Review for 10.1186/s12876-017-0722-6 (2017)

Reviewer ’s report  
 
Title:  Colonoscopy overuse in colorectal cancer screening and associated factors in Argentina: A 
retrospective cohort study.  
 
Version: 0 Date: 14 Jun 2017 
 
Reviewer:  Massimo  Vicentini  
 
Reviewer’s report:  
 
Dear Author,  
 
The topic is really interesting. Colonoscopy is a high -sprea d diagnostic -therapeutic technology, 
but at high risk of inadequacy. The wide range of availability, versatility and defensive medicine 
increases the prescriptive inappropriateness of colonoscopy, with increased waiting lists and 
costs. Consequently, the l iterature reaffirms the need to monitor and reaffirm the 
appropriateness.  
 
The title is clear and self -explanatory, it clearly explains what you are talking about and the type 
of study conducted.  
 
 
Abstract:  
 
Background and objectives: Ok and the goal of the s tudy is clear  
 
Methods: there is an error at the end of paragraph "in a cohort". I would better explain the 
construction criteria of the cohort. Were all subjects> 50 years old who have been admitted from 
1 January to 31 December 2005? Explain the outcome a nd what was measured  
 
 
Results and conclusion: ok  
 
Main text:  
 
Background: I would advise you to better explain which guidelines are taken as a reference 
(USPTF?) The various existing guidelines on colorectal cancer screening recommend very 
different things a t different ages. For example, in Europe it is recommended immunochemical 
occult blood test screening every 2 years in subjects aged 50 -69 years. The USPSTF 
recommends that screening for colorectal cancer start at age 50 years and continue until age 75 
years. For adults aged 76 to 85 years, the decision to screen should be individualized, taking into 
account the patient's overall health and prior screening history.  
 
Aim: What do you mean by complete colonoscopy? How is defined?  Also in the method section 
but it is not described  
Methods:  
 
Study population: Why did not the authors introduce an upper age limit? We are talking about 
screening, so I would use the same range of age guidelines ... eg 50 -75 years.  
 
The elderly have a different cancer incidence, mortal ity and different screening complication 
than the younger ones. Since it is an article about the appropriateness of colonoscopy, probably 
colonoscopy in over 75 subjects are inappropriate.  
 
Furthermore in table 1 there is only IQR median age, but not a desc riptive analysis by age 
groups. A minimum and maximum range is not indicated.  
 
 I would suggest to put an upper limit to 75 years and to add a descriptive analysis by age (only 
the number of subject by age classes).  
 
Discussion: page11, line 30 -48: The sentence on overall mortality is very strong. The assessment 
on the mortality of population screening programs is difficult because it is necessary to identify 
the various factors that may affect the local mortality tren d. Mortality for all causes has also 
declined sharply in the last 20 years, and it is not possible to separate all the factors involved.  
 
Studies on sigmoidoscopy show no statistically significant reductions in mortality, but data 
suggests that there may st ill be an effect. In addition, studies with the guaiac test are too old to be 
taken as a reference, as the immunochemical test is much more sensitive. The lower sensitivity 
of Guaiac may be the reason why no incidence reduction in FOBT trials was observed,  whereas 
now, some observational studies from screening programs using immunochemical have found an 
impact on incidence and incidence -based mortality. It was observed a marked difference between 
incidence based mortality reduction observed in the screening  target age and modest non -
significant reduction in the older ages outside of the screening target.  (Giorgi Rossi P., et al 
2015).  
 
I agree with the authors on the appropriateness of using colonoscopy, but I would not be so 
drastic in asserting that screen ing has no effect on overall mortality.  
 
An effect on specific cause mortality is widely demonstrated, as well as on incidence -based 
overall mortality.  
 
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.  
 
Yes 
 
Are the conclusions drawn adequately supported by the data shown?  
If not, please explain in your comments to the authors.  
 
Yes 
 
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 am able to assess the statistics  
 
Quality of written English  
Please indicate the quality of language in the manuscript:  
 
Acceptable  
 
Declaration of competing interests  
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