Reviewer's report
Title:Diet in subjects with irritable bowel syndrome: a cross-sectional study in
the general population
Version: 1Date:30 March 2012
Reviewer: Filippo Cremonini
Reviewer's report:
Dr Ligaarden and colleagues present the results of a population-based dietary
survey, reporting on differences in dietary intake between participants whose
symptoms meet Rome II criteria for IBS and the remainder of the responders.
They are also able to report differences according to bowel pattern subtype.
My main concerns are the following
1. The limitations of cross-sectional studies particularly apply when one is trying
to figure out, as in this case, whether consumption of specific foods is associated
to the condition of interest or is the result of such condition (from voluntary
dietary changes). Most of the discussion is appropriately centered on this.
2. It would be helpful if the Authors could formulate a hypothesis and specify
pre-set comparison groups in the aims and methods sections.
3. The response rate is, not uncommonly, low. How did dietary habits compare
with prior surveys of similar or greater response rate which might have been
conducted in the same geographical area?
4. As acknowledged, the questionnaire used is not comprehensive. As I presume
a number of subjects were more closely studied given they provided blood
samples, was the information they had given in questionnaires checked in face to
face interviews to assess for internal consistency? Was there any attempt at
determining calorie intake, eating behavior patterns, actual macronutrients most
consumed?
5. By looking at the confidence intervals, for some of the associations
demonstrated (eg alcohol) these are wider. Could the Authors provide actual
number of subjects categorized in comparison groups in the tables?
Additional concerns
1. Please provide references for symptom severity calculation method and for
food questionnaire validation
2. Please clarify why only omega-3 levels were drawn, and if there were
differences in these between IBS and controls
3. As noted before, please provide raw numbers for people in all comparison
groups shown, so the reader can be aware of what contrasts were based on
smaller group of subjects
4. Are there any data here on specific vegetables consumed which could support
the claims, very reasonable per se, made in the discussion?
5. Any information on the ‘consulter’ status of those meeting Rome II criteria?
6. As the Authors report association of alcohol consumption with an IBS
subgroup, they could briefly clarify how the amount of alcohol consumed was
estimated and provide distribution of different degrees of consumption in their
sample
Level of interest: An article of importance in its field
Quality of written English: Acceptable
Statistical review: No, the manuscript does not need to be seen by a
statistician.
Declaration of competing interests:
I declare that I have no competing interests
Reviewer's report
Title:Diet in subjects with irritable bowel syndrome: a cross-sectional study in
the general population
Version: 1Date:30 March 2012
Reviewer: Filippo Cremonini
Reviewer's report:
Dr Ligaarden and colleagues present the results of a population-based dietary
survey, reporting on differences in dietary intake between participants whose
symptoms meet Rome II criteria for IBS and the remainder of the responders.
They are also able to report differences according to bowel pattern subtype.
My main concerns are the following
1. The limitations of cross-sectional studies particularly apply when one is trying
to figure out, as in this case, whether consumption of specific foods is associated
to the condition of interest or is the result of such condition (from voluntary
dietary changes). Most of the discussion is appropriately centered on this.
2. It would be helpful if the Authors could formulate a hypothesis and specify
pre-set comparison groups in the aims and methods sections.
3. The response rate is, not uncommonly, low. How did dietary habits compare
with prior surveys of similar or greater response rate which might have been
conducted in the same geographical area?
4. As acknowledged, the questionnaire used is not comprehensive. As I presume
a number of subjects were more closely studied given they provided blood
samples, was the information they had given in questionnaires checked in face to
face interviews to assess for internal consistency? Was there any attempt at
determining calorie intake, eating behavior patterns, actual macronutrients most
consumed?
5. By looking at the confidence intervals, for some of the associations
demonstrated (eg alcohol) these are wider. Could the Authors provide actual
number of subjects categorized in comparison groups in the tables?
Additional concerns
1. Please provide references for symptom severity calculation method and for
food questionnaire validation
2. Please clarify why only omega-3 levels were drawn, and if there were
differences in these between IBS and controls
3. As noted before, please provide raw numbers for people in all comparison
groups shown, so the reader can be aware of what contrasts were based on
smaller group of subjects
4. Are there any data here on specific vegetables consumed which could support
the claims, very reasonable per se, made in the discussion?
5. Any information on the ‘consulter’ status of those meeting Rome II criteria?
6. As the Authors report association of alcohol consumption with an IBS
subgroup, they could briefly clarify how the amount of alcohol consumed was
estimated and provide distribution of different degrees of consumption in their
sample
Level of interest: An article of importance in its field
Quality of written English: Acceptable
Statistical review: No, the manuscript does not need to be seen by a
statistician.
Declaration of competing interests:
I declare that I have no competing interests
Please review this paper.
user
Reviewer's report
Title:Diet in subjects with irritable bowel syndrome: a cross-sectional study in
the general population
Version: 1Date:30 March 2012
Reviewer: Filippo Cremonini
Reviewer's report:
Dr Ligaarden and colleagues present the results of a population-based dietary
survey, reporting on differences in dietary intake between participants whose
symptoms meet Rome II criteria for IBS and the remainder of the responders.
They are also able to report differences according to bowel pattern subtype.
My main concerns are the following
1. The limitations of cross-sectional studies particularly apply when one is trying
to figure out, as in this case, whether consumption of specific foods is associated
to the condition of interest or is the result of such condition (from voluntary
dietary changes). Most of the discussion is appropriately centered on this.
2. It would be helpful if the Authors could formulate a hypothesis and specify
pre-set comparison groups in the aims and methods sections.
3. The response rate is, not uncommonly, low. How did dietary habits compare
with prior surveys of similar or greater response rate which might have been
conducted in the same geographical area?
4. As acknowledged, the questionnaire used is not comprehensive. As I presume
a number of subjects were more closely studied given they provided blood
samples, was the information they had given in questionnaires checked in face to
face interviews to assess for internal consistency? Was there any attempt at
determining calorie intake, eating behavior patterns, actual macronutrients most
consumed?
5. By looking at the confidence intervals, for some of the associations
demonstrated (eg alcohol) these are wider. Could the Authors provide actual
number of subjects categorized in comparison groups in the tables?
Additional concerns
1. Please provide references for symptom severity calculation method and for
food questionnaire validation
2. Please clarify why only omega-3 levels were drawn, and if there were
differences in these between IBS and controls
3. As noted before, please provide raw numbers for people in all comparison
groups shown, so the reader can be aware of what contrasts were based on
smaller group of subjects
4. Are there any data here on specific vegetables consumed which could support
the claims, very reasonable per se, made in the discussion?
5. Any information on the ‘consulter’ status of those meeting Rome II criteria?
6. As the Authors report association of alcohol consumption with an IBS
subgroup, they could briefly clarify how the amount of alcohol consumed was
estimated and provide distribution of different degrees of consumption in their
sample
Level of interest: An article of importance in its field
Quality of written English: Acceptable
Statistical review: No, the manuscript does not need to be seen by a
statistician.
Declaration of competing interests:
I declare that I have no competing interests
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