Reviewer ’s report  
 
Title: Irritable bowel syndrome -like symptoms and health related quality of life two years after  
Roux -en-Y gastric bypass - a prospective cohort study  
 
Version: 0 Date: 24 May 2019  
 
Reviewer: Yoav Mazor  
 
Reviewer's report:  
 
I read with interest the article 'Irritable bowel syndrome and health related quality of life two 
years after Roux -en_Y gastric bypass - a prospective cohort study' by Blom -Hogestol et al. The 
authors should be applauded for their effort to assess complica tions of RYGB and their relation 
to quality of life measures. The presented cohort (n=233) with two years follow up is of 
sufficient size, with acceptable follow up rates (76%). Missing data is sometimes substantial 
(19% of patients from one of the two inc luded centers did not have baseline HRQoL), but all 
missing data is accounted for, and statistical methods are performed and reported as appropriate.  
Main findings suggested by this article are (1) 22% of patients develop IBS following RYGB (2 
years), (2)  Some predictors of developing IBS exists, especially pre -surgery IBS, (3) IBS is 
associated with reduced QOL.  
 
My main comment regards the use of the IBS Rome definition in this cohort. Rome III defines 
IBS as a symptom based diagnosis which includes abd ominal pain/discomfort, with 2 of 3 
features: (1) improvement with defecation (2) onset associated with change in stool form or (3) 
change in stool frequency, all lasting for at least 6 months. Rome IV furthers this definition to 
include only pain and not discomfort. This symptom -cluster has been validated in numerous 
studies of non -surgical patients, and minimal, if any, additional work up is required in these 
patients. Pathophysiology includes gut hyper -sensitivity.  
 
Nevertheless, applying this Rome defi nition to patients following surgery, specifically intestinal 
surgery, requires additional care. As the authors themselves show, change in bowel habits is 
common following RYGB (diarrhea and constipation scores increased significantly from 
baseline). Abdom inal pain (but not necessarily IBS) is also common following non -intestinal 
surgery (Sperber et al 2008 Gastroenterology). Furthermore, multiple non -functional etiologies 
for abdominal pain can be present following bariatric surgery (Greenstei et al, Am J Surg. 2011); 
in a previous publication from the same study group, an underlying organic explanation for 
abdominal pain was found in 34 (76% ) of patients with abdominal pain 5 years following 
bariatric surgery (Blom -Hogestol et al, Surg Obes Relat Dis. 201 8). Only 5 (17%) of these 
patients were given a diagnosis of IBS.  
 
As such, missing are the following data:  
 
1- What was the prevalence of abdominal pain before surgery and at two years? The authors cite 
a study looking at this question (ref 12, Chahal -Kum men M et al accepted for publication, not 
available online yet). What are the differences between these two studies?  
2- What was the prevalence of each of the Rome criteria (change in stool form, frequency and 
relation of pain to defecation) before and af ter surgery? How many patients were actually 
defined as IBS due to abdominal pain and change in defecation habits resulting from surgery? 
What was the prevalence of other pain -related Rome diagnosis such as central -mediated (chronic 
functional) abdominal p ain, dyspepsia or non -specific abdominal pain?  
 
3- What, if any, work up was performed for these problems (abdominal pain and change in stool 
habits)? Although no formal guidelines exists, in light of the above publications reasonable 
testing would include  exclusion of surgical complications, celiac, lactose intolerance and biliary 
colic. How many patients were tested for these alternative diagnosis?  
 
4- What medications were patients taking at follow up? Anti -pain medications can severely 
effect bowel habit s, and treating with neuromodulators (TCA, SNRI) can ameliorate IBS -like 
symptoms. Can the authors present any data on these?  
 
 
Minor comments include:  
 
1- What was the prevalence of the different subtypes of IBS?  
 
2- No discussion of the associating of high  vitamin B1 with developing of IBS/pain/change in 
bowel?  
 
 
 
Are the methods appropriate and well described?  
If not, please specify w hat 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.  
 
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 manus cript or would you recommend an 
additional statistical review?  
If an additional statistical review is recommended, please specify what aspects requir e further 
assessment 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:  
 
Acceptable  
 
 
 
Declaration of competing interests  
Please complete a declaration of competing interests, considering the following quest ions:  
 
1. Have you in the past five years received reimbursements, f ees, funding, or salary from an 
organisation that may in any way gain or lose financial ly from the publication of this 
manuscript, either now or in the future?  
 
2. Do you hold any stocks or shares in an organisation t hat 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 com peting 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 no competing interests  
 
I agree t o the open peer review policy of the journal. I understan d that my name will be included 
on my report to the authors and, if the manuscript is accepted f or 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 in cluded as confidential comments 
to the editor s, which will not be published.  
 
