A Randomized Controlled Trial of Biofire Film Array Gastrointestinal Panel Compared to Usual Care for Evaluation of Acute Infectious Diarrhea in the Emergency Department
Phase: NA
Conditions: Infectious Diarrhea
Sponsor: Andrew Meltzer

Title: Film Array Gastrointestinal Panel Compared to Usual 
Care for ED Evaluation of Infectious Diarrhea
“RCT of GIP in ED for ID”
or “RAPID”
ClinicalTrials.gov Identifier: NCT03809117
Interim Report
September 9, 2020
Prepared by the Section on Clinical Research
The George Washington University Department of Emergency Medicine
CONFIDENTIAL

Contents
Table of Contents
Title: Film Array Gastrointestinal Panel Compared to Usual Care for ED Evaluation of Infectious 
Diarrhea .......................................................................................................................................................1
Contents ......................................................................................................................................................2
Table of Contents .......................................................................................................................................2
Title Page.....................................................................................................................................................3
Introduction.................................................................................................................................................5
Background.................................................................................................................................................5
History of the Study....................................................................................................................................7
Statistical Methods.....................................................................................................................................8
Recruitment.................................................................................................................................................9
Screening Demographics ..........................................................................................................................9
Consort Diagram.......................................................................................................................................10
Reasons Ineligible ....................................................................................................................................11
Baseline Characteristics..........................................................................................................................12
Infection by Group....................................................................................................................................13
Outcomes ..................................................................................................................................................15
Follow-up Adherence and Compliance ..................................................................................................16
Side Effects and Adverse Events............................................................................................................20
Protocol Deviations/ Adherence .............................................................................................................20
References ................................................................................................................................................21

Figures
FIGURE 1: SCREENING BY MONTH..........................................................................................................9
FIGURE 2: CONSORT DIAGRAM .............................................................................................................10
Tables
TABLE 1: BASELINE CHARACTERISTICS OF THOSE WHO WERE SCREENED. .....................................9
TABLE 2: REASONS FOR EXCLUSION..............................................................................................................11
TABLE 3: BASELINE CHARACTERISTICS (N=87) ...........................................................................................12
TABLE 4: SUMMARY OF PATHOGEN DETECTED BY GIP BY TYPE..........................................................13
TABLE 5: SUMMARY BY CLASS OF INFECTION PER GROUP....................................................................14
TABLE 6: PARTICIPANTS REACHED FOR FOLLOW-UP OUTCOMES .......................................................15
TABLE 7: SUMMARY OF ED MANAGEMENT....................................................................................................16
TABLE 8: ANTIBIOTICS ADMINISTERED FOR DIARRHEA (ED OR AS PRESCRIPTION) ......................17
TABLE 9: FOLLOW-UP FOR SYMPTOMS..........................................................................................................18
TABLE 10: RETURN TO THE ED..........................................................................................................................18
TABLE 11: LOGISTIC REGRESSION RESULTS AFTER VARIABLE SELECTION.....................................19

Title Page
Andrew C. Meltzer, MD, MS
Associate Professor
Department of Emergency Medicine 
George Washington University (GWU) School of Medicine & Health Sciences 
Washington DC
Yan Ma, PhD, MA, MS 
Professor and Vice Chair 
Department of Biostatistics and Bioinformatics
George Washington University (GWU) Milken Institute School of Public Health
Washington DC
Yihe Huang, PhD Candidate
Department of Biostatistics and Bioinformatics
George Washington University (GWU) Milken Institute School of Public Health
Washington DC
Nataly Montano
Lead Research Coordinator and Data Management 
Department of Emergency Medicine 
George Washington University (GWU) School of Medicine & Health Sciences 
Washington DC
Sophia Newton
Gill Research Scholar 
Medical Student 
George Washington University (GWU) School of Medicine & Health Sciences 
Washington DC

