Introduction
The rapid spread of coronavirus disease 2019 (COVID-19) and its debilitating impact
on health systems has led to a global health crisis of unprecedented proportions.
Health care workers (HCW) exposed to aerosols and tracheobronchial droplets during
gastrointestinal endoscopy are at a higher risk of infection [1]. In addition, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has been
isolated in the feces of patients with COVID-19, raising the question of a possible
fecal-oral route of transmission [2].
For these reasons, pre-procedure screening of patients presenting for endoscopy has
been suggested in various recommendations [3]
[4]
[5]. Routine pre-endoscopic screening could have enormous advantages for infection prevention
and control in endoscopic departments. The European Society of Gastrointestinal Endoscopy
(ESGE) position statements recommend pre-endoscopic risk stratification by questioning
for symptoms and positive history one day before and on the day of endoscopy [3]. Furthermore, it is recommended that highly elective examinations may temporarily
be postponed. A key point of the recommended screening strategy is strict viral testing
using molecular diagnostic tests, such as polymerase chain reaction (PCR), if available.
Besides standard PCR, widely used rapid antigen tests are available for the detection
of SARS-CoV-2 infection. These tests can be performed as an antigen point-of-care
test (Ag-POCT) in the immediate proximity of the endoscopy unit. However, the position
paper does not recommend Ag-POCTs due to insufficient data [6].
In the endoscopy unit of Augsburg University Hospital, pre-procedure risk stratification
was performed according to the recommendations in the ESGE position statement using
a two-stage pre-procedure questionnaire 1 to 2 days prior to a patient’s appointment
as well as on the day of their presentation to the endoscopy unit. In addition, especially
during the peak of the second wave in November and December 2020 (Supplement 1), highly
elective examinations such as surveillance of post-polypectomy or post-surgery colorectal
cancer patients were postponed. Besides the standard PCR test, Ag-POCTs were performed
in all patients to generate real-life data for a prospective evaluation of this test
method.
Pre-endoscopic screening procedures are resource-sensitive and cost-intensive [6]; in addition, data on the effectiveness of these measures in endoscopic facilities
are lacking. In this study, data on the effectiveness of pre-endoscopic risk management
and testing recommended by ESGE in a high-volume endoscopic center in Germany during
the second wave of the COVID-19 pandemic are presented.
Patients and methods
Patient screening
We analyzed all outpatients who presented to the endoscopy unit of the Augsburg University
Hospital between 01.07.2020 and 31.12.2020.
Pre-endoscopic risk management was performed according to the recommendations in the
ESGE position statements [3]
[7]. For this purpose, patients were screened for COVID-19 using a two-stage pre-procedure
questionnaire for risk stratification, 1 to 2 days prior to their appointment as well
as on the day of their presentation to the endoscopy unit (Supplement 2). After questionnaire-based
risk stratification, patients were tested with an antigen-POCT (standard F Covid19
Ag FIA/SD; Co. Biosensor). In addition, most patients also underwent a standard PCR
test (see supplemental material). A flowchart showing the exact procedure in our endoscopy
unit is demonstrated in [Fig. 1]. For the antigen-POCT and the standard PCR test, nasopharyngeal or oropharyngeal
swabs were taken by appropriately trained staff members in a separate room of the
endoscopy unit on the day of the procedure. The study was conducted in accordance
with the Declaration of Helsinki and Good Clinical Practice guidelines. Ethics approval
was granted by the Ethics committee of the Ludwig-Maximilians-Universität München
(EK-Nr. 20-1052).
Fig. 1 Screening strategy in the endoscopy unit for outpatients. Ag-POCT, antigen point-of-care
test; COVID-19, corona virus disease 2019; PCR, polymerase chain reaction; PPE, personal
protective equipment; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.
