Reviewer's report 
 Migraine, Fibromyalgia, and Depression Among People With IBS: A Prevalence Study Title: 
 1  17 June 2006 Version: Date: 
 Giorgio Bedogni Reviewer: 
Reviewer's report: 
General 
As a statistical referee, I was asked to answer the question whether the prevalence odds ratio (POR) is an 
effect measure appropriate for the study of Cole and colleagues. 
I did not read the reviews made by the other 2 referees but I suppose that this request was made because 
POR has been criticized in recent years (mainly) on the basis that that when a disease is common, POR may differ from the prevalence rate (PR). 
However, the fact that POR and PR may differ does not tell us which measure is more appropriate to use. 
This will depend from the study context. 
In prevalence case-control studies, such as that of Cole and colleagues, POR may be considered the 
standard effect measure. 
Thus, I believe that the choice of POR as effect measure for this study is appropriate. 
------------------------------------------------------------------------------- 
Major Compulsory Revisions (that the author must respond to before a decision on publication can be reached) 
None 
------------------------------------------------------------------------------- 
Minor Essential Revisions (such as missing labels on figures, or the wrong use of a term, which the author 
can be trusted to correct) 
IN MANY PLACES 
â€œAn higher prevalence / odds ofâ € is better than â €œan increase in the prevalence / odds ofâ €. 
ABSTRACT 
â€œnon-asthmaâ € is â €œnon-IBSâ € 
BACKGROUND 
â€œRome II criteriaâ €, not â €œRome criteriaâ €. 
METHODS 
Could the choice of a National Insurance Plan as the study population have influenced the generalizability 
of the findings ? 
The Authors should cite some literature supporting the idea that a measure of cost is an acceptable 
surrogate measure of disease severity. 
------------------------------------------------------------------------------- 
Discretionary Revisions (which the author can choose to ignore) 
Speaking of causality, the Authors may wish to discuss the limitations of observational studies in detecting 
cause-effect relationships. 
 Accept after minor essential revisions What next?: 
 An article of importance in its field Level of interest: 
 Acceptable Quality of written English: 
 No Statistical review: 
Reviewer's report 
 Migraine, Fibromyalgia, and Depression Among People With IBS: A Prevalence Study Title: 
 1  17 June 2006 Version: Date: 
 Giorgio Bedogni Reviewer: 
Reviewer's report: 
General 
As a statistical referee, I was asked to answer the question whether the prevalence odds ratio (POR) is an 
effect measure appropriate for the study of Cole and colleagues. 
I did not read the reviews made by the other 2 referees but I suppose that this request was made because 
POR has been criticized in recent years (mainly) on the basis that that when a disease is common, POR may differ from the prevalence rate (PR). 
However, the fact that POR and PR may differ does not tell us which measure is more appropriate to use. 
This will depend from the study context. 
In prevalence case-control studies, such as that of Cole and colleagues, POR may be considered the 
standard effect measure. 
Thus, I believe that the choice of POR as effect measure for this study is appropriate. 
------------------------------------------------------------------------------- 
Major Compulsory Revisions (that the author must respond to before a decision on publication can be reached) 
None 
------------------------------------------------------------------------------- 
Minor Essential Revisions (such as missing labels on figures, or the wrong use of a term, which the author 
can be trusted to correct) 
IN MANY PLACES 
â€œAn higher prevalence / odds ofâ € is better than â €œan increase in the prevalence / odds ofâ €. 
ABSTRACT 
â€œnon-asthmaâ € is â €œnon-IBSâ € 
BACKGROUND 
â€œRome II criteriaâ €, not â €œRome criteriaâ €. 
METHODS 
Could the choice of a National Insurance Plan as the study population have influenced the generalizability 
of the findings ? 
The Authors should cite some literature supporting the idea that a measure of cost is an acceptable 
surrogate measure of disease severity. 
------------------------------------------------------------------------------- 
Discretionary Revisions (which the author can choose to ignore) 
Speaking of causality, the Authors may wish to discuss the limitations of observational studies in detecting 
cause-effect relationships. 
 Accept after minor essential revisions What next?: 
 An article of importance in its field Level of interest: 
 Acceptable Quality of written English: 
 No Statistical review: 
Please review this paper.
user
Reviewer's report 
 Migraine, Fibromyalgia, and Depression Among People With IBS: A Prevalence Study Title: 
 1  17 June 2006 Version: Date: 
 Giorgio Bedogni Reviewer: 
Reviewer's report: 
General 
As a statistical referee, I was asked to answer the question whether the prevalence odds ratio (POR) is an 
effect measure appropriate for the study of Cole and colleagues. 
I did not read the reviews made by the other 2 referees but I suppose that this request was made because 
POR has been criticized in recent years (mainly) on the basis that that when a disease is common, POR may differ from the prevalence rate (PR). 
However, the fact that POR and PR may differ does not tell us which measure is more appropriate to use. 
This will depend from the study context. 
In prevalence case-control studies, such as that of Cole and colleagues, POR may be considered the 
standard effect measure. 
Thus, I believe that the choice of POR as effect measure for this study is appropriate. 
------------------------------------------------------------------------------- 
Major Compulsory Revisions (that the author must respond to before a decision on publication can be reached) 
None 
------------------------------------------------------------------------------- 
Minor Essential Revisions (such as missing labels on figures, or the wrong use of a term, which the author 
can be trusted to correct) 
IN MANY PLACES 
â€œAn higher prevalence / odds ofâ € is better than â €œan increase in the prevalence / odds ofâ €. 
ABSTRACT 
â€œnon-asthmaâ € is â €œnon-IBSâ € 
BACKGROUND 
â€œRome II criteriaâ €, not â €œRome criteriaâ €. 
METHODS 
Could the choice of a National Insurance Plan as the study population have influenced the generalizability 
of the findings ? 
The Authors should cite some literature supporting the idea that a measure of cost is an acceptable 
surrogate measure of disease severity. 
------------------------------------------------------------------------------- 
Discretionary Revisions (which the author can choose to ignore) 
Speaking of causality, the Authors may wish to discuss the limitations of observational studies in detecting 
cause-effect relationships. 
 Accept after minor essential revisions What next?: 
 An article of importance in its field Level of interest: 
 Acceptable Quality of written English: 
 No Statistical review: 
assistant