Kidney Pathology and Outcomes in ANCA-Associated Vasculitis: Retrospective Analysis of 85 Patients

Round 1

Reviewer 1 Report

This is an interesting study, however some facts are missing.

Treatment is an important point and at least the authors should look for differences between cyclophosphamide and rituximab. Do the patients receive plasma exchange? What about remission? Is remission achieved in every patient? Does COVID influences treatment?

In the calculation and the figures it is necessary to give the number of the patients at risk for every group. With only a small number of patient results might be more difficult regarding interpretation.

What is the distribution of the patients regarding follow up?

What about creatinine at start of treatment? It might be as good as ARRS regarding outcome. The calculation is missing.

Finally the median follow up of 18 months is low. The authors should wait until 24 months are reached. Moreover, as an endpoint dialysis should be chosen as this is more important for the patients and the physicians.

Author Response

Dear Reviewer,

Thank You so very much for sacrificing Your time and expertise, and reviewing our humble manuscript. We have carefully revised our manuscript and considered Your valuable remarks and suggestions. All changes highlighted in yellow in the revised manuscript

 

• Treatment is an important point and at least the authors should look for differences between cyclophosphamide and rituximab. Do the patients receive plasma exchange? What about remission? Is remission achieved in every patient? Does COVID influences treatment?

We added information about treatment regimens, including plasma exchange use, and data regarding kidney survival for cyclophosphamide, rituximab, and cyclophosphamide switched to rituximab cases, and discussed these results. We also added the number of remissions. Only one patient in our study group got COVID-19 by the end of the study, at that time he was in remission for 9 years, received low-dose steroids and azathioprine, recovered from COVID and still in remission.

• In the calculation and the figures it is necessary to give the number of the patients at risk for every group. With only a small number of patient results might be more difficult regarding interpretation.

We added the number of patients at high, medium and low risk, basing on the ARRS score to the Table 1.

 

• What is the distribution of the patients regarding follow up?

We did not find statistically significant differences in the follow-up distribution between the patients with GPA, MPA and EGPA, and we added this information to the text.

 

• What about creatinine at start of treatment? It might be as good as ARRS regarding outcome. The calculation is missing.

Median serum creatinine in the study group at the start of treatment was 257.0 [171; 528.5] µmol/L, as it is indicated in the results section. We added median creatinine at presentation for each ANCA sub-type to the Table 1; however, we did not analyze serum creatinine at the end of follow-up, because ARRS includes eGFR, calculated using equation, based on serum creatinine.

 

• Finally the median follow up of 18 months is low. The authors should wait until 24 months are reached. Moreover, as an endpoint dialysis should be chosen as this is more important for the patients and the physicians.

Unfortunately, it may take several years to wait until 24 months median follow-up reached, because some of our patients died, started dialysis or were lost for the follow-up, which influenced the calculation of the median follow-up period. We purposely not included months and even years on dialysis into the follow-up period, as our primary goal was to evaluate kidney survival. For this reason, we used kidney death (defined as eGFR < 15 mL/min, including, but not limited to the immediate need for dialysis treatment) as an end-point. However, we added the number of patients, started on dialysis to the text.

 

Thank You so very much again for the review, Your comments helped us enormously.

Dear Reviewer,

Thank You so very much for sacrificing Your time and expertise, and reviewing our humble manuscript. We have carefully revised our manuscript and considered Your valuable remarks and suggestions. All changes highlighted in yellow in the revised manuscript

 

• Treatment is an important point and at least the authors should look for differences between cyclophosphamide and rituximab. Do the patients receive plasma exchange? What about remission? Is remission achieved in every patient? Does COVID influences treatment?

We added information about treatment regimens, including plasma exchange use, and data regarding kidney survival for cyclophosphamide, rituximab, and cyclophosphamide switched to rituximab cases, and discussed these results. We also added the number of remissions. Only one patient in our study group got COVID-19 by the end of the study, at that time he was in remission for 9 years, received low-dose steroids and azathioprine, recovered from COVID and still in remission.

• In the calculation and the figures it is necessary to give the number of the patients at risk for every group. With only a small number of patient results might be more difficult regarding interpretation.

We added the number of patients at high, medium and low risk, basing on the ARRS score to the Table 1.

 

• What is the distribution of the patients regarding follow up?

We did not find statistically significant differences in the follow-up distribution between the patients with GPA, MPA and EGPA, and we added this information to the text.

 

• What about creatinine at start of treatment? It might be as good as ARRS regarding outcome. The calculation is missing.

Median serum creatinine in the study group at the start of treatment was 257.0 [171; 528.5] µmol/L, as it is indicated in the results section. We added median creatinine at presentation for each ANCA sub-type to the Table 1; however, we did not analyze serum creatinine at the end of follow-up, because ARRS includes eGFR, calculated using equation, based on serum creatinine.

 

• Finally the median follow up of 18 months is low. The authors should wait until 24 months are reached. Moreover, as an endpoint dialysis should be chosen as this is more important for the patients and the physicians.

Unfortunately, it may take several years to wait until 24 months median follow-up reached, because some of our patients died, started dialysis or were lost for the follow-up, which influenced the calculation of the median follow-up period. We purposely not included months and even years on dialysis into the follow-up period, as our primary goal was to evaluate kidney survival. For this reason, we used kidney death (defined as eGFR < 15 mL/min, including, but not limited to the immediate need for dialysis treatment) as an end-point. However, we added the number of patients, started on dialysis to the text.

