Review for 10.1186/s12876-021-02003-0 (2021)

Title: The physiological and psychological effects of cognitive behavior therapy on patients
with inflammatory bowel disease before COVID-19: a systematic review
Version: 1 Date: 03 Sep 2021
Reviewer:  Ravi Philip Rajkumar
Reviewer's report:
This paper is a systematic review of the physiological and psychological effects of cognitive
behavioural therapy (CBT) in patients with inflammatory bowel disease.
While the paper is largely methodologically sound and well-organized, I have certain concerns
regarding the following aspects of this work:
1. As mentioned above, there are already two systematic reviews / meta-analyses covering this
topic (published in 2017 and 2019). The authors need to provide a clear justification for why a
new systematic review is needed: have significant new studies have been published since 2019?
Does the current review contains methodological or statistical refinements? Does this review
measure outcomes that were ignored by the earlier reviews?
2. The treatment of the physical and psychological consequences of IBD is superficial. More
information should be presented about the frequency of anxiety and depression in these
disorders, issues related to body image or self-esteem (for example, due to weight loss, dietary
restriction or the need for a colostomy), and the domains of quality of life that are impaired by
this group of disorders.
3. The authors seem confused about the aim of CBT and related therapies in IBD. They
are not intended as primary or disease-modifying treatments; rather, they aim to target the
psychological, behavioural and social factors flagged in #2 above. Hence, statements such as
"CBT is not effective in IBD" should be rewritten in a more accurate manner.
4. The title refers to CBT, but in section 2.1.3 it is mentioned that a broader range of interventions
which the authors considered to be "a form of CBT" have been included. It is not clear if ACT
and mindfulness (the examples given by the authors) can be considered simply "forms of CBT"
as they incorporate distinct principles and techniques outside the CBT paradigm. As a re-review
may not be feasible at this stage, I suggest that the authors modify their title to reflect the
heterogeneity of the studies included in their review.
5. Information on assessment of publication bias and the quality of individual studies has not
been provided in the text, though they are mentioned in the PRISMA checklist. If these have
been done and included in the supplementary material, the authors should mention it; if not, they
should add this information, or mention its omission as a significant limitation.
6. Subheadings, such as (a) and (b), may be provided before "Crohn's disease activity" and
"Ulcerative colitis activity" under the broad heading "Disease activity". C-reactive protein
changes can also be included under this heading, as they are a measure of disease activity.
Given the authors' title, it may be useful to use two broad headings (Psychological and
Physiological) - the former would include anxiety, depression, stress and QoL, while the latter
would include disease activity (UC and Crohn's) and inflammatory markers such as CRP. This
would significantly enhance the readability and clarity of the paper.
7. In section 3.5, the authors have consistently used the given names of the first authors, instead
of their surnames, to refer to individual studies. Please correct this for the sake of style (for
example, a paper by "Melissa G. Hunt et al." should be referred to as "Hunt et al.", not "Melissa
et al.", as per Western naming conventions.)
8. The mention of IBS on page 13 is not particularly relevant to the current study. While there
are some authors who argue for a role of inflammation in IBS, this is far from an established
or confirmed hypothesis. It would be preferable to omit this, as the current review's focus is on
IBD (UC / Crohn's).
9. Limitations need to be explored in more depth, including the points raised above (if no
justification is provided) as well as any methodological flaws the authors have identified in
individual studies (such as a lack of uniform outcome measures).