Reviewer's report
Title:Smoking- and alcohol habits in relation to the clinical picture of women with
microscopic colitis compared to controls
Version:3Date:21 October 2013
Reviewer: Lars Munck
Reviewer's report:
The paper has improved. None the less, and despite the interesting focus I
remain concerned about the validity of the results. The association between MC
and life stile factors including alcohol remains speculative. Information on
medications are not presented. The present finding of different associations of
MC with and without relapse (MC1 and MC2) and smoking study represents an
interesting elaboration of an already presented hypothesis. There are major
problems associated with the method and analysis, and these could be
highlighted more clearly. The first problem is that you have extracted a subgroup
of women with a disease (MC) that matches your large control group, while the
other way around would be more acceptable. The arguments for eliminating
elderly patients do not appear reasonable, and the selection hampers the extend
to which the results can be generalised. Furthermore, the data are collected
years after the diagnosis leaving room for recall bias. Therefore, it is not to know
whether the results are true or merely a result “designed” by the method.
Specific comments
Abstract
Intro, line 1: Symptoms associated with MC and IBS are partly overlapping, not
often.
Aim: “to examine whether the increased risk for MC by smokers is a true
association, or rather the result of confounding factors” would make the case
more clear.
Method: it should be stated that info was obtained retrospectively and the MC
group included was “targeted” and thus selected.
Please state the median age (56) of the control women.
Results last line: “Alcohol drinking had no effect on MC or IBS” effect should be
changed to “no association”.
Introduction
Page 3, 2. para, line 3: the gastrointestinal symptoms are not impaired, I guess
rather gastrointestinal wellbeing?
Page 3, 3 last line: please leave out “north-south gradient”.
Methods
It is maintained that the posthoc exclusion of part of the MC group is problematic
and if maintained is yet another probable bias.
Statistical analysis: ref 22 is a systematic review.
Results
Duration of disease at diagnosis or at follow-up? It should be stated much more
clearly throughout the paper when data refer to the time of diagnosis or to the
recent follow-up. Eg. it is stated in the legend to Tables 1 & 4 that “The values in
smoking- and alcohol habits are based on the last month prior to completion of
study questionnaires”. This information should be provided in the method section.
Discussion
A lengthy discussion of the effect of alcohol on the gut mucosa remains despite
the lack of association, why? Could it be shortened?
On page 14 is the sentence: “However, when elder women search for the same
symptoms, a colonoscopy is requested not to overlook malignancy”. I guess you
mean call on their doctor or something like that. This and other language issues
should be corrected.
The possible bias and confounders should be discussed more thoroughly,
including the selection of a subgroup of patients with MC, in particular exclusion
of the elderly.
Level of interest: An article whose findings are important to those with closely
related research interests
Quality of written English: Needs some language corrections before being
published
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