Introduction
This report describes the work undertaken by the investigators for the “Film Array 
Gastrointestinal Panel Compared to Usual Care for ED Evaluation of Infectious Diarrhea 
study” also known as RCT of GIP for ID in ED or “RAPID.”  The single-center study was 
performed at the George Washington University Medical Center (GWU). The principal 
investigator for this study is Dr. Andrew Meltzer.
Background
For patients presenting to the emergency department (ED), real-time treatment 
decisions are predicated on rapid and accurate diagnosis. In the case of infectious 
diarrhea, traditional diagnostic tests have a low sensitivity and a long processing time 
and therefore are not useful in the ED for real-time treatment decisions. As such, 
physicians must treat diarrheal infection based on history of recent travel and high-risk 
clinical features. Rapid diagnosis and targeted treatment have only recently become 
possible with the introduction of multiplex polymerase chain reaction (PCR) panels that 
identify bacteria, viruses, and protozoa during a single ED visit. In this study, we aimed 
to determine if a rapid multiplex PCR test can lead to a more appropriate utilization of 
antibiotics for ED patients with infectious diarrhea. 
Gastrointestinal illness accounts for millions of cases per year in the US and results in 
approximately 500,000 hospitalizations and 5000 deaths.1 In general, the infectious 
agent is not identified. Norovirus and salmonella species are believed to account for 5.5 
and 1.0 million cases each year, respectively, and are the most commonly identified 
agents.2 The traditional stool culture is limited by time delay to results and low yield for 
identifying the cause of infectious diarrhea. In six studies conducted between 1980 and 
1997, the diagnostic yield of stool cultures ranged from 1.5 to 5.6 percent with a high 
cost to find a single positive.3 For admitted patients, the yield decreases over the 
hospital stay to 0.5% after 72 hours.3 Distinguishing viral causes from bacterial and 
protozoal causes is crucial because antibiotic treatment can reduce the severity of 
symptoms and the risk of future spread.3,4,5
Unfortunately, clinical findings may not be predictive of bacterial source. For example, 
neither bloody nor persistent diarrhea are associated with positive stool culture.6 
Typically, epidemiological risk factors serve as cornerstone of treatment decisions - 
ACG guidelines recommend that testing should be based on history of travel. In the 
absence of travel, antibiotics for routine community acquired diarrhea are discouraged 
due to the likelihood of viral etiology such as norovirus, rotavirus, and adenovirus.7 

Introduction of the rapid testing panels increases the identification of treatable 
pathogens in the ED and may improve our ability to provide infection control.8,9  A test-
and-treat strategy is feasible in the ED setting and could benefit symptomatic patients 
with gastrointestinal complaints.10 While there are several manufacturers with multiplex 
gastrointestinal testing panels, this study utilizes the FilmArray GI Panel which has a 
reported specificity of more than 95% for all panel targets.11
This interim report will summarize the progress of investigator-initiated randomized 
control trial:  Film Array Gastrointestinal Panel Compared to Usual Care for ED 
Evaluation of Infectious Diarrhea (ClinicalTrials.gov Identifier: NCT03809117) 
conducted with a grant from Biomerieux, Inc.

History of the Study
The RAPID study began in November 17, 2018 as an investigator-initiated funded study 
awarded to Dr. Andrew Meltzer in the Department of Emergency Medicine at the 
George Washington University in Washington DC. The study sponsor is Biomerieux, 
Inc.
A randomized control design was initiated where clinically stable patients in the ED with 
suspected infectious diarrhea were randomized to receive a rapid Gastrointestinal Panel 
(GIP) study or standard of care (SOC). The primary question was whether the use of a 
rapid diagnostic testing strategy improved the number of ED patients with bacterial 
diarrhea who received antibiotics. Additionally, this study sought to determine if there 
was a decrease in the number of patients with viral diarrhea who received antibiotics. 
The hypothesis was grounded on the following assumptions: 
 
Antibiotics are generally recommended in patients with bacterial diarrhea and 
contraindicated for viral diarrhea.  

The clinical distinction between viral and bacterial diarrhea can be challenging. 

