Review for 10.1186/1471-230X-12-94 (2012)

Reviewer's report
Title:The value of a faecal immunochemical test in colorectal cancer
surveillance: a multi-centre cohort study
Version: 1Date:16 February 2012
Reviewer: Enrique Quintero
Reviewer's report:
The limited resources of endoscopy units are a timely subject and the
investigation of strategies to relief the burden on colonoscopy capacity are
welcome. This paper addresses the provocative hypothesis that colonoscopy
surveillance in high-risk patients for colorectal cancer (CRC) could be modulated
by previous fecal immunochemical testing (FIT). The authors retrospectively
analyzed the accuracy of one or two samples of a sensitive FIT for detecting
advanced colorectal neoplasm in subjects with personal history of
adenomas/CRC or family history of CRC. They concluded that a once-only FIT
strategy is inadequate in detecting advanced neoplasia in either group of
high-risk individuals.
Although the study is well written there are several areas in which greater clarity
is needed (see below).
Major compulsory revisions
1) The aim of the study does not remain clear along the manuscript. As stated in
the abstract, “the aim of this study was to verify whether surveillance of
asymptomatic high-risk individuals can be based on FIT sampling, with
colonoscopy referral only in case of a positive FIT result”. However, in the last
paragraph of the introduction they remark that the study “evaluates the test
characteristics of single and double FIT sampling to detect CRC and/or advanced
adenomas in a colonoscopy-controlled high-risk population”, which is not the
same. I understand that the study design and results are more in accordance
with this later statement than with the aim expressed in the abstract, that should
be modified. To answer the question whether surveillance colonoscopy could be
modified following FIT sampling, patients should follow the recommended
intervals. However, no data is presented regarding this crucial point. To better
clarify this question the authors should provide information regarding whether
these high-risk individuals did undergo colonoscopy at the adequate intervals (as
recommended in practice guidelines) or not, and how many had only one
surveillance round or several rounds. This question is not obvious in the Methods
nor in the Results sections. Greater clarify regarding this point would strengthen
the paper.
2) The authors classified surveillance colonoscopies according if they were
performed within the last 2 years before FIT samplin or not. However, this
interval time is not accepted for surveillance colonoscopy in most high-risk
patients. Please, clarify why you chose this criterion.
3) Colonoscopy quality: diagnostic yield rate require assumptions regarding the
quality of the colonoscopy. Accepted metrics include the adenoma detection rate,
cecal intubation rate, colonoscopy withdrawal time and others. How can we be
sure that colonoscopy quality was ensured? Was it measured?
4) The authors assumed as high-risk individuals for CRC, those with personal
history of CRC/adenoma or with a family history of CRC. Regarding this later
group it is well known that the risk for CRC is related to the index case age and
to the number of first-degree relatives affected. According to these criteria, in the
Methods it is stated that patients were classified as having “significant” (n=259)
or “not significant” (n=104) family history of CRC. Indeed, individuals with a “not
significant” family history should not be considered as high-risk for CRC and
some current guidelines do recommend FOBT starting at 40 years of age,
instead of colonoscopy. This subgroup with “moderate” risk represented 30% of
the first-degree relatives included in this study, a fact that could explain the lower
FIT positivity rate found in the familiar-risk individuals as compared to the other
two high-risk groups. I suggest to remove from the analysis the 104 individuals
with moderate but not high-risk condition.
6) The authors apparently calculated the potential effect of FIT sampling in 5
consecutive rounds. These data are shown in the abstract and a commented at
the discussion, but nothing was mentioned in other sections of the manuscript.
Please, provide detailed information regarding this analysis in the methods and
results.
7) The authors should better discuss the discrepancies regarding their results on
FIT positivity rate and those found by Hazazi et al? It doesn't look just a matter of
a higher percentage of neoplastic lesions as their sensitivity is much lower.
2) Minor compulsory revisions.
1) Please, include the results of the logistic regression analysis (page 13).
2) Please, provide how was collected the participant's family history? Was this
information self-reported?
3) In the Results section it is mentioned that “The date and findings of the last
colonoscopy prior to FIT sampling were known for 872/1041 patients (84%). In
305 patients the previous colonoscopy was within two years of the current
colonoscopy and FIT. A total of 386 patients had a colonoscopy more than two
years prior to their current colonoscopy and FIT.” But 305+386 = 691 ¿when
were performed the remaining 181 colonoscopies?
Level of interest: An article of importance 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 don´t have conflict of interest