Reviewer’s report
Title: 
No association of serum ferritin levels with advanced liver fibrosis in
untreated German patients with autoimmune hepatitis
Version: 
1 
Date: 
19 Aug 2022
Reviewer's report:
The authors incorporated most of the suggested modifications, however there are
still a few issues that need to be corrected.
1) The authors stated in their answer: "According to our biometric counselling,
that we performed during the preparation of the Letter we were instructed that a
validation of results does not implicate to start a new modelling (meaning a new
logistic regression analysis) but rather to apply the cut-off identified in the
training cohort (the Chinese cohort from Chen et al.). Therefore, we applied the
ferritin cut-off of 199 µg/ml and found no significant association of a ferritin
level above 199 µg/l with advanced fibrosis in our German cohort." 
I think there is a misunderstanding here. It is true that when there is a defined
cut-off level, the authors need to validate that cut-off during the validation
process and not define a new one in their cohort. Therefore, the comparison part
of the present study is correctly done. However, in the logistic regression
analysis, Chen et al used ferritin level as a continuous variable (dichotomisation
by the cut-off level of 199 µg/L happened later). If one performs univariate
logistic regression on ferritin levels and include the same factors in the
multivariate analysis that was reported in the original article that is not a new
modelling but the only way to validate the odds ratios reported in the original
study. It does not matter how little is the likelihood of a statistically significant
result it still needs to be shown. (Of note, lack of statistical significance in case
of the univariate analysis is enough to disprove the previous finding and no
further multivariate analysis is needed). However, I agree that it most probably
will not change the conclusion of the paper, since the results of both the ROC
analysis and the comparison by the cut-off level were not statistically significant
in contrast to what Chen et al reported.
2) What did the authors mean by "The odds ratio for advanced fibrosis using
absolute
ferritin levels with a cut-off of 199 
μ
g/l as published by Chen et al. was 1.444
(95% CI 0.571 -
3.653)." Did the authors perform logistic regression using the cut-off value
instead of using ferritin as a continuous variable? Why did they find this more
appropriate? Please be specific when explaining the performed analyses in the
text!
3) The authors misinterpreted the reason for logarithmic transformation.
Logarithmic transformation is not necessary for a simple comparative test, since
methods to compare not normally distributed populations exist (Mann-Whitney)
that the authors also used (table 1). Logarithmic transformation was suggested as
a possible tool to increase the odds ratio of the regression analysis (since it
showed only a marginal effect in the article from Chen at al).
4) I assume, instead of "compensated for by using binary logistic regression and
multivariate regression analysis" (top of page 3), the authors wanted to write
"corrected by including these parameters in the univariate and multivariate
binary logistic regression analyses".
5) There is another confusion around the sentence "Both approaches have their
pros and cons which is why we presented both." 
When I wrote it in my comments, I was referring to the sentence quoted in point
4). I.e.: approach one - including the interfering parameters in the univariate and
multivariate regression analyses; and approach two: correcting for the upper
limit of normal. However, the authors, as it was discussed above, did not present
the results of the univariate and multivariate regression analyses using ferritin as
a continuous variable like Chen et al did.
Considering the immediately preceding sentence the authors probably meant that
they performed comparison between fibrotic and non-fibrotic patients and also
carried out ROC analysis using both absolute and corrected ferritin levels. But
this is also confusing without explaining what the mentioned pros and cons are in
this case. Furthermore, the authors also mentioned the logarithmic
transformation which made it even less clear what they were talking about.
I suggest that the logarithmically transformed ferritin level be omitted from the
comparative analysis, and instead of the quoted sentence, simply state that the
authors believe that the results obtained using ULN-corrected ferritin levels are
more valid than the results obtained using the absolute values, but both is
presented for fair validation.
6) The manuscript contains several grammatical errors. Please perform a
grammar check!
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Please complete a declaration of competing
interests, considering the following questions:
1
. 
Have you in the past five years received reimbursements, fees, funding, or
salary from an organisation that may in any way gain or lose financially
from the publication of this manuscript, either now or in the future?
2
. 
Do you hold any stocks or shares in an organisation that may in any way
gain or lose financially from the publication of this manuscript, either now
or in the future?
3
. 
Do you hold or are you currently applying for any patents relating to the
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Have you received reimbursements, fees, funding, or salary from an
organization that holds or has applied for patents relating to the content of
the manuscript?
5
. 
Do you have any other financial competing interests?
6
. 
Do you have any non-financial competing interests in relation to this
paper?
If you can answer no to all of the above, write 'I declare that I have no competing
interests' below. If your reply is yes to any, please give details below.
I declare that I have no competing interests.
Reviewer Publication Consent.
