Review for 10.1186/s12876-021-01938-8 (2021)

Title: Impact of Diagnostic Delay to the Clinical Presentation and Associated Factors in
Pediatric Inflammatory Bowel Disease: A Retrospective Study
Version: 2 Date: 29 Mar 2021
Reviewer's report:
This is an interesting and well-performed study, however, I suggest to the authors some minor
revisions.
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Page 3 lines 64-67:
1) Please, explicitly declare your aim.
2) Which kind of patient records have you used? Electonic or chart medical records? Please,
specify.
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Pages 3-4 lines 70-79:
1) The study design (i.e. retrospective observational) was not clearly reported both in this
paragraph and in the abstract. Please, provide it.
2) Please, note that no information on the study period was reported. Please, specify the inclusion
period and the follow-up period (i.e. date or year).
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Page 4 line 79:
Please, complete information as suggested by adding to the end of the sentence ".... described
below, thus the IBD diagnosis date represented the index date.".
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Pages 4-5 lines 85-104:
It is not clear in which period you detected these variables. It is important to specify this.
Are symptoms and laboratory parameters retrieved in the period before the index date, i.e. the
lookback period? Are complications detected in the follow-up period?
How long are the look-back period and the follow-up?
Please, complete this information and specify the related dates.
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Page 5 lines 107-108:
Please, specify the date of the study period (the study period is made up of the look-back period
plus the inclusion period plus the follow-up period).
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Page 6 lines 127-133:
This is not the data analysis but the definition of variables of outcomes. It would be useful
to create a separate paragraph. Please, add a separate subheading before ”statistics” entitle
"definitions" and move these lines (i.e. 127-133 "Diagnostic delay was defined...") in it.
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Page 6 lines 131-133:
1) You defined the period <6months as a diagnostic delay but note that this could be an in-
time diagnosis since a plausible time period is required to make investigations driving to IBD
diagnosis. I suggest considering this and revise the concept.
In line with this, you use the period of <6months as a reference in the estimation of the odds
ratio, that is correct.
2) In addition, what do you mean for a diagnostic delay >/= 6 months? A period ranging between
>/= 6 months and #11 months, please specify it and check in the whole manuscript and tables.
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Page 6 lines 136-137:
Please, insert the following information: ”The period of <6months represented the reference”.
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Page 7 line 145:
Please, change "girls" into "females", also in table 1.
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Page 7 lines 151-152:
I am not sure that what you see as UC diagnostic delay is a delay, consider that this could be
classified as an in-time diagnosis owing to the time needed by performing diagnostic procedures.
Please, revise this concept in the whole paper in line with that also suggested for the method
section.
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Page 7 line 162:
Please, change the sentence "whereas bloody stools increased the likelihood of a delay < 6
months" into "whereas bloody stools increased the likelihood of a delay <11 months".
Note that as you reported in Table 3, there is a protective effect in a long delay (>12 months).
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Page 7 lines 162-163:
Please, change "in separate analysis" into "in a stratified analysis".
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Page 7 lines 163-164:
It would be better to specify the findings. I suggest a possible change "abdominal pain was
significantly associated with a delay >6months in UC patients and bloody stools with an in-time
diagnosis (<6 months) in CD patients.".
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Page 8 lines 180-181:
It could be also that differences in study design and methods could have affected findings, please
include this concept.
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Page 8 lines 182-183:
This is interesting information because it quantifies the delay dues to patients (the time occurred
from first symptoms to referral to hospital), please consider this concept in the paper.
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Page 8 lines 193-194:
In line with the previous comments, it could be possible that a diagnosis within 6 months as you
observed in CD patients could be an in-time diagnosis.
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Page 10 lines 225-232:
Among limitations, please add "The recall-bias could have had affected our findings of the delay
before referral to the tertiary center".
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Finally, after acquiring the minor revisions in the main paper, please check the abstract
accordingly.