Review for 10.1186/s12876-021-01604-z (2021)

Reviewer’s report
Title: 
Clinical experiences and predictors of success of treatment with
vedolizumab in IBD patients: a cohort study
Version: 
1 
Date: 
22 Dec 2020
Reviewer's report:
In this study the Authors reported a retrospective analysis on IBD patients
treated with Vedolizumab at a tertiary referral center. Real-life studies are
necessary to improve our knowledge in clinical practice. Moreover, we agree
with the Authors that finding reliable predictors of response in IBD patients
treated with remains a key unmet need. 
Despite the interesting topic of this study, however several limitations at a study
design level significantly reduce the overall quality of the study. 
The main aspects of concern are discussed below. 
1. Patient selection is unclear. The authors reported the enrollment of 181
patients (were patients consecutive?) within a long period of time (June 2014-
May 2020). Considering the heterogeneity of baseline diseases and disease stage
across the same cohort, in light of the relatively small sample size, there is high
risk that the study is underpowered to answer the clinical answer. For the same
reason, the generalizability of the findings appears limited. Finally, there is high
risk of selection bias and confounding due to the retrospective nature of the
study. 
2. Patient's characteristics pre and during treatment are unclear. "Most patients
received intensified treatment". What does it mean? Was it because of lack of
response? Moreover, concomitant therapies are not specified: were the patient
under other medications such as immunosuppressants? How many anti-TNF
were used before and why were they stopped? It is different to include patients
after failure or after interruption due to adverse events (e.g. allergic reaction). 
3. Outcomes were assessed at 17 weeks, and further follow-up is unavailable for
the majority of patients. 
4. Concerning the statistical analysis, the small sample size of each cohort
considered in the study (UC and CD) are limited to perform a meaningful
multivariable analysis. 
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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
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No
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Yes
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from apparent manipulation?
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