Review for 10.1186/s12876-022-02438-z (2022)

Reviewer’s report
Title: 
Nonsteroidal anti-inflammatory drug exposure and the risk of microscopic colitis
Version: 
1 
Date: 
18 May 2022
Reviewer's report:
BMGE-D-22-00028R1
This is a case-control study including 80 MC and 123 non-MC patients with chronic diarrhoea to further
assess the association between medication usage and MC. Authors show that AAS and other NSAID
consumption increase the risk, whereas angiotensin II receptor antagonists decrease the risk of MC. No
association was found for PPIs, SSRI, and other drugs.
I have some comments to be addressed:
1. In the non-MC group, 5 IBD patients (4 ulcerative colitis and 1 Crohn's disease) were included. These
patients should be excluded, following the exclusion criteria of the study.
2. The daily stool number, faecal consistency, and duration of diarrhoea should be described as a form to
evaluate diarrhoea severity in both groups of patients, and if statistically different, logistic regression
should be performed adjusting for that.
3. Type of NSAIDs other than aspirin used should be described and compared between groups, since
different patterns of inhibition of isoforms of COX (COX-1 and COX-2) have been described depending
on the type of NSAID used. This may help to understand the differences between studies showing or not an
association between NSAID usage and MC. This should be commented in the discussion.
4. Type of PPIs used should also be described, since the association with MC seems to be higher with
lansoprazole usage than with other PPIs. This would explain the differences between studies and should be
mentioned in the discussion.
5. Subtype statistical analysis was performed to see if there were differences between the new and the
registered MC cohorts. However, there was not performed to see if there were differences between the two
forms of MC: CC and LC. It will be interesting to add these data. 
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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
Is the use of statistics and treatment of uncertainties appropriate?
Yes
Is the presentation of the work clear?
Yes
Are the images in this manuscript (including electrophoretic gels and blots) free from apparent
manipulation?
Yes