I agree to the open peer review policy of the journal  
Reviewer ’s report  
 
Title: Irritable bowel syndrome -like symptoms and health related quality of life two years after  
Roux -en-Y gastric bypass - a prospective cohort study  
 
Version: 0 Date: 24 May 2019  
 
Reviewer: Yoav Mazor  
 
Reviewer's report:  
 
I read with interest the article 'Irritable bowel syndrome and health related quality of life two 
years after Roux -en_Y gastric bypass - a prospective cohort study' by Blom -Hogestol et al. The 
authors should be applauded for their effort to assess complica tions of RYGB and their relation 
to quality of life measures. The presented cohort (n=233) with two years follow up is of 
sufficient size, with acceptable follow up rates (76%). Missing data is sometimes substantial 
(19% of patients from one of the two inc luded centers did not have baseline HRQoL), but all 
missing data is accounted for, and statistical methods are performed and reported as appropriate.  
Main findings suggested by this article are (1) 22% of patients develop IBS following RYGB (2 
years), (2)  Some predictors of developing IBS exists, especially pre -surgery IBS, (3) IBS is 
associated with reduced QOL.  
 
My main comment regards the use of the IBS Rome definition in this cohort. Rome III defines 
IBS as a symptom based diagnosis which includes abd ominal pain/discomfort, with 2 of 3 
features: (1) improvement with defecation (2) onset associated with change in stool form or (3) 
change in stool frequency, all lasting for at least 6 months. Rome IV furthers this definition to 
include only pain and not discomfort. This symptom -cluster has been validated in numerous 
studies of non -surgical patients, and minimal, if any, additional work up is required in these 
patients. Pathophysiology includes gut hyper -sensitivity.  
 
Nevertheless, applying this Rome defi nition to patients following surgery, specifically intestinal 
surgery, requires additional care. As the authors themselves show, change in bowel habits is 
common following RYGB (diarrhea and constipation scores increased significantly from 
baseline). Abdom inal pain (but not necessarily IBS) is also common following non -intestinal 
surgery (Sperber et al 2008 Gastroenterology). Furthermore, multiple non -functional etiologies 
for abdominal pain can be present following bariatric surgery (Greenstei et al, Am J Surg. 2011); 
in a previous publication from the same study group, an underlying organic explanation for 
abdominal pain was found in 34 (76% ) of patients with abdominal pain 5 years following 
bariatric surgery (Blom -Hogestol et al, Surg Obes Relat Dis. 201 8). Only 5 (17%) of these 
patients were given a diagnosis of IBS.  
 
As such, missing are the following data:  
 
1- What was the prevalence of abdominal pain before surgery and at two years? The authors cite 
a study looking at this question (ref 12, Chahal -Kum men M et al accepted for publication, not 
available online yet). What are the differences between these two studies?  
2- What was the prevalence of each of the Rome criteria (change in stool form, frequency and 
relation of pain to defecation) before and af ter surgery? How many patients were actually 
defined as IBS due to abdominal pain and change in defecation habits resulting from surgery? 
What was the prevalence of other pain -related Rome diagnosis such as central -mediated (chronic 
functional) abdominal p ain, dyspepsia or non -specific abdominal pain?  
 
3- What, if any, work up was performed for these problems (abdominal pain and change in stool 
habits)? Although no formal guidelines exists, in light of the above publications reasonable 
testing would include  exclusion of surgical complications, celiac, lactose intolerance and biliary 
colic. How many patients were tested for these alternative diagnosis?  
 
4- What medications were patients taking at follow up? Anti -pain medications can severely 
effect bowel habit s, and treating with neuromodulators (TCA, SNRI) can ameliorate IBS -like 
symptoms. Can the authors present any data on these?  
 
 
Minor comments include:  
 
1- What was the prevalence of the different subtypes of IBS?  
 
2- No discussion of the associating of high  vitamin B1 with developing of IBS/pain/change in 
bowel?  
 
 
 
Are the methods appropriate and well described?  
If not, please specify w hat 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.  
 
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 manus cript or would you recommend an 
additional statistical review?  
If an additional statistical review is recommended, please specify what aspects requir e further 
assessment 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:  
 
Acceptable  
 
 
 
Declaration of competing interests  
Please complete a declaration of competing interests, considering the following quest ions:  
 
1. Have you in the past five years received reimbursements, f ees, funding, or salary from an 
organisation that may in any way gain or lose financial ly from the publication of this 
manuscript, either now or in the future?  
 