 I agree for my report to be made available
under an Open Access Creative Commons CC-BY License (
http://creativecommons.org/licenses/by/4.0
) if this manuscript is accepted for
publication. Any comments that I do not wish to be included in the published
report have been included as confidential comments to the editor, which will not
be published.
If you are not happy for us to publish this report, please contact the
editorial office before completing the review.
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name in your published report. Please note you must decide whether to include
your name at the start of the process and confirm this decision whenever
prompted. If you change your decision later, we will not be able to publish your
name.
I agree to the terms of the CC-BY 4.0 license; please 
do not
 publish my name
with my report. (default)
Is the study design appropriate to answer the research question (including the use
of appropriate controls), and are the conclusions supported by the evidence
presented?
Yes
Are the methods sufficiently described to allow the study to be repeated?
Yes
Is the use of statistics and treatment of uncertainties appropriate?
Yes
Is the presentation of the work clear?
No
Are the images in this manuscript (including electrophoretic gels and blots) free
from apparent manipulation?
Yes
Reviewer’s report
Title: 
No association of serum ferritin levels with advanced liver fibrosis in
untreated German patients with autoimmune hepatitis
Version: 
1 
Date: 
19 Aug 2022
Reviewer's report:
The authors incorporated most of the suggested modifications, however there are
still a few issues that need to be corrected.
1) The authors stated in their answer: "According to our biometric counselling,
that we performed during the preparation of the Letter we were instructed that a
validation of results does not implicate to start a new modelling (meaning a new
logistic regression analysis) but rather to apply the cut-off identified in the
training cohort (the Chinese cohort from Chen et al.). Therefore, we applied the
ferritin cut-off of 199 µg/ml and found no significant association of a ferritin
level above 199 µg/l with advanced fibrosis in our German cohort." 
I think there is a misunderstanding here. It is true that when there is a defined
cut-off level, the authors need to validate that cut-off during the validation
process and not define a new one in their cohort. Therefore, the comparison part
of the present study is correctly done. However, in the logistic regression
analysis, Chen et al used ferritin level as a continuous variable (dichotomisation
by the cut-off level of 199 µg/L happened later). If one performs univariate
logistic regression on ferritin levels and include the same factors in the
multivariate analysis that was reported in the original article that is not a new
modelling but the only way to validate the odds ratios reported in the original
study. It does not matter how little is the likelihood of a statistically significant
result it still needs to be shown. (Of note, lack of statistical significance in case
of the univariate analysis is enough to disprove the previous finding and no
further multivariate analysis is needed). However, I agree that it most probably
will not change the conclusion of the paper, since the results of both the ROC
analysis and the comparison by the cut-off level were not statistically significant
in contrast to what Chen et al reported.
2) What did the authors mean by "The odds ratio for advanced fibrosis using
absolute
ferritin levels with a cut-off of 199 
μ
g/l as published by Chen et al. was 1.444
(95% CI 0.571 -
3.653)." Did the authors perform logistic regression using the cut-off value
instead of using ferritin as a continuous variable? Why did they find this more
appropriate? Please be specific when explaining the performed analyses in the
text!
3) The authors misinterpreted the reason for logarithmic transformation.
Logarithmic transformation is not necessary for a simple comparative test, since
methods to compare not normally distributed populations exist (Mann-Whitney)
that the authors also used (table 1). Logarithmic transformation was suggested as
a possible tool to increase the odds ratio of the regression analysis (since it
showed only a marginal effect in the article from Chen at al).
4) I assume, instead of "compensated for by using binary logistic regression and
multivariate regression analysis" (top of page 3), the authors wanted to write
"corrected by including these parameters in the univariate and multivariate
binary logistic regression analyses".
5) There is another confusion around the sentence "Both approaches have their
pros and cons which is why we presented both." 
When I wrote it in my comments, I was referring to the sentence quoted in point
4). I.e.: approach one - including the interfering parameters in the univariate and
multivariate regression analyses; and approach two: correcting for the upper
limit of normal. However, the authors, as it was discussed above, did not present
the results of the univariate and multivariate regression analyses using ferritin as
a continuous variable like Chen et al did.
Considering the immediately preceding sentence the authors probably meant that
they performed comparison between fibrotic and non-fibrotic patients and also
carried out ROC analysis using both absolute and corrected ferritin levels. But
this is also confusing without explaining what the mentioned pros and cons are in
this case. Furthermore, the authors also mentioned the logarithmic
transformation which made it even less clear what they were talking about.
I suggest that the logarithmically transformed ferritin level be omitted from the
comparative analysis, and instead of the quoted sentence, simply state that the
authors believe that the results obtained using ULN-corrected ferritin levels are
more valid than the results obtained using the absolute values, but both is
presented for fair validation.
6) The manuscript contains several grammatical errors. Please perform a
grammar check!