Accurate identification of the causative agent allows the clinician to target 
treatment for patients with bacterial causes. 
The Biofire FilmArray GI Panel received U.S. Food and Drug Administration (FDA) 
510(k) clearance for the FilmArray® Gastrointestinal (GI) Panel in May 2014. The test 
consists of automated nucleic acid extraction, reverse transcription, amplification, and 
analysis, with results available in 1 hour per run per specimen. The FilmArray GI Panel 
detects seven bacteria (Aeromonas spp., Campylobacter spp. [C. jejuni, C. coli, and C. 
upsaliensis], C. difficile toxin A/B, P. shigelloides, Salmonella spp., Vibrio spp. [V. 
parahaemolyticus, V. vulnificus, and V. cholerae with specific detection of V. cholerae], 
and Y. enterocolitica), six diarrheagenic Shigella spp./E. coli (enteroaggregative E. 
coli [EAEC], enteropathogenic E. coli [EPEC], enterotoxigenic E. coli [ETEC], 
enteroinvasive E. coli [EIEC]/Shigella spp., Shiga-like toxin-producing E. coli [STEC] 
[with specific detection of E. coli O157]), four parasites (Cryptosporidium, Cyclospora 
cayetanensis, E. histolytica, and G. lamblia), and five viruses (adenovirus F 40/41, 
astrovirus, norovirus GI/GII, rotavirus A, and sapovirus). Each FilmArray GI Panel pouch 
contains an internal nucleic acid extraction control and a PCR control. The FilmArray GI 
Panel runs were considered valid if the run is completed normally and internal controls 
are passed. The FilmArray GI Panel software performs automated result analysis with 
each target in a valid run reported as detected or not detected. 
The GW IRB approved the trial by a full board on June 1, 2018. Study was renewed on 
June 2019 and June 2020. Study was registered on clinicaltrials.gov on January 18, 
2019. First patient was enrolled in November 17, 2018. In March 15, 2020 as the SARS-
CoV-2 crises reached epidemic and subsequently pandemic levels, the study was put 
on hold. At this time, study investigators paused to perform an interim analysis and hold 
a full meeting regarding the next steps and modifications that need to be made moving 
forward.

Statistical Methods
In this report, individual participants are denoted by their patient number, a unique 
identifier. In the tables, “N” refers to the number of observations with non-missing values 
for the variable. The p-values reported are nominal p-values. Unless otherwise 
specified, they are based on the usual chi-square statistic (or Fisher’s exact test in the 
case of infrequent outcomes) for discrete variables or the Wilcoxon Rank Sum test for 
continuous variables. Although data for some participants may be missing, all relevant 
data available from each participant will be employed in the analyses.  
In planning this study, in order to detect a 20% improvement in appropriate antibiotics, 
we need 88 patients in each group to detect a difference of 80% versus 60% with 95% 
confidence and 80% power. The sample size was adjusted to take into consideration 
losses.

Recruitment
In the GW ER, there were 663 screenings. Figure 1 shows the 87 randomizations for 
the multi-center study by month and year.
Figure 1: Screening by month.
Screening Demographics
The demographics obtained for each screening are gender, race and ethnicity as shown 
below. Missing data was excluded.
Table 1: Baseline characteristics of those who were screened.
Characteristic
N 
% Screened*
*(missing excluded)
Female
359
54%
Non-white race
126
19%
Hispanic
22
3% 

663 patients assessed for 
eligibility
576 excluded
* Not meeting inclusion criteria (n=65)
* Meeting exclusion criteria (n=119)  
* Declined to participate (n=68)
* Other reasons (n=226)
43 assigned to Group 1
(ITT population)
41 stool collection;
38 received stool analysis
(Per protocol population)
87 underwent 
randomization
38 followed to clinical 
outcome after ED discharge 
(Secondary Outcome)
36 followed to clinical 
outcome after ED discharge
(Secondary Outcome)
38 reviewed for ED 
prescription of antibiotics 
(Primary Outcome)
44 assigned to Group 2 
(ITT population)
44 stool collection;
36 received stool analysis
(Per protocol population)
36 reviewed for ED 
prescription of antibiotics
(Primary Outcome)
(Per protocol population)
Consort Diagram
A CONSORT diagram is shown in Figure 2. There were 663 screenings resulting in the 
87 (13%) randomizations.  Of the 663 screenings, there were 68 (12%) who declined to 
participate. Full list of exclusion is included in Table 2.  The biggest single reason for 
exclusion was that a stool sample was not provided. Of the 87 randomized participants, 
only 76 patients provided stool samples and were randomized to either Group 1 or 
Group 2.
Figure 2: CONSORT Diagram