Simulation of expected COVID-19 case numbers and number of cancelled or postponed
procedures
The catchment area of Augsburg University Hospital was defined using controlling data
from previous years. The prevalence in the population in the given catchment area
was carried out following Sultan et al. (2020), and a theoretically expected number
of cases of SARS-CoV-2 positive patients was calculated as follow [8]:
-
The cumulative number of cases was provided by the Bavarian State Office for Health
and Food Safety for each day of the study period.
-
The number of new cases was calculated as a difference between the cumulative number
of cases on the previous day and the cumulative number of cases on the current /considered
day,
-
Using the daily data from the previous step, the cumulative number of active cases
for the past 14 days was calculated.
-
In line with Forde et al. [9] and Benatia et al. [10], the number of active cases was adjusted for the SARS-CoV-2 positive population
in the catchment area by multiplying by 10.
-
The population in the catchment area was determined using information provided by
the Bavarian State Office for Health and Food Safety.
-
The number of expected SARS-CoV-2-positive patients was determined by dividing the
adjusted number of active cases within the population in the catchment area and multiplying
by the number of patients regularly scheduled in the outpatient's endoscopy unit within
the study period.
To obtain the reduction in total case load and an estimate for the number of examinations
cancelled or postponed, we compared the case numbers for the study period with those
for the previous year.
Employee screening
We retrospectively evaluated rapid antibody tests (NADAL COVID-19 IgG/IgM) performed
in the last week of the study period among employees and staff of the endoscopic outpatient
department.
Results
Examination volume and pre-endoscopic risk management
The expected examination volume between July and December 2020 estimated using prior-year
data was 1276 procedures in 733 patients ([Fig. 2]). A total of 238 procedures in 137 patients (18.7 %) were cancelled between July
and December 2020, of which, 185 procedures in 106 patients were cancelled or postponed
during the peak of the second wave of the pandemic in November and December.
Fig. 2 Screening data for the study period. Ag-POCT, antigen point-of-care-test; COVID 19,
corona virus disease 2019 ESGE, European Society of Gastrointestinal Endoscopy; PCR,
polymerase chain reaction; SARS-CoV-2, severe acute respiratory syndrome coronavirus
2.
Examinations and procedures were cancelled or postponed due to COVID-19-like symptoms,
a positive history in the pre-endoscopic screening questionnaire, or due to a highly
elective indication. A total of 596 patients (81.3 %) with 1038 planned procedures
presented to the endoscopy unit and underwent pre-endoscopic risk stratification in
the endoscopy unit. Five patients (1.0 %) were sent home without further testing or
intervention on the day of pre-procedure screening due to high-risk stratification
according to the questionnaire. Two of them had recently travelled to a high-risk
area and three of them had COVID-19-related symptoms.
A total of 591 patients were tested with the Ag-POCT, of which, 529 (89.5 %) received
a standard PCR test in parallel. The antigen test provided a result within 20 minutes,
while the results of the standard PCR test were available with a time delay of up
to 24 hours.
Of the 1029 procedures performed, 636 (61.8 %) were endoscopies of the upper gastrointestinal
tract (543 gastroscopies, 1 endoscopic retrograde cholangiopancreatography, 92 endoscopic
ultrasounds).
Results of the Ag-POCT
Ag-POCT was positive in one patient (0.2 %) but with a negative standard PCR test
while one other patient tested positive with standard PCR test but negative in the
Ag-POCT. However, this patient had a high cycle threshold (CT) value of 35.6.
Expected COVID-19 case number
The simulations were performed as described in the methods section. The expected case
number of SARS-CoV-2 positive patients for the study period was 15.
Employee screening
Fourty-three employees/health care workers in the endoscopy department underwent an
antibody rapid test. One endoscopy nurse had a positive result while 42 were negative.
All workers were asymptomatic on the day of the test.
Discussion
In this paper, we present real-life data on the effectiveness of pre-endoscopic risk
management according to the recommendations of the ESGE in a high-volume endoscopic
center in Germany during the second wave of the COVID-19 pandemic.
