Reviewer's report
Title:Predictors Of Gastrointestinal Lesions On Endoscopy In Iron Deficiency
Anemia Without Gastrointestinal Symptoms
Version: 1Date:14 January 2008
Reviewer: Giorgio Bedogni
Reviewer's report:
I reviewed this paper as BMC statistical referee. I was blinded to the reviews
made by the other referees.
Major Compulsory Revisions
1. As study design is concerned (abstract and elsewhere), please write â##This
is a cross-sectional study performed on a convenience sample of consecutive
subjectsâ##.
2. Please explain why you dichotomized continuous predictors at the given
cut-points. Categorization of a continuous variable involves loss of information so
that it is important that you justify the choice of these cut-points.
3. Statistical significance at univariable analysis was the criterion by which
potential predictors were entered into multivariable models. (This is not stated but
can be inferred from the data.) This is a common approach but has *many*
disadvantages, especially when there are many predictors (12) with few positive
outcomes (50 bleeding lesions). A multivariable selection of predictors using
bootstrap would improve substantially your conclusions (Steyerberg, E. W.,
Harrell, F. E., Borsboom, G. J., Eijkemans, M. J., Vergouwe, Y., & Habbema, J.
D. (2001). Internal validation of predictive models: efficiency of some procedures
for logistic regression analysis. J Clin Epidemiol, 54(8), 774-781.)
4. Specify whether age is dichotomized in Tables 4 and 6 as it is in Tables 3 and
5.
5. Please discuss the fact that the 95%CI for some predictors (e.g. iron) are
compatible with modest to very high effects. (That it is, the precision of the
estimate is low).
6. You say that your models may be useful to â##predictâ## bleeding lesions.
However, you do not give data to evaluate their diagnostic accuracy. If the
emphasis is on the prediction of bleeding lesions (and not on the identification of
risk factors), you should report accuracy data. The simplest thing to do is to
report the non-parametric area of a ROC curve.
Minor Essential Revisions
7. Please quote the literature showing that the 3 methods by which you
diagnosed anemia are equivalent for this purpose.
8. Results: lumphoma is lymphoma.
9. Tables 4 and 6: write â##oddsâ## instead of â##ODDâ##.
Discretionary Revisions
10. Since you evaluated both patients with and without GI symptoms, wouldnâ##t
it be interesting to compare predictors in these 2 subgroups ?
What next?: Unable to decide on acceptance or rejection until the authors have
responded to the major compulsory revisions
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
Reviewer's report
Title:Predictors Of Gastrointestinal Lesions On Endoscopy In Iron Deficiency
Anemia Without Gastrointestinal Symptoms
Version: 1Date:14 January 2008
Reviewer: Giorgio Bedogni
Reviewer's report:
I reviewed this paper as BMC statistical referee. I was blinded to the reviews
made by the other referees.
Major Compulsory Revisions
1. As study design is concerned (abstract and elsewhere), please write â##This
is a cross-sectional study performed on a convenience sample of consecutive
subjectsâ##.
2. Please explain why you dichotomized continuous predictors at the given
cut-points. Categorization of a continuous variable involves loss of information so
that it is important that you justify the choice of these cut-points.
3. Statistical significance at univariable analysis was the criterion by which
potential predictors were entered into multivariable models. (This is not stated but
can be inferred from the data.) This is a common approach but has *many*
disadvantages, especially when there are many predictors (12) with few positive
outcomes (50 bleeding lesions). A multivariable selection of predictors using
bootstrap would improve substantially your conclusions (Steyerberg, E. W.,
Harrell, F. E., Borsboom, G. J., Eijkemans, M. J., Vergouwe, Y., & Habbema, J.
D. (2001). Internal validation of predictive models: efficiency of some procedures
for logistic regression analysis. J Clin Epidemiol, 54(8), 774-781.)
4. Specify whether age is dichotomized in Tables 4 and 6 as it is in Tables 3 and
5.
5. Please discuss the fact that the 95%CI for some predictors (e.g. iron) are
compatible with modest to very high effects. (That it is, the precision of the
estimate is low).
6. You say that your models may be useful to â##predictâ## bleeding lesions.
However, you do not give data to evaluate their diagnostic accuracy. If the
emphasis is on the prediction of bleeding lesions (and not on the identification of
risk factors), you should report accuracy data. The simplest thing to do is to
report the non-parametric area of a ROC curve.
Minor Essential Revisions
7. Please quote the literature showing that the 3 methods by which you
diagnosed anemia are equivalent for this purpose.
8. Results: lumphoma is lymphoma.
9. Tables 4 and 6: write â##oddsâ## instead of â##ODDâ##.
Discretionary Revisions
10. Since you evaluated both patients with and without GI symptoms, wouldnâ##t
it be interesting to compare predictors in these 2 subgroups ?
What next?: Unable to decide on acceptance or rejection until the authors have
responded to the major compulsory revisions
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
Please review this paper.
user
Reviewer's report
Title:Predictors Of Gastrointestinal Lesions On Endoscopy In Iron Deficiency
Anemia Without Gastrointestinal Symptoms
Version: 1Date:14 January 2008
Reviewer: Giorgio Bedogni
Reviewer's report:
I reviewed this paper as BMC statistical referee. I was blinded to the reviews
made by the other referees.
Major Compulsory Revisions
1. As study design is concerned (abstract and elsewhere), please write â##This
is a cross-sectional study performed on a convenience sample of consecutive
subjectsâ##.
2. Please explain why you dichotomized continuous predictors at the given
cut-points. Categorization of a continuous variable involves loss of information so
that it is important that you justify the choice of these cut-points.
3. Statistical significance at univariable analysis was the criterion by which
potential predictors were entered into multivariable models. (This is not stated but
can be inferred from the data.) This is a common approach but has *many*
disadvantages, especially when there are many predictors (12) with few positive
outcomes (50 bleeding lesions). A multivariable selection of predictors using
bootstrap would improve substantially your conclusions (Steyerberg, E. W.,
Harrell, F. E., Borsboom, G. J., Eijkemans, M. J., Vergouwe, Y., & Habbema, J.
D. (2001). Internal validation of predictive models: efficiency of some procedures
for logistic regression analysis. J Clin Epidemiol, 54(8), 774-781.)
4. Specify whether age is dichotomized in Tables 4 and 6 as it is in Tables 3 and
5.
5. Please discuss the fact that the 95%CI for some predictors (e.g. iron) are
compatible with modest to very high effects. (That it is, the precision of the
estimate is low).
6. You say that your models may be useful to â##predictâ## bleeding lesions.
However, you do not give data to evaluate their diagnostic accuracy. If the
emphasis is on the prediction of bleeding lesions (and not on the identification of
risk factors), you should report accuracy data. The simplest thing to do is to
report the non-parametric area of a ROC curve.
Minor Essential Revisions
7. Please quote the literature showing that the 3 methods by which you
diagnosed anemia are equivalent for this purpose.
8. Results: lumphoma is lymphoma.
9. Tables 4 and 6: write â##oddsâ## instead of â##ODDâ##.
Discretionary Revisions
10. Since you evaluated both patients with and without GI symptoms, wouldnâ##t
it be interesting to compare predictors in these 2 subgroups ?
What next?: Unable to decide on acceptance or rejection until the authors have
responded to the major compulsory revisions
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
assistant