Reasons Ineligible 
For patients who were excluded, the reasons for being excluded are presented in Table 
2.  A majority were excluded due to meeting multiple exclusion criteria. 
Table 2: Reasons for Exclusion
Reason for Exclusion
Number of Patients
Record incomplete
8
Presumed non-infectious diarrhea
36
Inadequate clinical evidence
21
Chronic symptoms (>14 days)
49
Likely non-infectious cause of diarrhea (IBD, IBS, etc.)
41 
Confirmed Clostridium difficile infection
7 
Patient unable to consent
16
Inability to follow up
6 
Refused to participate
68 
Stool sample not provided
94 
Multiple exclusion criteria met
226 
Other
4 

Baseline Characteristics 
The full cohort of participants who provided stool for collection is shown below with the 
baseline characteristics by treatment group. The treatment groups are well-balanced 
with respect to characteristics at baseline.
Table 3: Baseline characteristics (n=87)
Group 1 (n=43)
Group 2 (n=44)
Median Age at Screening (yr)
36
35
Female (%)
26 (60.5)
20 (45.5)
Black (%)
26 (66.7)
25 (62.5)
White (%)
10 (25.6)
12 (30.0)
Asian, Native American, Pacific Islander, 
Unknown (%)
3 (7.8)
3 (7.5)
Hispanic or Latino (%)
6 (14.6)
8 (19.5)
Not Hispanic or Latino (%)
35 (85.4)
33 (80.5)
Three or more loose stools in the past 24 
hours (%)
41 (100.0)
44 (100.0)
Symptoms greater than 24 hours? (%)
33 (76.7)
33 (75.0)
Dehydration? (%)
30 (69.8)
25 (56.8)
Vomiting, reported by patient (%)
29 (67.4)
28 (63.6)
Abdominal Pain, reported by patient (%)
37 (86.0)
37 (84.1)
Fever, reported by patient (%)
15 (34.9)
16 (36.4)
Symptoms lasting more than 7 days? (%)
1 (2.3)
2 (4.5)
Heart Rate (bpm, median, at triage) *
93.00 [86.00, 105.00] 84.50 [75.50, 97.25]
Systolic Blood Pressure (mmHg, median, 
at triage) *
126.00 [117.50, 
137.00]
132.50 [123.00, 
147.25]
Temperature
98.20 [97.90, 98.60]
98.40 [98.05, 98.65]
Recent Travel (%)
9 (20.9)
14 (31.8)
Prescription antibiotics (%)
3 (7.0)
3 (6.8)
* P value< 0.05

Infection by Group
Table 4 summarizes the pathogens per group for all participants who had a stool 
sample analyzed.
Table 4: Summary of pathogen detected by GIP by type
Group 1 (%)
n=38
Group 2 (%)
n=36
Campylobacter (%)
4 (10.5)
3 (8.3)
Clostridium difficile toxin A/B (%)
1 (2.7)
2 (5.7)
Plesiomonas shigelloides (%)
0
0
Salmonella (%)
1 (2.6)
2 (5.6)
Vibrio, non-cholerae (%)
1 (2.6)
0 (0.0)
Vibrio cholerae (%)
1 (2.6)
0 (0.0)
Yersinia enterocolitica (%)
0
0
Enteroaggregative E. Coli (EAEC) (%)
2 (5.3)
5 (13.9)
Enteropathogenic E. Coli (EPEC) (%)
3 (7.9)
6 (16.7)
Enterotoxigenic E. Coli (ETEC) (%)
2 (5.3)
1 (2.8)
Shiga-like toxin-producing E. Coli (STEC) stx1/stx2 (%)
0
0
Shigella/Enteroinvasive E. coli (EIEC) (%) *
5 (13.2)
0 (0.0)
Cryptosporidium (%)
0 (0.0)
2 (5.6)
Cyclospora cayetanensis (%)
0
0
Entamoeba histolytics (%)
0
0
Giardia lamblia (%)
1 (2.7)
0 (0.0)
Adenovirus 40/41 (%)
0 (0.0)
2 (5.6)
Astrovirus (%)
0 (0.0)
1 (2.8)
Norovirus GI/GII (%)
13 (34.2)
7 (19.4)
Rotavirus (%)
2 (5.3)
2 (5.6)
Sapovirus (%)
1 (2.6)
1 (2.8)
* P= 0.021

