Review for 10.1186/1471-230X-8-52 (2008)

Reviewer's report
Title:Predictors Of Gastrointestinal Lesions On Endoscopy In Iron Deficiency
Anemia Without Gastrointestinal Symptoms
Version: 1Date:23 January 2008
Reviewer: Alistair W Stewart
Reviewer's report:
Major Compulsory Revisions
1. I would like to see some changes to the structure of the analyses in this paper.
The multivariate logistic regression analyses reported includes variables that
have been shown to be significant by the univariate analyses. (This is not
completely accurate as whether the patients were NSAID users is not included in
the model presented in Table 4.) It is stated elsewhere that gender and ferritin
have been shown to be related to bleeding related endoscopic lesions. Although
these two variables are not shown as statistically significant in Table 3, it is
thought that they are associated with the outcome and so should be included in
the model.
My suggestion is to model, using logistic regression as has been done, the
variables that are reported in the introduction plus any further variables of
interest. These might be the ones shown as significant in the univariate analyses.
I would also suggest that all these variables be presented (rather than footnoting
the non significant ones) in Table 4 so the reader can judge their relative
importance. Therefore, I would suggest that Table 4 reports odds ratios for
gender, ferritin, haemoglobin and NSAIDS as well as the values for the variables
already reported.
The same modelling process should also be used for the predictors for the
causes of iron deficiency.
2. The authors are very careless with their use of decimal places and this needs
to be rectified. A non exhaustive list of examples is:
Table 1 The standard deviation for age should have 1 dp, as should haemoglobin
and the TIBC should have none.
In tables 3 and 5 the presentation of the mean age and standard deviation have
a great variety of decimal point combinations â## this needs fixing.
In tables 4 & 6 the dpâ##s need fixing too.
3. The tables 3 & 5 say that the mean and standard deviation will be presented
as mean (SD) but it is presented as plus/minus. Consistency is needed. I strongly
recommend that the means (SD) format is used as the plus/minus format
indicates some sort of operation can be done, which is meaningless. I know the
plus/minus format is commonly used but it shouldnâ##t be. The number and
percentages should be described too â## for example â##Age >55yrs N (%)â##
should be used as the row description.
4. In table 3 the %â##s associated with the older age are wrong (swapped
column).
In table 5 the %â##s of Hx of weight loss are wrong.
Minor Essential Revisions
5. It is an odds ratio not an odd ratio that comes from the logistic regression.
6. It would be much more informative to the reader if the selection of patients was
described as all eligible patients admitted to Aga Khan University Hospital during
the period from May 2006 to August 2007. Obscuring this behind the words
â##Non-probability purposive sampling techniqueâ## is not helpful.
Discretionary Revisions
7. Tables 3 and 5 both present the results of t-tests. The modelling of this data
does not follow the appropriate order. The outcomes in this study are bleeding
related endoscopic lesions and iron deficiency but they are being used as the
classification variables in the t-tests. Each of these comparisons should be
reversed, that is, use a logistic regression where the outcomes are these binary
variables and the explanatory variables are those used in the t-tests (age, Hb,
MCV, Serum iron, TIBC, transferring saturation and ferritin). In practice, the
resulting p-values are likely to be very similar. It is best for the reader to have the
means given for the two groups (as is already done). I would like to see the
authors make this change in analysis but leave the means. Given that very little
difference will be seen, I am not insisting they do so.
What next?: Unable to decide on acceptance or rejection until the authors have
responded to the major compulsory revisions
Level of interest: An article of importance in its field
Quality of written English: Acceptable
Statistical review: Yes, and I have assessed the statistics in my report.
Declaration of competing interests:
'I declare that I have no competing interests'