Review for 10.1186/s12876-020-01478-7 (2020)

Reviewer’ s report
Title: Classification of Gastrointestinal Symptom Patterns in Young Adults
Version: 1Date: 04 May 2020
Reviewer's report:This is an interesting study on gastrointestinal symptoms surveyed among college students
attending a psychology course.
The following issues need to be addressed-
Background
1.Paragraph 1- In describing what 'FGID' encompasses, suggest to reword so as to be specific inwhether this is referring to disease categories or etiological mechanisms.
2.A general comment on the literature review is that it lacked specifically describing the
prevalence figures for ROME-defined FGIDs according to the respective criteria. This should bedifferent, and explicated as such, from studies that only reported frequency of functional GIsymptoms as per the ROME categories but which did not consider the duration criteria- whichshould have onset at least 6 months prior to diagnosis, with current persistence for more than 3months. There should also be a separate consideration/ description of prevalence figures yieldedfrom different samples - eg. Randomly sampled from the general population, college samples andclinic samples.
Enrolment
The limitations of recruiting only from psychology major should be explicated in the discussion
section, especially on how it may affect the results
Assessment/outcomes
1. PROMIS-GI is a trans-diagnostic instrument for measuring gastrointestinal symptoms across allorganic and functional GI illnesses. It would have included upper and lower GI symptoms butplease explicate how the data were captured or analyzed to yield real ROME IV categories, whichwould require duration criteria for at least 3 months of symptoms, onset 6 months prior todiagnosis. Therefore, it is also recommended that throughout the manuscript, the authors bespecific in referring to whether this paper describes GI symptom dimensions or specific ROMEFGID categories. From the way the data is presented, it is more compatible with the former andlacks justification for the latter. It is important to note that , although most FGI symptoms arechronic and may constitute a large part of the current dataset, a substantial subset may be sufferingfrom non-FGID or organic conditions ( infectious, ulcers, etc).
2. It is inappropriate to avoid SF-36 mental health summary outcome score - SF-36 is a measure
of health-related functional impairment, whereas GAD 7and PHQ9 reflects clinical severity ofgeneralized anxiety disorder and depression. It is of particular interest, in examination ofpsychosomatic data (eg. Where patients present with both mood and physical symptoms) how
physical and mood symptoms respectively will be differentially associated with functional
impairment in terms of physical component summary and mental component summary. In some
datasets, one might see elevated mood symptom scores but not the SF36 mental componentsummary, whereas it is the physical component summary that is elevated and is associated with thesomatic symptoms. Including these data would also be important for comparison between studies.
Results/discussion
1.As a basic requirement in epidemiological research, the size of the total target sample and finalsample, and the response rate must be clearly stated. Differences in demographic data betweentarget and final respondent sample must be clearly stated. Prevalence data should also be weighted
according to sex and age composition of the final respondent sample and those of the target
sample. Unless this has been done, the analysis needs to be repeated.2.In examining data trends in figure 3 - an interesting difference between 'normal' and the other 2classes is the lower score of belly pain in class 1. Please discuss its significance. Otherwise thetrends across the 3 classes are the same. And as such the data did not in anyway confirm Romecategories. It is an antithesis. Please discuss accordingly in light of any data in the literature ofprevalence studies in upper/lower GI overlaps. In fact - how 'dimensional' is ROME?3.There should also be substantial literature to cite regarding how somatic symptoms andfunctional gi symptoms severity specifically would be in parallel with mood/anxiety and alsoreflect general illness severity.4.In light of the comments (Background - 1) it would then be possible to address how this study onemerging adults may contrast with those reported in the literature. It is unclear as it stands now.
Are the methods appropriate and well described?
If not, please specify what is required in your comments to the authors.
No
Does the work include the necessary controls?
If not, please specify which controls are required in your comments to the authors.
Unable to assessAre the conclusions drawn adequately supported by the data shown?
If not, please explain in your comments to the authors.
YesAre you able to assess any statistics in the manuscript or would you recommend an
additional statistical review?If an additional statistical review is recommended, please specify what aspects require furtherassessment in your comments to the editors.
I am able to assess the statistics
Quality of written English
Please indicate the quality of language in the manuscript:
AcceptableDeclaration of competing interests
Please complete a declaration of competing interests, considering the following questions:
1. Have you in the past five years received reimbursements, fees, funding, or salary from an
organisation that may in any way gain or lose financially from the publication of this
manuscript, either now or in the future?
2. Do you hold any stocks or shares in an organisation that may in any way gain or lose
financially from the publication of this manuscript, either now or in the future?
3. Do you hold or are you currently applying for any patents relating to the content of the
manuscript?
4. Have you received reimbursements, fees, funding, or salary from an organization that holds
or has applied for patents relating to the content of the manuscript?
5. Do you have any other financial competing interests?6. Do you have any non-financial competing interests in relation to this paper?
If you can answer no to all of the above, write 'I declare that I have no competing interests' below.
If your reply is yes to any, please give details below.
Nil to all.
Reviewer Publication Consent. I agree for my report to be made available under an Open Access
Creative Commons CC-BY License (http://creativecommons.org/licenses/by/4.0) if this manu-script is accepted for publication. Any comments that I do not wish to be included in the publishedreport have been included as confidential comments to the editor, which will not be published.Ifyou are not happy for us to publish this report, please contact the editorial office before completingthe review.If you wish, you can include your name in your published report. Please note you mustdecide whether to include your name at the start of the process and confirm this decision wheneverprompted. If you change your decision later, we will not be able to publish your name.
I agree to the terms of the CC-BY 4.0 license; please publish my name with my report.