Infections were summarized by class of infectious agent as bacterial or protozoa or 
virus. 
Table 5: Summary by class of infection per group
Group 1 (%)
Group 2 (%)
Total
Bacteria
11 (28.9)
9 (25.0)
20
Bacteria + virus
3 (7.9)
2 (5.6)
5
Parasites
1 (2.6)
2 (5.6)
3
Not detected
11 (28.9)
13 (36.1)
24
Virus only
12 (31.6)
10 (27.8)
22
Total
38
36
74

Results / Outcomes
The primary clinical question is whether the use of PCR was associated with a change 
in management, specifically appropriate use of antibiotics as defined as antibiotics for 
bacteria or protozoa and not for virus. For all 74 patients who provided stool samples, a 
chart review was completed to assess ED management. Follow-up telephone contacts 
were also conducted for all participants and were attempted at post-randomization days 
2, 7 and 30. (Table 6) Follow-up attempts were made at least four times with calls at 
different times before participant was considered lost to follow-up. No participants 
withdrew consent after the time of enrollment. Overall, attempted contacts were 
documented for 100% of those expected.  
Enrollment and follow-up
Table 6: Participants reached for follow-up outcomes
Group 1
Group 2
Total
Number Randomized
43
44
87
Number Analyzed 
38
36
74
Number Reached at Day 2 
30
25
55
Number Reached at Day 7
26
24
50
Number Reached at Day 30
32
36
68

ED Management 
In table 7, we demonstrate, that patients in group 1 were more likely to receive 
antibiotics in the ED (p=0.021) for any cause. 
Table 7: Summary of ED Management 
7a: per protocol analysis
ED Management
Group 1
(n =38)
Group 2
(n=36)
Antibiotics given in ED for Diarrhea (Name, Dosage) (%) 
10 (26.3)
3 (6.8)
Antibiotics Prescribed for Diarrhea (%)
13 (34.2)
8 (22.2)
IV Rehydration Therapy? (%)
Lactated Ringers / Normal Saline
31 (81.6)
25 (69.4)
Antidiarrheal Medication Prescribed (%)
4 (10.5)
2 (5.7)
Admitted to Hospital
7(18.4)
3 (8.3)
Computed Tomography ordered (%)
8 (21.1)
8 (22.2)
Length of Stay (in hours) (median [IQR])
7.68 [6.43, 
10.67]
8.15 [5.90, 
11.23]
7b: ITT analysis (includes all patients randomized) 
ED Management
Group 1
(n = 43)
Group 2
(n = 44)
Antibiotics given in ED for Diarrhea (Name, Dosage) (%) *
11 (25.6)
3 (6.8)
Antibiotics Prescribed for Diarrhea (%)
14 (32.6)
8 (18.2)
IV Rehydration Therapy? (%)
Lactated Ringers / Normal Saline
34 (80.1)
31 (72.1)
Antidiarrheal Medication Prescribed (%)
4 (9.3)
3 (7.0)
Admitted to Hospital
8 (18.6)
3 (7.0)
Computed Tomography ordered (%)
10 (23.3)
8 (18.2)
Length of Stay (in hours) (median [IQR])
7.87 [6.45, 
10.55]
8.15 [5.90, 
10.76]
* p-value = 0.021

