Review for 10.1186/1471-230X-11-121 (2011)

Reviewer's report
Title:The impact of laxative use upon symptoms in patients with proven slow
transit constipation: Are infrequent hard stools a reality?
Version: 1Date:29 July 2011
Reviewer: Dominique Dubois
Reviewer's report:
The research presented brings a useful set of diary data on patient self-reported
symptoms. However, the research question posed by the authors is not clearly
defined: The title indicates that the aim was to determine the impact of laxative
use upon symptoms in patients with proven slow transit, and whether infrequent
hard stools are a reality in these patients.
These are in fact two different questions: impact of laxatives on a number of
constipation symptoms versus persistence of typical constipation descriptors
(stool frequency and consistency) during laxative use.
The potential clinical relevance of the second question in particular is debatable.
The real issue of interest is, as suggested by the same authors in their recent
paper (World J Gastroenterol 2011 March 21; 17(11): 1468-1474), “Laxative use
in severely constipated patients may influence the reported symptoms and this
potential confounder needs to be taken into consideration.”
This is an important issue because it is indeed unknown to what extent
laxative-related perturbation of symptoms may contribute to the lack of diagnostic
value of stool frequency and consistency alone, or to the predictive value of
these symptoms for hypothesized underlying mechanisms of dysfunction.
My concern is that the measurement tool used (daily diary) and the study design
are not able to adequately address these questions.
On the other hand, the paper contains quite interesting data on the spectrum of
constipation related symptoms beyond infrequent hard stools: Despite increasing
the stool frequency laxatives had little effect on a patients ability to feel as though
they had completely evacuated. Abdominal pain and bloating were also very
commonly reported and our data suggest these symptoms were intrinsic to the
constipation and not primarily a side-effect of laxatives.
Major Compulsory Revisions
1. Reformulate aim of the paper to include constipation related symptoms beyond
infrequent hard stools in (chronic) laxative users.
2. Expand description of the diary in terms of how developed (where the
symptoms selected on the basis of patient interviews?), reliability, validity and
responsiveness.
3. What was the responder rate? How many (Ad random or not ad random)
missing data? What was time relationship between colonic transit study and
completion of the diaries? What was the variation of each symptom severity over
time? Etc.
4. Delete the COLONIC TRANSIT STUDIES section. It is sufficient to refer to
World J Gastroenterol 2011 March 21; 17(11): 1468-1474).
5. Parts of the discussion or well written and may serve as a basis for the revised
focus on the value of a diary measurement tool. Elaborate on advantages as well
as disadvantages of one-day recall period (diary), versus longer recall periods.
6. Expand the discussion on all symptom findings.
7. State relevant limitations of the study.
8. Consider revising the conclusion to better reflect the most relevant findings of
interest e.g. effect of laxatives upon straining, pain or bloating.
- Minor Essential Revisions
ABSTRACT:
1. Plse check grammar and typo’s:
• Methods: …to the effects on laxatives on constipation symptoms
• Laxatives remain(s) a primary treatment…
• 1 = Present but tolerable (no capital letter needed)
COLONIC TRANSIT STUDIES:
2. All laxative medications were stopped three days before and during the scan:
This does not need mentioned twice in the same paragraph.
DATA ANALYSIS & STATISTICS
3. A day on which laxatives were in effect or not: Plse use either “affect” or
“effect” consistently throughout the text.
RESULTS
4. Plse check grammar: Indeed a regular feeling of feeling of complete
evacuation was reported in just 7 (8%) patients.
DISCUSSION
5. Typo: ... data obtained provided in a stool diaries [9,13].
6. Typo: We feel that based upon these data detailed stool dairies, including
laxative use, must be considered when trying to define a realistic evaluation of
constipation symptoms.
7. Plse check grammar: …many patients ask if they should complete
questionnaire based on what they are like on or off laxatives.
8. Consider rewording: Therefore within any population of constipated patients
questionnaires may be assessing a patient’s estimate of what they believe they
would be like without treatment or what they are actually like on treatment, or
even a combination of both.
9. Typo: To manoeuvrer around the potential impact of laxatives many currently
studies …
10. Typo: …a board cross section. (broad?)
11. Typo: We also did not measure of the size or weight of stool passed …
12. There are potential problems associated with these studies: Plse specify
which studies you refer to.
Discretionary Revisions – Recommendations for improvement
1. Consider clarification of following discussion sections:
• While diaries are more likely to provide a realistic assessment of stool
frequency and form, if they are kept while a patient is off laxatives then they are
also unlikely to reflect the normal day-to-day symptomatology.
• In our own recent study, 4 subtypes were identified, however there was
significant overlap amongst these subtypes [17]. Given that the approach to
constipation subtyping relies entirely on answers provided in a questionnaire, it is
of importance that patients understand how they are supposed to answer the
questionnaire.
• Therefore within any population of constipated patients questionnaires may be
assessing a patient’s estimate of what they believe they would be like without
treatment or what they are actually like on treatment, or even a combination of
both.
2. Did your study offer new insights on the correlation between delayed transit
and constipation symptoms? Could be of interest to discuss in more detail the
straining and sense of incomplete evacuation symptoms. See recent paper by M.
Camilleri (Ther Adv Gastroenterol (2011) 4(3) 159_163) proposing absence of
severe straining severity and manual maneuvers to facilitate defecations (e.g.
digital evacuation, support of the pelvic floor) as excluding criteria for defecatory
disorders.
This proposal was made in the context of a perceived need to revise the
inclusion criteria for patients participating in pharmacodynamic and clinical trials
examining medications intended to treat patients with chronic idiopathic
constipation in the absence of evacuation of defecatory disorders.
In the same journal, W. Whitehead and G. Chiarioni (Ther Adv Gastroenterol
(2011) 4(3) 165_168) commented: “However, we recommend that new symptom
criteria such as those proposed by Dr Camilleri be tested for sensitivity and
specificity to make sure they are able to improve on existing criteria before they
are adopted.”
3. Study population: Would be of interest to comment on the generalizability of
the findings from referrals to tertiary center, candidate for sacral nerve
stimulation.
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.