Review for 10.1186/1471-230X-13-28 (2013)

Reviewer's report
Title:Chronic Fatigue Syndrome 5 years after giardiasis: differential diagnoses,
characteristics and natural course
Version: 2Date:20 September 2012
Reviewer: Daniel Neu
Reviewer's report:
The authors report clinical findings and natural course of CFS and idiopathic
chronic fatigue conditions 5 years after Giardiasis in a limited follow-up sample
out of a larger laboratory confirmed population sample with Giardiasis.
The article is overall well crafted and has its merit. Longitudinal studies of CFS
are certainly of interest within the field of CFS research. There are some syntax
suggestions, remarks on typos and other comments that I broke out in detail
below.
I therefore mainly have suggestions for Minor Essential Revisions and
discretionary comments
General comment:
Several reports over this sample or sub-samples have previously been described
and published by authors or co-authors which are also in part co-authoring the
present ms. Differences rely mainly in assessment instruments and time scales
of cross-sectional, retrospective and longitudinal follow-up designs.
There is certainly interest within the field for theses longitudinal studies, which
describe the natural time course of CFS conditions with potential etiological
definitions. However it should remain the editorial office’s decision whether these
rather epidemiological and partially repeated considerations, as in the present
ms, are of sufficient relevance and crucial interest to a clinical journal in
gastroenterology that already very recently published data from members of the
same group, which used subjects from the same ‘baseline’ sample (although with
different and less precise measurements and with a different study design etc, as
quotedand explained by the authors in the introduction).
At last I would have liked at least some more (even if speculative)
physiopathological or etiopathogenic considerations which could relate, in the
authors’ opinions with respect to the available literature, Giardia duodenalis and
CFS.
Specific comments:
Abstract: ok
Introduction:
p3, paragr1, line2: cancer or other or undefined …chose “other” or “undefinded”
p3, paragr4, last lines: specify that this is not the prevalence of CFS in Norway (!)
..suggestion: Unspecified chronic fatigue has previously..
Methods:
Patients were included among patients… : change sentence .. subjects were
included among patients or patients..among the sample that fulfilled..
p4, last lines 1st paragr: 88 were excluded : could the authors comment on this ?
p4, 3rd paragr, the Mini was used ..and the MADRS was used or the MINI and
the MADRS were used..please correct
p5, last sentence 1st paragr: two different teams of psychiatrists …please
comment : why ? are both “teams” among the authors ? who are they ?
Results:
p5, last paragr: 79.1% of the contacted patients/subjects refused to participate in
the study …could the authors comment on the main reasons?
p6, 3rd paragraph, 1st line: had a mean BMI ..compared to a mean of ..among..
Discussion:
(global and specific comments)
Overall, we found that the discussion is somewhat a little bit poor. The authors
come across the main findings of the questionnaires, interviews and para-clinical
findings from their sample. As previously mentioned, a more integrative view on a
complex multifactorial condition as CFS, even if etiological triggers are identified
(i.e. Giardia..) could be provided here.
Clinical and research-related confusions about fatigue and sleepiness are
unfortunately still frequent.
Sleepiness, directly linked to sleep, improves if excessively present and related
to a primary sleep disorder, whereas fatigue (complex, multifactorial and
indirectly related to sleep) often or mostly does not if chronic at treatment
onset…Although different concepts, chronic daytime fatigue and excessive
daytime sleepiness may though also overlap in severe conditions….the authors
may acknowledge these differences/considerations during their discussion about
OSAS (SAHS) and CFS/fatigue…
5 patients had SAHS..and the authors consider the latter as an important
differential diagnosis..? What were their individual AHI? Could the authors please
comment on this.
The paper slightly misses to strike out what a reader should really learn from this
study and why it is important to continue conducting similar studies. The
conclusion could therefore be slightly more explicit.
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:
No to all of the above