. 4.8%; within 30 days revisit, 6.8% vs. 5.4%). The rate of mortality was lower in the COVID-19 period than in the pre-COVID-19 period among patients aged 65–79 years and patients aged more than 80 years within all revisit time intervals (pre-COVID-19 period vs. COVID-19 period within 3 days revisit, 0.3% and 1.1% vs. 0.1% and 0.7%; within 9 days revisit, 0.4% and 1.3% vs. 0.2% and 0.8%; within 30 days revisit, 0.4% and 1.4% vs. 0.2% and 1.1%).
Table 4Disposition at the 3-, 9-, and 30-days emergency department revisits. (A) Pre-COVID-19 period, (B) COVID-19 period.
To the best of our knowledge, this is the first report comparing the ED revisit rates in the pre-COVID-19 and COVID-19 periods by age and revisit time intervals. Although the total number of ED visits decreases by 31.7% in the COVID-19 period compared to the pre-COVID-19 period, there is an increase in the ED revisit rate in the COVID-19 period among all age groups. However, there is no change in the pattern of revisit as the revisit rate increases with age in both pre-COVID-19 and COVID-19 periods.
Although the exact reasons for the increase in revisit rate in the COVID-19 period is unknown in this study, one possible reason could be the inadequate initial evaluation at the first visit. Some studies reported that the use of computed tomography and ultrasound decreased in the COVID-19 period [
]. The decrease in imaging studies could result in insufficient initial evaluations and limitations on accurate diagnosis; as a result, patients might have revisited the ED for further evaluations or management. Another possible explanation is that increased revisits because of the decrease in the admission of patients at the time of their first visit. The COVID‐19 pandemic required a significant allocation of healthcare resources, and it may have adversely affected the admission of non‐COVID‐19 patients. In other words, it is possible that the physicians were attempting not to admit patients at the time of the first visit unless absolutely necessary. In addition, there may be cases where patients were only tested for COVID-19 and revisit the ED after being confirmed negative because of the lack of isolation rooms on their first visit.
This study also shows that older patients still have higher revisit rates and higher ICU admission rates and mortality at the revisit than younger patients in the COVID-19 period. We previously found that the revisit rate, ICU admission rate, and mortality increased with age [
], and this trend did not change even during the COVID-19 period. However, when comparing the ICU admission rate and mortality at the revisit between the pre-COVID-19 and the COVID-19 period, there is a difference. The ICU admission rate for patients over 80 years is lower in the COVID-19 period than in the pre-COVID-19 period, while the ICU admission rate for all the other age groups is higher in the COVID-19 period. The mortality among patients more than 65 is also lower in the COVID-19 period than in the pre-COVID-19 period.
This result may be associated with a decrease in infectious and respiratory diseases. Wilhelms et al. reported that the most common causes of ICU admission among those older than 80 years were infection and respiratory diseases [
] and through this study, we found that the proportion of infectious and respiratory diseases at the revisits decreases. Thus, the decrease in infectious and respiratory diseases during the COVID-19 period may have contributed to the decrease in the proportion of ICU admission and mortality for patients more than 80 years of age.
There are some limitations in this study. First, we only use the data from the NEDIS database using the registration number of patients and do not analyze the medical records of each patient. Therefore, detailed data on revisit patients cannot be analyzed. We cannot determine whether the patients revisited the ED for the same symptoms as those reported in their index visits. To overcome this as much as possible, we only include patients who visited the ED for medical reasons, not including trauma. Second, as this is a retrospective study, we cannot confirm the purpose of the revisit and whether it was a scheduled or unscheduled visit. Third, this study only includes patients who revisited the same hospital they visited at the index visit. Thus, the revisit rates in this study may be an underestimate. Finally, as we only analyze ED revisits in tertiary university hospitals, the patients who visited primary clinics or secondary hospitals before visiting the tertiary university hospital could not be analyzed in this study.
Conclusion
In summary, the ED revisit rate increases in the COVID-19 period among all age groups and is higher among older patients than young patients in both periods. Our investigation also shows that the diagnosis and disposition of older patients at the revisits changes during the COVID-19 period, although there is no change in the overall revisit pattern. Therefore, further studies are needed to explain the reasons for these changes in older patients.
Funding
None.
CRediT authorship contribution statement
Myeong Namgung: Writing - original draft, Writing - review & editing, Data curation, Formal analysis, Dong Hoon Lee: Conceptualization, Methodology, Project administration, Supervision, Sung Jin Bae: Formal analysis, Investigation, Ho Sub Chung: Formal analysis, Investigation, Keon Kim: Formal analysis, Investigation, Choung Ah Lee: Investigation, Duk Ho Kim: Investigation, Eui Chung Kim: Investigation, Jee Yong Lim: Investigation, Sang Soo Han: Investigation, Yoon Hee Choi: Investigation.
Acknowledgements
None.
Disclosures
The authors declare no conflict of interest.
References
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et al.
Trends in emergency department visits and hospital admissions in health care systems in 5 states in the first months of the COVID-19 Pandemic in the US.
Comparative evaluation of the prognosis of septic shock patients from before to after the onset of the COVID-19 pandemic: a retrospective single-center clinical analysis.
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