Reviewer's report
Title:Predictors Of Gastrointestinal Lesions On Endoscopy In Iron Deficiency
Anemia Without Gastrointestinal Symptoms
Version: 2Date:24 April 2008
Reviewer: Giorgio Bedogni
Reviewer's report:
MINOR REVISIONS
1. If the Authors wish that their model be used to predict the risk of bleeding
lesions, they should give also the regression coefficients (betas) and their
standard errors. The ORs are e^betas but for doing the prediction one needs the
betas. Because the Authors choose to give the ROC curves, they should also
give the betas of the underlying multivariable model.
2. It is important that the Authors write that their model must be cross-validated in
external samples before it can be employed by others.
3. As I suggested before, it is important that the Authors comment on the fact that
the 95%CI of some predictors are wide. For instance, at multivariable analysis, a
FOB+ has a lower 95%CI risk of bleeding lesions equal to 3.9 which is clinically
relevant independently from the fact that the 95% limits are wide (up to 67.3).
The same does not apply to MCV, whose 95%CI range from 1.2 to nearly 10
times more.
4. The Authors have re-performed multivariable logistic regression analysis
adding clinically meaningful predictors (i.e. those already known from the
literature) to their list of predictors identified at univariable analysis.
This is clearly better than the previous analysis based only on univariable
significance but there is the clear disadvantage of no internal cross-validation of
the prediction model, something that the bootstrap would have afforded easily.
5. The Authors write that they used the t-test and the Fisher's exact test for
univariable analysis. However, the give univariable OR in the tables so I suppose
that the p-value in these tables are not that coming from the t-test or the Fisher's
exact test (although they are likely to be similar).
Level of interest: An article whose findings are important to those with closely
related research interests
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'
Reviewer's report
Title:Predictors Of Gastrointestinal Lesions On Endoscopy In Iron Deficiency
Anemia Without Gastrointestinal Symptoms
Version: 2Date:24 April 2008
Reviewer: Giorgio Bedogni
Reviewer's report:
MINOR REVISIONS
1. If the Authors wish that their model be used to predict the risk of bleeding
lesions, they should give also the regression coefficients (betas) and their
standard errors. The ORs are e^betas but for doing the prediction one needs the
betas. Because the Authors choose to give the ROC curves, they should also
give the betas of the underlying multivariable model.
2. It is important that the Authors write that their model must be cross-validated in
external samples before it can be employed by others.
3. As I suggested before, it is important that the Authors comment on the fact that
the 95%CI of some predictors are wide. For instance, at multivariable analysis, a
FOB+ has a lower 95%CI risk of bleeding lesions equal to 3.9 which is clinically
relevant independently from the fact that the 95% limits are wide (up to 67.3).
The same does not apply to MCV, whose 95%CI range from 1.2 to nearly 10
times more.
4. The Authors have re-performed multivariable logistic regression analysis
adding clinically meaningful predictors (i.e. those already known from the
literature) to their list of predictors identified at univariable analysis.
This is clearly better than the previous analysis based only on univariable
significance but there is the clear disadvantage of no internal cross-validation of
the prediction model, something that the bootstrap would have afforded easily.
5. The Authors write that they used the t-test and the Fisher's exact test for
univariable analysis. However, the give univariable OR in the tables so I suppose
that the p-value in these tables are not that coming from the t-test or the Fisher's
exact test (although they are likely to be similar).
Level of interest: An article whose findings are important to those with closely
related research interests
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'
Please review this paper.
user
Reviewer's report
Title:Predictors Of Gastrointestinal Lesions On Endoscopy In Iron Deficiency
Anemia Without Gastrointestinal Symptoms
Version: 2Date:24 April 2008
Reviewer: Giorgio Bedogni
Reviewer's report:
MINOR REVISIONS
1. If the Authors wish that their model be used to predict the risk of bleeding
lesions, they should give also the regression coefficients (betas) and their
standard errors. The ORs are e^betas but for doing the prediction one needs the
betas. Because the Authors choose to give the ROC curves, they should also
give the betas of the underlying multivariable model.
2. It is important that the Authors write that their model must be cross-validated in
external samples before it can be employed by others.
3. As I suggested before, it is important that the Authors comment on the fact that
the 95%CI of some predictors are wide. For instance, at multivariable analysis, a
FOB+ has a lower 95%CI risk of bleeding lesions equal to 3.9 which is clinically
relevant independently from the fact that the 95% limits are wide (up to 67.3).
The same does not apply to MCV, whose 95%CI range from 1.2 to nearly 10
times more.
4. The Authors have re-performed multivariable logistic regression analysis
adding clinically meaningful predictors (i.e. those already known from the
literature) to their list of predictors identified at univariable analysis.
This is clearly better than the previous analysis based only on univariable
significance but there is the clear disadvantage of no internal cross-validation of
the prediction model, something that the bootstrap would have afforded easily.
5. The Authors write that they used the t-test and the Fisher's exact test for
univariable analysis. However, the give univariable OR in the tables so I suppose
that the p-value in these tables are not that coming from the t-test or the Fisher's
exact test (although they are likely to be similar).
Level of interest: An article whose findings are important to those with closely
related research interests
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'
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