Reviewer ’s report  
 
Title: Smoking Influences the Need for Surgery in Patients  with the Inflammatory Bowel  
Diseases: a Systematic Review and Meta -Analysis Incorporating Disease Duration  
 
Version: 0 Date: 24 Jul 2016  
 
Reviewer: Fernando Veloso  
 
Reviewer's report:  
 
In this systematic review and meta -analysis the authors examined the association between 
smoking status and time to first bowel resection in patient s with Crohn's disease and ulcerative 
colitis.  
 
 
 
 
Comments:  
 
 
1- The aim of the study is to study the association between smoking and time to surgery. So, 
it would be interesting to know that association at time of diagnosis and in the early and 
late course o f the diseases.  
 
 
2- In patients with ulcerative colitis, the authors conclude that current smokers were not at 
increased risk of colectomy. However, it would be interesting to know if there is a 
significantly lower risk of colectomy in smoking patients.  
 
 
3- There are several important limitations in this study concerning additional potential risk 
factors for surgery, mainly age at onset of disease, location of disease, and behaviour.  
 
 
 
 
Correction:  
Page 23, reference 21 and 29 in the bibliography: missing jo urnal name, and pages, respectively.  
 
 
 
 
 
 
 
Are the methods appropriate  and well described?  
If not, please specify what is required in your comments to the authors.  
 
Yes 
 
Does the work include the necessary controls?  
If not, please specify which controls are required in your comments to the authors.  
 
Unable to assess  
 
Are the conclusions draw n adequately supported by the data shown?  
If not, please explain in your comments to the authors.  
 
Unable to assess  
 
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 publi cation 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 curr ently 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 rep ort 
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 a n Open Access Creative Commons  
CC-BY license ( http://creativecommons.org/licenses/by/4.0/ ). I understa nd 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: Smoking Influences the Need for Surgery in Patients  with the Inflammatory Bowel  
Diseases: a Systematic Review and Meta -Analysis Incorporating Disease Duration  
 
Version: 0 Date: 24 Jul 2016  
 
Reviewer: Fernando Veloso  
 
Reviewer's report:  
 
In this systematic review and meta -analysis the authors examined the association between 
smoking status and time to first bowel resection in patient s with Crohn's disease and ulcerative 
colitis.  
 
 
 
 
Comments:  
 
 
1- The aim of the study is to study the association between smoking and time to surgery. So, 
it would be interesting to know that association at time of diagnosis and in the early and 
late course o f the diseases.  
 
 
2- In patients with ulcerative colitis, the authors conclude that current smokers were not at 
increased risk of colectomy. However, it would be interesting to know if there is a 
significantly lower risk of colectomy in smoking patients.  
 
 
3- There are several important limitations in this study concerning additional potential risk 
factors for surgery, mainly age at onset of disease, location of disease, and behaviour.  
 
 
 
 
Correction:  
Page 23, reference 21 and 29 in the bibliography: missing jo urnal name, and pages, respectively.  
 
 
 
 
 
 
 
Are the methods appropriate  and well described?  
If not, please specify what is required in your comments to the authors.  
 
Yes 
 
Does the work include the necessary controls?  
If not, please specify which controls are required in your comments to the authors.  
 
Unable to assess  
 
Are the conclusions draw n adequately supported by the data shown?  
If not, please explain in your comments to the authors.  
 
Unable to assess  
 
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 publi cation 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 curr ently 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 rep ort 
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 a n Open Access Creative Commons  
CC-BY license ( http://creativecommons.org/licenses/by/4.0/ ). I understa nd 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: Smoking Influences the Need for Surgery in Patients  with the Inflammatory Bowel  
Diseases: a Systematic Review and Meta -Analysis Incorporating Disease Duration  
 
Version: 0 Date: 24 Jul 2016  
 
Reviewer: Fernando Veloso  
 
Reviewer's report:  
 
In this systematic review and meta -analysis the authors examined the association between 
smoking status and time to first bowel resection in patient s with Crohn's disease and ulcerative 
colitis.  
 
 
 
 
Comments:  
 
 
1- The aim of the study is to study the association between smoking and time to surgery. So, 
it would be interesting to know that association at time of diagnosis and in the early and 
late course o f the diseases.  
 
 
2- In patients with ulcerative colitis, the authors conclude that current smokers were not at 
increased risk of colectomy. However, it would be interesting to know if there is a 
significantly lower risk of colectomy in smoking patients.  
 
 
3- There are several important limitations in this study concerning additional potential risk 
factors for surgery, mainly age at onset of disease, location of disease, and behaviour.  
 
 
 
 
Correction:  
Page 23, reference 21 and 29 in the bibliography: missing jo urnal name, and pages, respectively.  
 
 
 
 
 
 
 
Are the methods appropriate  and well described?  
If not, please specify what is required in your comments to the authors.  
 
Yes 
 
Does the work include the necessary controls?  
If not, please specify which controls are required in your comments to the authors.  
 
Unable to assess  
 
Are the conclusions draw n adequately supported by the data shown?  
If not, please explain in your comments to the authors.  
 
Unable to assess  
 
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 publi cation 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 curr ently 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 rep ort 
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 a n Open Access Creative Commons  
CC-BY license ( http://creativecommons.org/licenses/by/4.0/ ). I understa nd 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