Review for 10.1186/s12876-022-02427-2 (2022)

Title: Deep learning as a novel method for endoscopic diagnosis of chronic atrophic gastritis:
a prospective nested case-control study
Version: 1 Date: 30 May 2022
Reviewer's report:
Comments to the Author
I reviewed with great interest the manuscript entitled “Deep learning as a novel method for
endoscopic diagnosis of chronic atrophic gastritis: a prospective nested case-control study” in
BMC Gastroenterology.
The aim of this study is important. However, I found various issues, which are described below.
Major points
1. Most of the references are from China, and as an international journal, it is necessary to
describe the entire paper based on references from other Asian countries such as Japan and
Korea, as well as from Europe, the U.S., and other countries.
2. However, in order to describe the purpose of the study, which is to compare the diagnostic
performance of AI and endoscopists, the description of AI should be reduced and other methods
and definitions should be described. For example, is the biopsy site grater curvatures or lesser
curvatures, and where is the body part? Is the degree of atrophy determined by histology or the
extent of atrophy? If only tissue is used, which site is used to determine the extent of atrophy?
How is H. pylori diagnosed and what are the criteria for a negative or positive result?
3. Atrophy is common even in H.pylori negative patients in this study, what is the cause of this
atrophy? There are more than 25% H.pylori positive without atrophy, but what type of gastritis
is this?
4. There is a lot of overlap between this paper and the prior paper, "Deep learning model can
improve the diagnosis rate of endoscopic chronic atrophic gastritis: a prospective cohort study".
There are also many overlapping statements in the introduction and discussion sections of the
paper. Please clearly describe the differences from the previous paper in terms of methods,
results, and conclusions.
5. The Kimura-Takemoto classification is well known as an endoscopic diagnosis of atrophic
gastritis and has been reported to be strongly associated with histological atrophy as well. since
what AI recognizes is also an endoscopic image, please discuss this point as well, citing the
following literature.
1#  Kimura K, Takemoto T. An endoscopic recognition of the atrophic border and its significance
in chronic gastritis. Endoscopy 1969; 1: 87-97 [DOI: 10.1055/s-0028-1098086]
2# Sugano K, Tack J, Kuipers EJ, Graham DY, El-Omar EM, Miura S, Haruma K, Asaka M,
Uemura N, Malfertheiner P; faculty members of Kyoto Global Consensus Conference. Kyoto
global consensus report on Helicobacter pylori gastritis. Gut 2015; 64: 1353-1367 [PMID:
26187502 DOI: 10.1136/gutjnl-2015-309252]
3#  Kodama M, Okimoto T, Ogawa R, Mizukami K, Murakami K. Endoscopic atrophic
classification before and after H. pylori eradication is closely associated with histological
atrophy and intestinal metaplasia. Endosc Int Open 2015; 3: E311-E317 [PMID: 26357676 DOI:
10.1055/s-0034-1392090]
4# Kono S,Gotoda T,Yoshida S, et al. 12  Kodama M, Okimoto T, Ogawa R, Mizukami K,
Murakami K. Endoscopic atrophic classification before and after H. pylori eradication is closely
associated with histological atrophy and intestinal metaplasia. World J Gastroenterol 2015
December 14; 21(46): 13113-13123.
Minor points
1. On page 2, line 7 of the INTRODUCTION, “Chronic atrophic gastritis (CAG) is a
precancerous disease of GC that positively correlates with GC morbidity.“  please add the
following citation.
1# Uemura N, Okamoto S, Yamamoto S et al. Helicobacter pylori infection and the development
of gastric cancer. N Engl J Med 2001; 345: 784–9.
2# Masuyama H, et al. Relationship between the degree of endoscopic atrophy of the gastric
mucosa and carcinogenic risk. Diestion.91(1):30-6, 2015
2. In order to reduce the gastric cancer mortality rate in China, it is necessary and effective to
diagnose atrophic gastritis, a gastric cancer risk, at an early stage by using AI in endoscopy
as discussed in this study, as well as by blood tests such as ABC classification combined with
antibody tests for H.pylori infection and serum PG test to see atrophy, which is the main cause
of atrophic gastritis in the first place. In the discussion, it is necessary to state that it is also
necessary and effective to consolidate the endoscopic examination, which is a limited resource.