Review for 10.1186/s12876-014-0217-7 (2014)

Reviewer's report
Title:Prospective cross-sectional study on faecal immunochemical tests: sex
specific cut-off values to obtain equal sensitivity for colorectal cancer?
Version:5Date:5 August 2014
Reviewer: Preet Paul Singh
Reviewer's report:
Reviewer's report:
Turenhout and colleagues have tried to answer an interesting question, that of
varying sensitivity of fecal immunochemical tests (FIT) in men and women. They
also aim to find plausible reasons that may explain this difference via a
cross-sectional study of nearly 3000 individuals that underwent FIT before
colonoscopy. The major finding was that FIT was found to be more sensitive and
less specific for CRC in men than in women. No difference for advanced
adenomas.
Major Points
1. Methods - exclusion criteria - Please define “clinical suspicion of CRC”. It
appears from table 1, lot of patients had weight loss and change in bowel habits
that can raise suspicion of CRC.
2. The endoscopists were blinded to the FIT result which appears to reduce bias;
but it should be considered that in many real life situations, colonoscopy follows a
known positive FIT result. Therefore, one wonders whether sensitivity/specificity
in this study are truly generalizable to real-life practice?
3. Page 7, Line 158 “Subjects with CRC or advanced adenomas on both sides of
the colon were excluded from these analyses.” I am unsure if this is appropriate,
especially with one of the variables being 1 or >1 advanced adenomas. Authors
can consider classifying these patients into left or right colon based on this “In
case of multiple neoplasia detected on colonoscopy, patients were classified
based on the most advanced lesion found.”
4. Positivity rates (Line 192) – please also report data for >75 as that is the
recommended cut-off based off of the test kit manufacturer. Also see #7.
5. Page 13, Line 274 - Another reason for sex differences in sensitivity and
specificity might be the sex difference in colonic transit time: among women,
colonic transit has been found to be slower than among men – ref Rao et al,
CGH 2009 (http://www.ncbi.nlm.nih.gov/pubmed/19418602)
6. Page 15, Line 301 – Please consider discussing/including this reference here
(Denters et al, Gastroenterology 2012
http://www.ncbi.nlm.nih.gov/pubmed/22108194) which shows that positive
predictive value of FIT for advanced neoplasia and for CRC are significantly
lower among subsequent FIT participants who tested negative the first time
around.
7. Table 2 – As a cut-off of #75 ng/ml is advised by the manufacturer, I would
suggest that we report “positive” rates based off of that instead of >50 – as the
manufacturer did some standardization and testing before selecting that cut-off.
8. Table 4 – its unclear what the reference category for gender is for the odds
ratio. Please include that in a foot note.
- Minor Essential Revisions
1. Page 5, Line 109 – please state “fecal hemoglobin concentrations of ….”
2. Multiple places in results – please use decimal places instead of commas.
3. The authors use the term ‘sex’ and ‘gender’ interchangeably in the manuscript.
In the context of this study, “sex” may be a more appropriate term as there may
be biological differences between males and females explaining the results
Level of interest: An article of importance in its field
Quality of written English: Acceptable
Statistical review: Yes, and I have assessed the statistics in my report.
Declaration of competing interests:
I declare that I have no competing interests