Review for 10.1186/s12876-020-01597-1 (2021)

Reviewer’s report
Title: 
Prevalence and risk factors of bowel symptoms in Korean patients with
ulcerative colitis in endoscopic remission: a retrospective study
Version: 
0 
Date: 
14 Oct 2020
Reviewer's report:
The study entitled "Prevalence and risk factors of bowel symptoms in Korean
patients with ulcerative colitis in endoscopic remission: a retrospective study"
included 741 subjects with endoscopically quiescent ulcerative colitis (UC)
referring to the Asan IBD center and investigated the presence of symptoms
(stool frequency and rectal bleeding), which were found in approximately one
third of patients despite endoscopic Mayo score of 0 at recent endoscopy. At
multivariate analysis, female sex and left-sided or extensive colitis were
identified as risk factors associated with bowel symptoms. 
Data on this topic in Korean patients are scarce. Moreover, this study is well
conducted and clearly written. 
There are few points that need to be addressed before publication. 
1. It is not clear whether immunosuppressive therapies were given in the past or
simultaneously at clinical evaluation. If given historically, that should be clearly
stated in the methods and in the table 1 ("history of immunosuppressive
therapies" or "concomitant imm therapy"). 
2. Line 151, sentence "in case of multiple endoscopic evaluation, most recent
examination was selected for the evaluation". Do you mean the most recent
quiescent endoscopy? Or all quiescent endoscopies were selected from the most
recent procedures of all UC patients? Please, clarify. 
3. The interval between the date of endoscopy and the evaluation visit is short
(median 8 days, IQR 6.5-15), but it is not specified it the visits were performed
before or after endoscopy. This information is important because there are some
reports of clinical relapse of UC after endoscopic procedures (for example,
Menees et al. IBD 2007). If it is not possible to retrieve these data, a comment
should be added in the discussion, among other study limitations.
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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?
Yes
Are the methods sufficiently described to allow the study to be repeated?
Yes
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Yes
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Yes
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from apparent manipulation?
Yes