The study was conducted in Augsburg which has been a local hotspot during the ongoing
second wave of the pandemic. Seven-day incidence rates as high as 400 per 100,000
were reported for the region [11].
The calculated number of expected SARS-CoV-2-positive patients, taking into account
the daily prevalence in the catchment area, was 15. This number is in contrast to
the one patient who tested positive via PCR test. We believe the reason for the low
number of detected cases was the strict questionnaire-based risk stratification performed
via telephone, 1 to 2 days prior to the intervention, as well as on the day of the
intervention. It is also possible that the temporary postponement of highly elective
procedures may have resulted in a decreased number of SARS-CoV-2-positive patients
presenting to the endoscopy unit. According to the simulation based on the prevalence
and incidence rates in the region, about 14 additional patients with COVID-19 should
have presented to the unit. However, the estimated number of unreported cases in Germany
seems to be overestimated with a factor of 10. Other sources suggest a factor of three
to five [12]
[13]. In this case, however, there would still have been an expected five to eight patients
instead with a SARS-CoV-2 infection.
With only one positive PCR test result and one positive result in the Ag-POCT, it
is not possible to correctly estimate the sensitivity and specificity of the Ag-POCT.
The patient who tested positive in the Ag-POCT had a negative PCR test. The patient
had previously been tested positive several times in the Ag-POCT. However, the PCR
test had always been negative and there was no history of previous disease. For this
reason, we assume the Ag POCT to have been false positive in this case presumably
due to bacterial colonization [14]. In the PCR test-positive patient, the CT value was 35.6, which implies a low pharyngeal
viral load [15]. Because the PCR test result was received about 24 hours later, all health care
workers involved in the direct care of this patient underwent clinical follow-up and
testing but remained negative and asymptomatic. After receiving the positive PCR test
result, the patient was sent to home isolation according to the orders of the local
health department. However, the patient did not have any COVID-19 typical symptoms
at any time.
A further indication for the effectiveness of the risk-management measures is the
low number of infected employees within the unit. Only one endoscopy worker (2.3 %)
had a serologically detectable history of past infection, which had been acquired
within the private family environment. Of course, all recommended personal protective
equipment (PPE) standards were used routinely for all endoscopy procedures irrespective
of the pre-endoscopy risk-stratification.
Our findings are in line with publications by Recipi et al. and Hayee et al., who
described the use of PPE and reduction of elective procedures as a useful tool for
SARS-CoV-2 infection prevention [16]
[17].
The Ag-POCT, which was part of our study evaluation, is cheap, widely available, easily
performable at the point-of-care, and produces results within 20 minutes [18]. However, real-life data on test accuracy in endoscopy units are lacking.
Nevertheless, Ag-POCT may be considered in combination with questionnaire-based risk-stratification
and use of the recommended PPE for units without access to the resource-intensive
and significantly more expensive molecular diagnostic PCR test. The approval of COVID-19
vaccines in the last few months, and the widespread vaccination of endoscopy health
care workers, may require an adjustment of the recommendations presented in this study.
The major limitation of this study is the retrospective evaluation, which made it
difficult to evaluate the exact number of patients whose procedures were cancelled
specifically due to a high-risk stratification via telephone. However, most elective
endoscopic examinations were continued during the second wave of the pandemic, which
means that a greater number of cancelled or postponed procedures can be attributed
to a high-risk stratification according to the questionnaire.
A further limitation is the low number of SARS-CoV-2-positive PCR test results (n = 1)
produced during the study period, making the planned direct prospective comparison
between the Ag-POCT and PCR tests impossible. However, and as described above, the
low number of positive patients can be attributed to the risk-stratification approach
described above.
Conclusions
In conclusion, pre-endoscopic risk management recommended by ESGE, especially questionnaire-based
risk stratification in conjunction with viral testing, seems to be an effective tool
in combination with PPE for SARS-CoV-2 infection prevention and control within the
endoscopy unit even in a high-prevalence setting.