Publons Reviewer Recognition
. Springer Nature can send verification of this
review directly to Publons (a subsidiary of Clarivate Analytics). If you would
like to take advantage of this service, please click on the “Yes” option below.
Your name, email address, title of the reviewed manuscript, name of the journal,
and date of your review submission (the “Review Data”) will then be transmitted
to Publons after the final decision on the manuscript has been made. If you have
already registered at Publons, they will notify you of the receipt of this review
and update your profile 
as per your settings and their policy. If you are not
registered with Publons, you will receive an email from them asking you to
register in order for them to be able to recognize your review on your new
profile page. Publons may use the Review Data to generate derivative metadata
for the benefit of Publons and you as a reviewer, carefully considering the
sensitivity of such information. For example, Publons may verify your record as
a reviewer by updating your profile published on its webservice if you have
registered for such service or help editors to identify candidate reviewers. Please
find the details of processing in Publons’ privacy policy
https://publons.com/about/terms
No
Declaration of competing interests
Please complete a declaration of competing
interests, considering the following questions:
1
. 
Have you in the past five years received reimbursements, fees, funding, or
salary from an organisation that may in any way gain or lose financially
from the publication of this manuscript, either now or in the future?
2
. 
Do you hold any stocks or shares in an organisation that may in any way
gain or lose financially from the publication of this manuscript, either now
or in the future?
3
. 
Do you hold or are you currently applying for any patents relating to the
content of the manuscript?
4
. 
Have you received reimbursements, fees, funding, or salary from an
organization that holds or has applied for patents relating to the content of
the manuscript?
5
. 
Do you have any other financial competing interests?
6
. 
Do you have any non-financial competing interests in relation to this
paper?
If you can answer no to all of the above, write 'I declare that I have no competing
interests' below. If your reply is yes to any, please give details below.
I declare that I have no competing interests.
Reviewer Publication Consent.
 I agree for my report to be made available
under an Open Access Creative Commons CC-BY License (
http://creativecommons.org/licenses/by/4.0
) if this manuscript is accepted for
publication. Any comments that I do not wish to be included in the published
report have been included as confidential comments to the editor, which will not
be published.
If you are not happy for us to publish this report, please contact the
editorial office before completing the review.
If you wish, you can include your
name in your published report. Please note you must decide whether to include
your name at the start of the process and confirm this decision whenever
prompted. If you change your decision later, we will not be able to publish your
name.
I agree to the terms of the CC-BY 4.0 license; please 
do not
 publish my name
with my report. (default)
Is the study design appropriate to answer the research question (including the use
of appropriate controls), and are the conclusions supported by the evidence
presented?
Yes
Are the methods sufficiently described to allow the study to be repeated?
Yes
Is the use of statistics and treatment of uncertainties appropriate?
Yes
Is the presentation of the work clear?
No
Are the images in this manuscript (including electrophoretic gels and blots) free
from apparent manipulation?
Yes
Please review this paper.
user
Reviewer’s report
Title: 
No association of serum ferritin levels with advanced liver fibrosis in
untreated German patients with autoimmune hepatitis
Version: 
1 
Date: 
19 Aug 2022
Reviewer's report:
The authors incorporated most of the suggested modifications, however there are
still a few issues that need to be corrected.
1) The authors stated in their answer: "According to our biometric counselling,
that we performed during the preparation of the Letter we were instructed that a
validation of results does not implicate to start a new modelling (meaning a new
logistic regression analysis) but rather to apply the cut-off identified in the
training cohort (the Chinese cohort from Chen et al.). Therefore, we applied the
ferritin cut-off of 199 µg/ml and found no significant association of a ferritin
level above 199 µg/l with advanced fibrosis in our German cohort." 
I think there is a misunderstanding here. It is true that when there is a defined
cut-off level, the authors need to validate that cut-off during the validation
process and not define a new one in their cohort. Therefore, the comparison part
of the present study is correctly done. However, in the logistic regression
analysis, Chen et al used ferritin level as a continuous variable (dichotomisation
by the cut-off level of 199 µg/L happened later). If one performs univariate
logistic regression on ferritin levels and include the same factors in the
multivariate analysis that was reported in the original article that is not a new
modelling but the only way to validate the odds ratios reported in the original
study. It does not matter how little is the likelihood of a statistically significant
result it still needs to be shown. (Of note, lack of statistical significance in case
of the univariate analysis is enough to disprove the previous finding and no
further multivariate analysis is needed). However, I agree that it most probably
will not change the conclusion of the paper, since the results of both the ROC
analysis and the comparison by the cut-off level were not statistically significant
in contrast to what Chen et al reported.
2) What did the authors mean by "The odds ratio for advanced fibrosis using
absolute
ferritin levels with a cut-off of 199 
μ
g/l as published by Chen et al. was 1.444
(95% CI 0.571 -
3.653)." Did the authors perform logistic regression using the cut-off value
instead of using ferritin as a continuous variable? Why did they find this more
appropriate? Please be specific when explaining the performed analyses in the
text!
