Review for 10.1186/1471-230X-11-101 (2011)

Reviewer's report
Title:Determinants of Polyp Size in Patients Undergoing Screening Colonoscopy
Version: 1Date:29 July 2011
Reviewer: Michael Hoffmeister
Reviewer's report:
Thank you very much for this very well written and interesting manuscript on the
clinically relevant topic of determinants of polyp size. There are only few points
that I would like address:
(1) Please be more specific when referring to colorectal cancer, because
sometimes it is not clear whether colon or colon+rectum (or colorectal) is meant
(e.g. Introduction, line 1, Tables).
(2) Introduction, page 4, para 2, line 5: This sounds a bit exaggerated ("reducing
the burden of colorectal cancer") regarding the potential the knowledge of polyp
size determining factors has.
Methods, page 6, para 2,
(3) line 3: is it any family history of colon (or colorectal) cancer, or is it first-degree
family history of CRC? This makes a difference with to CRC risk, and may be
worth discussing in comparison to previous studies on family history and polyp
size if dissimilar definitions were used.
(4) line 5: "this variable" I imagine there can be more than one variable among
the histologic results. Please be more specific (adenomas, hyperplastic polyps?).
It should also be stated in the Methods section why no differentiation was done
between adenomas and hyperplastic polyps, as risks differ quite a lot. Did
previous studies differentiate between size of HPP or adenomas? If yes, a
discussion on potentially different associations would improve the interpretation
of results.
Discussion, page 11, para 3:
(5) Please be more specific when referring to missing underlying pathologic
diagnosis. I think a manuscript on polyp size should include the mention of HPPs,
adenomas, advanced adenomas and cancer, which are all polyps.
"we have no information..." followed by "Restricting the data set to those patients
with a confirmed pathologic diagnosis" is confusing (is pathologic information
available or not?).
(6) An fine description is included that the addition of lifestyle factors and may be
genetic fatcors is required to obtain fully adjusted results. This should also be
mentioned briefly in the limitations section.
Discussion, page 12, para 1:
(7) The potential of bias by not adjusting for previous colonoscopies needs to be
addressed in detail, as this can be a strong cause of bias in your study. I think
this discussion cannot be restricted to age only. You may not have found a
higher risk for larger polyps among those with a family history because these
people may have undergone colonscopy more often. Also, black people are less
likely to have had a colonscopy than white people in the US, which may explain
the larger polyps in black people. People visiting academic sites for colonoscopy
may be more health conscious and thus undergo screening more often than
people visiting community sites.
(8) Finally, please discuss whether adding information from patients with
negative colonoscopies as an addtional comparison group would have been
helpful for the interpretation of results.
Level of interest: An article of outstanding merit and interest in its field
Quality of written English: Acceptable
Statistical review: No, the manuscript does not need to be seen by a
statistician.
Declaration of competing interests:
I declare that I have no competing interests.