Review for 10.1186/1471-230X-13-82 (2013)

Reviewer's report
Title:Barrett's esophagus and the risk of obstructive sleep apnea: A case-control
study
Version: 2Date:18 January 2013
Reviewer: Össur Ingi Emilsson
Reviewer's report:
The authors have reacted positively on the former comments on their manuscript.
It is now more coherent, better presented and takes better into account the
limitations of the study. However, there is still a need for improvement, and this
better presentation of the data kindles new questions and thoughts on the study.
Major Compulsory Revisions
1. The primary aim of this study is to determine whether patients with BE are
more likely to be at risk for OSA. That is, this study is searching for a high-risk
group for OSA. It would therefore be appropriate to have the end-point of all
analyses OSA. On page 12, parag. 2, the whole analysis has to be turned around
to fulfill this. For example, instead of „Among all patients who were BQ+ [...], the
rate of nocturnal heartburn was 31%“ it should read „Among all patients who had
nocturnal heartburn [...], the rate of BQ+ was ??“, etc.
2. Similarly, table 4 needs to be reversed (see attached .xls document). In this
new table, it seems clear that the combination of nocturnal gastroesophageal
reflux (nGER) and BE is very predictive of a positive Berlin Questionnaire.
However, this new analysis of the data also shows that nGER in general seems
to be a stronger risk factor than BE status, which is a very interesting finding and
needs to be reflected upon in the article. Around 68% of those with BE and
nGER are BQ+, compared with 35% of those only with BE. One interpretation of
this new data is that BE might be associated with OSA through a higher
incidence of nGER. Therefore, the article needs to be revised in whole with
regard to this. For example, in the conclusions of the abstract, instead of
„Screening for obstructive sleep apnea in Barrett‘s esophagus patients should be
considered...“ it should read „Screening for obstructive sleep apnea in Barrett‘s
esophagus patients with nocturnal GERD symptoms should be considered...“,
etc.
3. To summarize, it now seems that nGER might be the main culprit. This needs
special focus in the article. Is nGER more common in BE than other GER-related
illnesses? As some have speculated, is nGER a sign of a more severe illness?
Minor Essential Revisions
1. It is slightly too bold to say that this study is sufficient to justify OSA screening
in this group. Therefore, in the conclusions of the abstract, instead of „Screening
for [see point 2 in major revisions] should be considered...“ it should read „The
need for OSA screening in [see point 2 in major revisions] should be further
evaluated...“.
2. The authors should explain why subjects with known OSAS were excluded. As
these subjects were mostly in the BE group, this might confound the results
significantly, and should be addressed both in the methods section and the
discussion, and in the limitations part. The authors might even add a few
calculations where these subjects are added as being BQ+.
3. On page 6, parag. 1, the following sentence should be deleted „Control
subjects were recruited at the time of endoscopy or soon thereafter“. The next
sentence says exactly the same, only with more information.
4. On page 8, parag. 1, this single sentence is not clear enough. I guess it should
read: „Nocturnal regurgitation was imputed as absent for 1 COL patient who
reported an awakening by nocturnal regurgitation in the past year, but rated his
usual acid regurgitation symptoms as nonexistent.“
5. On page 10, parag. 1, change „...COL group were less likely to be male and
white“ to „...COL group were more likely to be male and white“.
Discretionary Revisions
1. On page 13, parag. 1, remove space in the end of line 6 before reference 26,
„...in the development of BE;[26]...“
2. In the list of references, page numbers are missing in reference 26 (Greer KB,
Thompson CL et al, Gut, 2011). Also, according to the home page of otolaryngol
head neck surg, reference 34 is from page P227 to P228.
3. In Figure 1 (the BQ with GERD questions), in 1B, questions about heartburn,
second point: Change „Has heartburn had awakened...“ to „Has heartburn
awakened...“.
Level of interest: An article whose findings are important to those with closely
related research interests
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.