Review for 10.1186/s12876-022-02358-y (2022)

Title: Physical activity measured by accelerometry in paediatric and young adult patients with
inflammatory bowel disease
Version: 2 Date: 18 Apr 2022
Reviewer's report:
Thank you for the opportunity to review this manuscript. The authors performed a case-series
study to objectively describe the level of physical activity in pediatric and young adult patients
with IBD as measured by tri-axial wrist accelerometers. They found a higher volume of physical
activity in males compared to females and a decrease in volume with age. No difference was
observed between CD and UC. I think this is an interesting study, but I do have some questions
and comments I would like the authors to address.
1. Regarding the title: putting ‘as measured by accelerometry’ after IBD implies that IBD is
measured by accelerometry. Consider to rewrite the title.
2. In the abstract the aim is to describe physical activity patterns, I would suggest to make this
in line with the text and replace patterns by level.
3. Participants received instructions regarding how and when to wear the accelerometer, were
they also instructed on maintaining the same level of physical activity as before? How about
reactivity bias? This is likely not present in 10 year old participants, but can definitely be present
in the 20 year old ones.
4. Table 1: I understand that results less than 5 are not allowed to be reported, but besides that I
am wondering: is it correct that not all participants reported smoking data? Since numbers don’t
add up to 100%.
5. ‘with 91.8% of participants providing at least 4 days of data’ : was a minimum number of
days per participant determined to be included in the analysis?
6. Please have a look at patients vs participants, try to be consistent
7. Overall, the manuscript is very well written. However, I recommend to read the results, figure
legends and discussion section thoroughly one more time to further improve it since sometimes
words seem to be missing and incorrect verbs are used. For example in the legend of figure 3 +
its description in the text and the sentence “The accelerometer methods are validated … volume
(ENMO) and intensity levels.”
8. Page 14: “The total average duration in the four categories … and 7 minutes (95% CI 3-10).”
Consider to present this information in a table and describe any differences in the text in analogy
with Table 2. Now it is quite a lot of numbers and more difficult to see differences.
9. Throughout the manuscript I understood that there is no significant difference between CD
and UC, but there is between males and females and an inverse association with age. However, I
think the first paragraph of the discussion is unclear about this. “However, we observed that the
… females, and older ages, respectively.” Especially this sentence doesn’t seem to be in line with
the final conclusion, also a difficult sentence to read and therefore understand, please rewrite.
10. Please be consistent with the study population description (first sentence of discussion + first
sentence of final conclusion), pediatric and young adult patients.
11. “To our knowledge, this study … is evaluated by this method.” This is a strength of the
study, please move to the corresponding section.
12. The first limitation (we included pediatric and young adult patients in remission from
multiple sites) is actually a strength and not a limitation. The “but” after this sentence is used
incorrectly, those two sentences should not be connected. Please move the first part to the
corresponding section.
13. I think the paragraph starting with “Our study did not explore the impact of …” is a very
important paragraph, but it doesn’t seem to be in the right place. I would suggest to place it
before the strengths and limitations.