2. Do you hold any stocks or shares in an organisation t hat 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 com peting 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 no competing interests  
 
I agree t o the open peer review policy of the journal. I understan d that my name will be included 
on my report to the authors and, if the manuscript is accepted f or 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 in cluded as confidential comments 
to the editor s, 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: Irritable bowel syndrome -like symptoms and health related quality of life two years after  
Roux -en-Y gastric bypass - a prospective cohort study  
 
Version: 0 Date: 24 May 2019  
 
Reviewer: Yoav Mazor  
 
Reviewer's report:  
 
I read with interest the article 'Irritable bowel syndrome and health related quality of life two 
years after Roux -en_Y gastric bypass - a prospective cohort study' by Blom -Hogestol et al. The 
authors should be applauded for their effort to assess complica tions of RYGB and their relation 
to quality of life measures. The presented cohort (n=233) with two years follow up is of 
sufficient size, with acceptable follow up rates (76%). Missing data is sometimes substantial 
(19% of patients from one of the two inc luded centers did not have baseline HRQoL), but all 
missing data is accounted for, and statistical methods are performed and reported as appropriate.  
Main findings suggested by this article are (1) 22% of patients develop IBS following RYGB (2 
years), (2)  Some predictors of developing IBS exists, especially pre -surgery IBS, (3) IBS is 
associated with reduced QOL.  
 
My main comment regards the use of the IBS Rome definition in this cohort. Rome III defines 
IBS as a symptom based diagnosis which includes abd ominal pain/discomfort, with 2 of 3 
features: (1) improvement with defecation (2) onset associated with change in stool form or (3) 
change in stool frequency, all lasting for at least 6 months. Rome IV furthers this definition to 
include only pain and not discomfort. This symptom -cluster has been validated in numerous 
studies of non -surgical patients, and minimal, if any, additional work up is required in these 
patients. Pathophysiology includes gut hyper -sensitivity.  
 
Nevertheless, applying this Rome defi nition to patients following surgery, specifically intestinal 
surgery, requires additional care. As the authors themselves show, change in bowel habits is 
common following RYGB (diarrhea and constipation scores increased significantly from 
baseline). Abdom inal pain (but not necessarily IBS) is also common following non -intestinal 
surgery (Sperber et al 2008 Gastroenterology). Furthermore, multiple non -functional etiologies 
for abdominal pain can be present following bariatric surgery (Greenstei et al, Am J Surg. 2011); 
in a previous publication from the same study group, an underlying organic explanation for 
abdominal pain was found in 34 (76% ) of patients with abdominal pain 5 years following 
bariatric surgery (Blom -Hogestol et al, Surg Obes Relat Dis. 201 8). Only 5 (17%) of these 
patients were given a diagnosis of IBS.  
 
As such, missing are the following data:  
 
1- What was the prevalence of abdominal pain before surgery and at two years? The authors cite 
a study looking at this question (ref 12, Chahal -Kum men M et al accepted for publication, not 
available online yet). What are the differences between these two studies?  
2- What was the prevalence of each of the Rome criteria (change in stool form, frequency and 
relation of pain to defecation) before and af ter surgery? How many patients were actually 
defined as IBS due to abdominal pain and change in defecation habits resulting from surgery? 
What was the prevalence of other pain -related Rome diagnosis such as central -mediated (chronic 
functional) abdominal p ain, dyspepsia or non -specific abdominal pain?  
 
3- What, if any, work up was performed for these problems (abdominal pain and change in stool 
habits)? Although no formal guidelines exists, in light of the above publications reasonable 
testing would include  exclusion of surgical complications, celiac, lactose intolerance and biliary 
colic. How many patients were tested for these alternative diagnosis?  
 
4- What medications were patients taking at follow up? Anti -pain medications can severely 
effect bowel habit s, and treating with neuromodulators (TCA, SNRI) can ameliorate IBS -like 
symptoms. Can the authors present any data on these?  
 
 
Minor comments include:  
 
1- What was the prevalence of the different subtypes of IBS?  
 
2- No discussion of the associating of high  vitamin B1 with developing of IBS/pain/change in 
bowel?  
 
 
 
Are the methods appropriate and well described?  
If not, please specify w hat 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.  
 
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 manus cript or would you recommend an 
additional statistical review?  
If an additional statistical review is recommended, please specify what aspects requir e further 
assessment 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:  
 
Acceptable  
 
 
 
Declaration of competing interests  
Please complete a declaration of competing interests, considering the following quest ions:  
 
1. Have you in the past five years received reimbursements, f ees, funding, or salary from an 
organisation that may in any way gain or lose financial ly from the publication of this 
manuscript, either now or in the future?  
 
2. Do you hold any stocks or shares in an organisation t hat 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 com peting 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 no competing interests  
 
I agree t o the open peer review policy of the journal. I understan d that my name will be included 
on my report to the authors and, if the manuscript is accepted f or 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 in cluded as confidential comments 
to the editor s, which will not be published.  
 
I agree to the open peer review policy of the journal  
assistant