Review for 10.1186/s12876-015-0395-y (2015)

Reviewer ’s report  
 
Title:  Evaluation of a clinical risk index for advanced colorectal neoplasia among a North 
American population of screening age  
 
Version: 0 Date: 25 Sep 2015  
 
Reviewer: Evelien  Dekker  
 
Reviewer’s report:  
 
In this study the authors evaluated the external validity of a clinical risk index to select persons 
from an average risk population with an increased risk for having advanced ne oplasia based on 
clinical risk factors. This risk score was developed in a European caucasian (Polish) population. 
It appears that the risk score has limited external validity in this Canadian population undergoing 
colonoscopy.  
 
This is a nice example of a risk model that is developed within one population but appears not as 
useful in another setting. However, there are also (potential) defferences between the study -
settings and populations that should be discussed. Please find below my comments.  
 
 
Introductio n: 
 
* In the introduction the authors state that risk factors can either be used with or without flexible 
sigmoidoscopy ("Risk indices for CRC are of two types: .."). I do not see why this statement is 
made. Any test other than colonoscopy can be used in c ombination with risk factors to risk -
stratify for advanced neoplasia, e.g. also FIT (as discussed at the end of the manuscript). Please 
rephrase this paragraph.  
 
 
Methods:  
 
* In the methods section t does not become clear how participants for this study were  selected. 
Was this part of an average -risk screening program? Were individuals invited or did they seek 
medical care at their own initiative? What was the participation -rate to colonoscopy -screening? 
Might this have caused a bias in the population and wha t were potential differences with the 
population in the Polish study?  
 
* The questionnaire was completed by a subgroup of persons that participated in this study. 
Again, I miss participation -rates and discussion of potential bias.  
 
* The questionnaire was de signed for the Canadian population and retrospectively the answers to 
the items that were present in the Polish risk index were used. I can imagine the questions will 
not have been exactly identical (apart form the language). The (potential) differences sh ould be 
discussed.  
Results:  
 
* No remarks  
 
 
Discussion:  
 
* See methods -section: the limitations should be discussed.  
 
Are the methods appropriate and well desc ribed?  
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.  
 
Unable to assess  
 
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 rec ommended, 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, e ither 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 relatin g 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 int erests' 
below. If your reply is yes to any, please give details below.  
 
No financial interest, but I do research in risk -profiling for CRC as well.  
 
I agree to the open peer review policy of the journal. I understand that my name will be included 
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to the editors, which will not be published.  
 
I agree to the open peer review policy of the journal