Review for 10.1186/s12876-021-01616-9 (2021)

Reviewer’s report
Title: 
Clinical and endoscopic features of aorto-duodenal fistula resulting in its
definitive diagnosis: an observational study
Version: 
1 
Date: 
15 Nov 2020
Reviewer's report:
The paper by Chikamasa Ichita et al is a retrospective analysis of baseline
characteristics and diagnostic pathway of patients with aorto-duodenal fistula
(ADF) who underwent endoscopy before definitive diagnosis. Authors found 8
patients in a 11-year period with these criteria, thus underlying the rarity of the
condition. In literature are already present some case series about this rare
condition, however they are all quite dated. Thus, the paper may be of interest
allowing to increase knowledge about this condition among gastroenterologists
and endoscopists. In particular, I think that the main value of the paper is to
describe the endoscopic appearance of this rare condition (mainly indirect signs
of the fistula rather than exposure of aortic stents).
The paper, however, has some important limitations. Authors included only
patients who underwent endoscopy before definitive diagnosis (and not all the
patients presenting with ADF to the emergency department). I may suppose that
a proportion of patients with high suspicion of ADF could have received a
definitive diagnosis by CT scan used as first-line diagnostic test (thus bypassing
endoscopy) or died due to exsanguination before endoscopy. If this is true, the
paper could provide incomplete information about the real incidence of the
condition, its outcome and an unreal picture of the diagnostic and therapeutic
pathway of patients with suspected ADF. 
Some importante data are missing, first of all timing of endoscopy but also vital
signs, data about blood transfusion. 
The main issue about the paper is, however, the confusion in the presentation of
data, mixing methods, results and discussion. The paper should receive a deep
reorganization (and a linguistic revision) before to be considered for publication. 
Comments: 
- Abstract: 
o Background section of the abstract is too long, especially if compared to
results section. Please try to summarize 
o In the methods section, add "definitive" before diagnosis in order to increase
clarity
o Results section needs to be implemented: for example, patients' age, number of
patients presented with shock, number of patients who underwent CT scan as the
first test and number of patients who underwent primary endoscopy should be
reported. Endoscopic findings should be reported also as percentages. 
o Conclusions should be more focused on data reported in the abstract
- Introduction: 
o Please report here references of previously published case reports and series
mentioned in lines 44 and 45
o In line 47 It is stated that "many cases" have been treated in authors' institution.
However, I'm not sure that 8 cases can be defined "many", even taking into
account the rarity of the condition. I suggest to modify many with "a relatively
high number of cases"
o I suggest to reformulate the aim of the study (line 29)
- Methods section should be implemented: 
o Were these eight patients all the consecutive patients accessing to the hospital
for ADF in the study period? Is it otherwise possible that any patient with ADF
did not receive endoscopy because of definitive diagnosis by first-line CT scan
or died before endoscopy? This information should be provided here and
discussed in the discussion section (see below)
o Diagnostic criteria for definitive and suspected diagnosis, for either CT scan or
endoscopy should be reported in a clearer manner. CT findings and their
meaning should be presented in this section, and not in the results/discussion.
Moreover, you should discuss how to interpret a case in which both endoscopy
and CT scan provide only signs of suspicion 
o Definition of shock should be provided. 
o A statement about the collection of WBC count and CRP protein in these
patients and their meaning (exploring the possibility of infection) should be
inserted. 
o Information content in Lines 71-74 should not be reported in the methods but
somewhere in the results session. About this patient, once ADF was treated with
aortic stent placement, what was the meaning of repeated endoscopy?
o Was a tip attachment used in all cases? Is this a routinary choice in your center
for all upper gastrointestinal bleeding or you only do it in case of suspected ADF
(for example after a CT scan suggesting this condition)? 
- Results section:
o All the results are reported in a confusing order. Globally speaking, the entire
section should be entirely rewritten. In particular, I suggest to follow the
flowchart (picture 6) while describing the clinical pathway of the patients (start
describing how many patients underwent CT scan first and how many endoscopy
etc…) 
o Can you try to compare (or at least discuss) baseline characteristics of patients
who underwent CT scan before endoscopy with patients who underwent
endoscopy first? Which characteristics guided the choice of the first-line
diagnostic test? This could provide very useful information about the most
correct management of these patients (this aspect should also be analyzed in the
discussion) 
o For the same reason, can you discuss what lead to the choice of pediatric
colonoscopes (instead of standard gastroscopes) in two patients? In these
patients was CT scan performed before endoscopy? 
o Vital signs (heart rate, blood pressure) at the moment of presentation should be
reported, according to what is stated in the methods section
o After how many hours from presentation was endoscopy performed? Can you
provide this crucial information about timing of endoscopy?
o Data about blood transfusions are missing
o Among chief complaints you have not reported syncope (that is however
reported in table 1 for patient 1). 
o Have the endoscopic clips positioned during primary endoscopy been useful
for the final diagnosis on CT-scan? Report if the CT scan alterations were found
adjacently to the clips
- Discussion section is also confusing and there are many repetitions
o If some patients with ADF were not included (because they did not undergo
endoscopy; see the comment above), discuss the role of endoscopy in ADF on
the light of this information. If this information is not available, you should
discuss this important study limitation (underestimated incidence of the
condition, possible overestimation of survival).
o You should try to provide useful suggestions to physicians and
gastroenterologists involved in the care of patients with gastrointestinal bleeding.
In which patients ADF should be suspected? When do you suggest performing
CT scan as first-line test and when endoscopy? What is your recommended
timing for endoscopy in patients with suspected ADF? 
Should we always use
long scopes and tip attachements?
o Discuss the utility of clips placement
- Conclusions are not very consistent and should be completely reformuled
- I strongly suggest a linguistic revision by a mother tongue reviewer
Minor concerns: 
- Line 50: I suggest to add the word "standard" or "regular" before to "upper
gastrointestinal bleeding"
- Line 83: specify the reason why the patient underwent para-aortic radiation
- Table 1: the percentage of patients with aorta and duodenum adjacent to each
other (CT findings) is 100% and not 33.3%
- Table 2: Please provide the precise age of each patient. Include vital signs (if
available). Report the type of scope used here (gastroscope or pediatric
colonoscope). I suggest changing the term underlying disease with
Comorbidities. Provide scientific name of drugs instead of commercial name (I
could not even find which drug Panardin is on Google…).
- Hb levels are always erroneously reported as mg/dl, while the correct value is
g/dl
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Is the study design appropriate to answer the research question (including the use
of appropriate controls), and are the conclusions supported by the evidence
presented?
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Yes
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No
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from apparent manipulation?
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