Review for 10.1186/s12876-020-01538-y (2020)

Reviewer’s report
Title: 
Association between platelet count and mucosal healing in Japanese
patients with ulcerative colitis: A cross-sectional study
Version: 
1 
Date: 
28 Oct 2020
Reviewer's report:
We thank the authors for their response. However, I am not convinced that they
have sufficiently addressed my concern, and I have further queries about the
methodology of the study.
The authors point out that the main problem with previous reports was that they
were 'retrospective', insinuating that this study is different. From what I
understand, the previous reports were all also cross-sectional studies with similar
design. The "positive dose-response relationship" of platelet count and mucosal
healing has also already been described in a previous report by Uchihara et al. 
1) There is no description regarding chronology of data collection in this paper
for it to count as a cross-sectional study. When were the blood tests taken in
relation to the timing of colonoscopy? 
2) Please describe how the patients were enrolled in the study (time span of
enrollment, whether patients were selected according to a particular criterion or
not).
3) Please describe the extents of colitis in the patients.
4) In order to make a statement about positive association between platelet count
and mucosal healing, please consider plotting ROC curves and calculating the
AUC.
5) Please mention the details of usage of immunomodulators such as
azathioprine which is known to affect platelet count. 
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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?
No
Are the methods sufficiently described to allow the study to be repeated?
No
Is the use of statistics and treatment of uncertainties appropriate?
No
Is the presentation of the work clear?
Yes
Are the images in this manuscript (including electrophoretic gels and blots) free
from apparent manipulation?
Yes