Reviewer’s report
Title: The influence of demographic characteristics on constipation symptoms: A detailed overview
Version: 0 Date: 15 Feb 2019
Reviewer: Paola Iovino
Reviewer's report:
In these paper Authors aimed to determine the specific patterns of constipation symptoms in different
demographic groups in a large population examining whether a more individual diagnostic approach
could  be  achieved.  Secondly,  they  aimed  to  define  the  symptoms  that  best  indicate  functional
constipation by investigating a wide range of constipation symptoms. 
They concluded that sex and age independently influence the likelihood of constipation in the general
Dutch population. There are different subtypes of constipation dependent on age.
This study is certainly important. However, given the explorative nature, observational research are
powered to detect small differences in the endpoint of interest and to allow for extensive adjustment for
confounding, performing subgroup analyses and to evaluate the contribution of several independent
variables to the variance in the outcome distribution. An important corollary of such considerations is
that the evaluation of clinical significance is always a key step for interpreting results in the field of
survey research. In fact, trusting solely on p-values is a common mistake and authors should be clear in
avoiding misleading conclusions from large observational studies. 
For example, I am wondering whether the inclusion of abdominal pain, could explain the result of a
higher prevalence of all constipation symptoms in the 18 to 38-year-olds. Specifically, in accordance
with the Rome IV criteria, abdominal pain may be present but are not a predominant symptoms.
Moreover, patients with FC should not meet IBS criteria. How did you assess the presence (intensity-
frequency) of abdominal pain? 
Moreover, details of the comorbidities which were assessed should be clearer : why did you  exclude
slow transit constipation and how were these patients diagnosed? 
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.
Yes
Are the conclusions drawn adequately supported by the data shown?
If not, please explain in your comments to the authors.
No
Are 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  further
assessment in your comments to the editors.
I recommend additional statistical review
Quality of written English
Please indicate the quality of language in the manuscript:
Acceptable
Declaration 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.
I declare that I have no competing interests
I agree to the open peer review policy of the journal. I understand that my name will be included on my
report to the authors and, if the manuscript is accepted for publication, my named report including any 
attachments I upload will be posted on the website along with the authors' responses. 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/ ). I understand that any comments which I do not wish to 
be included in my named report can be included as confidential comments to the editors, which will not
be published.
I agree to the open peer review policy of the journal
Reviewer’s report
Title: The influence of demographic characteristics on constipation symptoms: A detailed overview
Version: 0 Date: 15 Feb 2019
Reviewer: Paola Iovino
Reviewer's report:
In these paper Authors aimed to determine the specific patterns of constipation symptoms in different
demographic groups in a large population examining whether a more individual diagnostic approach
could  be  achieved.  Secondly,  they  aimed  to  define  the  symptoms  that  best  indicate  functional
constipation by investigating a wide range of constipation symptoms. 
They concluded that sex and age independently influence the likelihood of constipation in the general
Dutch population. There are different subtypes of constipation dependent on age.
This study is certainly important. However, given the explorative nature, observational research are
powered to detect small differences in the endpoint of interest and to allow for extensive adjustment for
confounding, performing subgroup analyses and to evaluate the contribution of several independent
variables to the variance in the outcome distribution. An important corollary of such considerations is
that the evaluation of clinical significance is always a key step for interpreting results in the field of
survey research. In fact, trusting solely on p-values is a common mistake and authors should be clear in
avoiding misleading conclusions from large observational studies. 
For example, I am wondering whether the inclusion of abdominal pain, could explain the result of a
higher prevalence of all constipation symptoms in the 18 to 38-year-olds. Specifically, in accordance
with the Rome IV criteria, abdominal pain may be present but are not a predominant symptoms.
Moreover, patients with FC should not meet IBS criteria. How did you assess the presence (intensity-
frequency) of abdominal pain? 
Moreover, details of the comorbidities which were assessed should be clearer : why did you  exclude
slow transit constipation and how were these patients diagnosed? 
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.
Yes
Are the conclusions drawn adequately supported by the data shown?
If not, please explain in your comments to the authors.
No
Are 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  further
assessment in your comments to the editors.
I recommend additional statistical review
Quality of written English
Please indicate the quality of language in the manuscript:
Acceptable
Declaration 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.
I declare that I have no competing interests
I agree to the open peer review policy of the journal. I understand that my name will be included on my
report to the authors and, if the manuscript is accepted for publication, my named report including any 
attachments I upload will be posted on the website along with the authors' responses. 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/ ). I understand that any comments which I do not wish to 
be included in my named report can be included as confidential comments to the editors, which will not
be published.
I agree to the open peer review policy of the journal
Please review this paper.
user
Reviewer’s report
Title: The influence of demographic characteristics on constipation symptoms: A detailed overview
Version: 0 Date: 15 Feb 2019
Reviewer: Paola Iovino
Reviewer's report:
In these paper Authors aimed to determine the specific patterns of constipation symptoms in different
demographic groups in a large population examining whether a more individual diagnostic approach
could  be  achieved.  Secondly,  they  aimed  to  define  the  symptoms  that  best  indicate  functional
constipation by investigating a wide range of constipation symptoms. 
They concluded that sex and age independently influence the likelihood of constipation in the general
Dutch population. There are different subtypes of constipation dependent on age.
This study is certainly important. However, given the explorative nature, observational research are
powered to detect small differences in the endpoint of interest and to allow for extensive adjustment for
confounding, performing subgroup analyses and to evaluate the contribution of several independent
variables to the variance in the outcome distribution. An important corollary of such considerations is
that the evaluation of clinical significance is always a key step for interpreting results in the field of
survey research. In fact, trusting solely on p-values is a common mistake and authors should be clear in
avoiding misleading conclusions from large observational studies. 
For example, I am wondering whether the inclusion of abdominal pain, could explain the result of a
higher prevalence of all constipation symptoms in the 18 to 38-year-olds. Specifically, in accordance
with the Rome IV criteria, abdominal pain may be present but are not a predominant symptoms.
Moreover, patients with FC should not meet IBS criteria. How did you assess the presence (intensity-
frequency) of abdominal pain? 
Moreover, details of the comorbidities which were assessed should be clearer : why did you  exclude
slow transit constipation and how were these patients diagnosed? 
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.
Yes
Are the conclusions drawn adequately supported by the data shown?
If not, please explain in your comments to the authors.
No
Are 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  further
assessment in your comments to the editors.
I recommend additional statistical review
Quality of written English
Please indicate the quality of language in the manuscript:
Acceptable
Declaration 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.
I declare that I have no competing interests
I agree to the open peer review policy of the journal. I understand that my name will be included on my
report to the authors and, if the manuscript is accepted for publication, my named report including any 
attachments I upload will be posted on the website along with the authors' responses. 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/ ). I understand that any comments which I do not wish to 
be included in my named report can be included as confidential comments to the editors, which will not
be published.
I agree to the open peer review policy of the journal
assistant