Antibiotics by Group 
A primary question of the study is the appropriate use of antibiotics for bacterial 
diarrhea. In Group 1, antibiotics were given for 87% of patients with bacterial or 
protozoal infection versus Group 2 in which patients were given antibiotics in 46% of 
bacterial or protozoal infections.  (Table 8)
Table 8: Antibiotics Administered for Diarrhea (ED or as Prescription)
Group 1
Group 2
Antibiotics given for Bacterial or Protozoal 
Infection
13/15 
0.87, (0.62. 0.96)
6/13
0.46, (0.23, 0.71)
Antibiotics Given for Viral Infection
1/12
1/10
Antibiotics given for None detected
3/11
2/13
Table 8a. Antibiotics given for any reason
Group
1
2
p-value
n
38
36
Antibiotics? (%)
No
21 (55.3)
27 (75.0)
0.125
Yes
17 (44.7)
9 (25.0)
Table 8b. Antibiotics given for Bacteria /Protozoa
Group
1
2
p-value
n
15
13
Antibiotics? (%)
No
2 (13.3)
7 (53.8)
0.042
Yes
13 (86.7)
6 (46.2)
Table 8c. Antibiotics given for viral infection
Group
1
2
p-value
n
12
10
Antibiotics? (%)
No
11 (91.7)
9 (90.0)
1
Yes
1 (8.3)
1 (10.0)
Table 8d. Antibiotics given for none detected
Group
1
2
p-value
n
11
13
Antibiotics? (%)
No
8 (72.7)
11 (84.6)
0.63
Yes
3 (27.3)
2 (15.4)
Without Bonferroni correction in multiple test, the test for Table 8b for antibiotics given 
for Bacteria /Protozoa is significant with p-value of 0.042. If you consider the Bonferroni 
correction, a new alpha-level = 0.05/3 = 0.0167 which is less than 0.042.

Follow-up Adherence and Compliance 
In Table 9, we see a non-significant trend toward improved symptoms in group 1 versus 
group 2. (p-value 0.37)
Table 9: Follow-up for Symptoms
Grp1
Grp2
Day2: Do you still have the same symptoms as when you came to the 
Emergency department? (%)
12 (41.4)
11 (50.0)
Day7: Do you still have the same symptoms as when you came to the 
Emergency department? (%)
2 (7.7)
4 (20.0)
Day30: Do you still have the same symptoms as when you came to the 
Emergency department? (%)
2 (6.2)
4 (14.8)
16 (42%)
19 (53%)
        
In Table 10, we compared return visits for those in group 1 versus group 2. (p-value 
0.51)
Table 10: Return to the ED
Grp1
Grp2
Day2: Have you returned to any Emergency department for similar 
symptoms? (%)
0 (0.0)
0 (0.0)
Day7: Have you returned to any Emergency department for similar 
symptoms? (%)
0 (0.0)
1 (5.0)
Day30: Have you returned to any Emergency department for similar 
symptoms? (%)
1 (3.3)
1 (3.7)

Clinical differences between bacterial and viral infection
A model was created to determine if there were clinical or historical factors associated 
with bacterial infection.
Table 11: Logistic regression results after variable selection
Odds Ratio Estimates
Effect
Point
Estimate
95% Wald
Confidence Limits
When did this episode of diarrhea start?  (2 days or greater) vs 
(Less than 24 hours ago)
16.618
1.362
202.728
Vomiting (Yes) vs (No)
0.002
<0.001
0.190
Fever (Yes) vs (No)
11.279
1.025
124.168
Triage Pulse (bpm)
0.896
0.803
1.000
Triage SBP (mmHg)
0.916
0.833
1.007
SpO2 (%)
0.548
0.233
1.288
Temperature (Fahrenheit)
8.638
0.694
107.471
Coefficient Estimate
Parameter
Estimate
Standard
Error
P-value
Intercept
-129.5
119.8
0.2797
Greater than or equal 2 days of diarrhea
2.8105
1.2762
0.0277
Vomiting
-6.1649
2.2979
0.0073
Fever
2.4230
1.2238
0.0477
Triage Pulse (bpm)
-0.1099
0.0561
0.0502
Triage sbp (mmHg)
-0.0878
0.0485
0.0702
SpO2 (%)
-0.6018
0.4361
0.1676
Temperature (Fahrenheit)
2.1561
1.2863
0.0937

Side Effects and Adverse Events 
There were no adverse events reported for the study.  For serious adverse events, the 
study employs the definition used by the FDA which is: death, life-threatening, 
hospitalization, disability, congenital anomaly, or other interventions.  No reported 
events were considered serious per the above definition. 
Protocol Deviations/ Adherence
There was one protocol deviation in study.  The protocol deviation related to the plan to 
get additional consent from participants to keep samples for future studies.  
Unfortunately, due to miscommunication with staff, most participants were not asked to 
specifically sign the additional question on the consent form. As a result, we were forced 
to destroy most of the samples.  This deviation had no effect on the current study and 
only affects opportunities to do future additional studies. 

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