3) The authors misinterpreted the reason for logarithmic transformation.
Logarithmic transformation is not necessary for a simple comparative test, since
methods to compare not normally distributed populations exist (Mann-Whitney)
that the authors also used (table 1). Logarithmic transformation was suggested as
a possible tool to increase the odds ratio of the regression analysis (since it
showed only a marginal effect in the article from Chen at al).
4) I assume, instead of "compensated for by using binary logistic regression and
multivariate regression analysis" (top of page 3), the authors wanted to write
"corrected by including these parameters in the univariate and multivariate
binary logistic regression analyses".
5) There is another confusion around the sentence "Both approaches have their
pros and cons which is why we presented both." 
When I wrote it in my comments, I was referring to the sentence quoted in point
4). I.e.: approach one - including the interfering parameters in the univariate and
multivariate regression analyses; and approach two: correcting for the upper
limit of normal. However, the authors, as it was discussed above, did not present
the results of the univariate and multivariate regression analyses using ferritin as
a continuous variable like Chen et al did.
Considering the immediately preceding sentence the authors probably meant that
they performed comparison between fibrotic and non-fibrotic patients and also
carried out ROC analysis using both absolute and corrected ferritin levels. But
this is also confusing without explaining what the mentioned pros and cons are in
this case. Furthermore, the authors also mentioned the logarithmic
transformation which made it even less clear what they were talking about.
I suggest that the logarithmically transformed ferritin level be omitted from the
comparative analysis, and instead of the quoted sentence, simply state that the
authors believe that the results obtained using ULN-corrected ferritin levels are
more valid than the results obtained using the absolute values, but both is
presented for fair validation.
6) The manuscript contains several grammatical errors. Please perform a
grammar check!
Publons Reviewer Recognition
. Springer Nature can send verification of this
review directly to Publons (a subsidiary of Clarivate Analytics). If you would
like to take advantage of this service, please click on the “Yes” option below.
Your name, email address, title of the reviewed manuscript, name of the journal,
and date of your review submission (the “Review Data”) will then be transmitted
to Publons after the final decision on the manuscript has been made. If you have
already registered at Publons, they will notify you of the receipt of this review
and update your profile 
as per your settings and their policy. If you are not
registered with Publons, you will receive an email from them asking you to
register in order for them to be able to recognize your review on your new
profile page. Publons may use the Review Data to generate derivative metadata
for the benefit of Publons and you as a reviewer, carefully considering the
sensitivity of such information. For example, Publons may verify your record as
a reviewer by updating your profile published on its webservice if you have
registered for such service or help editors to identify candidate reviewers. Please
find the details of processing in Publons’ privacy policy
https://publons.com/about/terms
No
Declaration of competing interests
Please complete a declaration of competing
interests, considering the following questions:
1
. 
Have you in the past five years received reimbursements, fees, funding, or
salary from an organisation that may in any way gain or lose financially
from the publication of this manuscript, either now or in the future?
2
. 
Do you hold any stocks or shares in an organisation that may in any way
gain or lose financially from the publication of this manuscript, either now
or in the future?
3
. 
Do you hold or are you currently applying for any patents relating to the
content of the manuscript?
4
. 
Have you received reimbursements, fees, funding, or salary from an
organization that holds or has applied for patents relating to the content of
the manuscript?
5
. 
Do you have any other financial competing interests?
6
. 
Do you have any non-financial competing interests in relation to this
paper?
If you can answer no to all of the above, write 'I declare that I have no competing
interests' below. If your reply is yes to any, please give details below.
I declare that I have no competing interests.
Reviewer Publication Consent.
 I agree for my report to be made available
under an Open Access Creative Commons CC-BY License (
http://creativecommons.org/licenses/by/4.0
) if this manuscript is accepted for
publication. Any comments that I do not wish to be included in the published
report have been included as confidential comments to the editor, which will not
be published.
If you are not happy for us to publish this report, please contact the
editorial office before completing the review.
If you wish, you can include your
name in your published report. Please note you must decide whether to include
your name at the start of the process and confirm this decision whenever
prompted. If you change your decision later, we will not be able to publish your
name.
I agree to the terms of the CC-BY 4.0 license; please 
do not
 publish my name
with my report. (default)
Is the study design appropriate to answer the research question (including the use
of appropriate controls), and are the conclusions supported by the evidence
presented?
Yes
Are the methods sufficiently described to allow the study to be repeated?
Yes
Is the use of statistics and treatment of uncertainties appropriate?
Yes
Is the presentation of the work clear?
No
Are the images in this manuscript (including electrophoretic gels and blots) free
from apparent manipulation?
Yes
assistant