 

Thank You so very much again for the review, Your comments helped us enormously.

 

Reviewer 2 Report

Major comments

1. Title and patient selection: a total 8 patients were ANCA-negative. Tin my opinion, it is rather strange to include ANCA-negative patients in this manuscript that is on ANCA-associated vasculitis. Consider to exclude these patients or perform additional analyses excluding these patients.
2. Line 142: In 10 patients the ‘general test for ANCA was performed without identification of ANCA subtype’. Please specify what is meant by ‘general test’. Which test was used – immunofluorescence? Please add this information to the manuscript. If IF is used, the authors probably have information on the fluorescence pattern, C-ANCA versus P-ANCA. Please provide this information.
3. Table 1 now only shows information on the subgroups anti-PR3 and anti-MPO patients. Please add columns for the other 2 groups: the 10 patients that were positive with a ‘general test’ and the 8 ANCA-negative patients.
4. The manuscript would gain enormously in information if the authors would add more information to Table 1, e.g. BVAS, creatinine at diagnosis, biopsy results, results of the 2 classifications. In this way, the differences between the groups will be much more clear.

 

Minor comments

1. The English could be improved. The authors often use a ‘telegram style’ and skip words, e.g. in line 48: regardless of immunosuppressive treatment. And in line 73: group disorders is based … Another example in line 91: … normal glomeruli is found in the patients … Line 109 and 110: … regimens were not included / kidney biopsy were performed … Notably, this style is used throughout the manuscript, so please adapt this throughout the manuscript.  
2. Lines 93 and 94: The observation that biopsies of patients with anti-MPO have more fibrosis and sclerosis was first described by Franssen et al in Kidney Int 1995;47:193-199: Differences between anti-myeloperoxidase and anti-proteinase 3 associated renal disease. Since this is the first and one of the largest biopsy studies in ANCA associated vasculitis, I advise to add this reference.
3. Line 117: BVAS: when was the BVAS scored? At initial diagnosis? Please specify.
4. Line120: what is meant by ‘mixed AAV’? Please specify and give a definition.
5. Line 130: the unit of eGFR is ml/min/1.73 m² I assume that the authors also used this unit.
6. Lines 156 and 157: , should be replaced by . in r=0,303 and p=0,011. This also applies to lines 166 and 182.
7. There is a typo in line 191: ‘subgrops’ should be ‘subgroups’.
8. Line 240: what is meant by OP? in the same line the seems to be a word in the Russian alphabet.
9. Line 244; ‘careers’. Should this be carriers? The same applies to line 255.
10. Line 251: ‘N and T parameters’ may not be clear to readers. Please explain.

 

Author Response

Dear Reviewer,

Thank You so very much for sacrificing Your time and expertise, and reviewing our humble manuscript. We have carefully revised our manuscript and considered Your valuable remarks and suggestions. All changes highlighted in yellow in the revised manuscript

 

Major comments

1. Title and patient selection: a total 8 patients were ANCA-negative. Tin my opinion, it is rather strange to include ANCA-negative patients in this manuscript that is on ANCA-associated vasculitis. Consider to exclude these patients or perform additional analyses excluding these patients.

The term ANCA-negative, or seronegative ANCA disease mentioned in the literature. For example, Ronald Falk and Charles Jennet pointed: “This is with the realization that some patients are ANCA-negative but have a clinically and pathologically identical disease to ANCA-positive patients... If serologic data are known, then the designation could be PR3-ANCA disease, MPO-ANCA disease, or seronegative ANCA disease. Seronegative ANCA disease is conceptually analogous to seronegative systemic lupus erythematosus and seronegative rheumatoid arthritis”

[JASN May 2010, 21 (5) 745-752; DOI: https://doi.org/10.1681/ASN.2009121238]

Moreover, the last UpToDate topic “Clinical spectrum of antineutrophil cytoplasmic autoantibodies” (updated June 29 2021) indicates: “Approximately 90 percent of patients with active, generalized GPA are ANCA positive. However, there is a small subset of patients with active, generalized GPA who do not have ANCA. Thus, the absence of ANCA does not exclude the diagnosis of GPA… ANCA, both PR3 and MPO, have been detected with variable frequencies in patients with EGPA. Although variable from study to study, approximately 50 percent of patients with EGPA are ANCA positive… Some studies suggest the possibility of clinical differences among patients with EGPA who are ANCA positive as opposed to ANCA negative. ANCA-positive patients are more likely to have glomerulonephritis, alveolar hemorrhage, and neurologic disease, whereas ANCA-negative patients are more likely to have cardiac and other pulmonary involvement. However, there is certainly overlap in clinical presentations among patients with and without ANCA”. Given that, we considered our 8 ANCA-negative patients with typical clinical presentation and biopsy-proven pauci-immune glomerulonephritis as eligible for the study. However, we changed the name ANCA-negative to seronegative.

2. Line 142: In 10 patients the ‘general test for ANCA was performed without identification of ANCA subtype’. Please specify what is meant by ‘general test’. Which test was used – immunofluorescence? Please add this information to the manuscript. If IF is used, the authors probably have information on the fluorescence pattern, C-ANCA versus P-ANCA. Please provide this information.

In 10 cases ANCA screening test, using indirect immunofluorescence, was performed, and unfortunately the pattern is not available. We changed “general test” to “screening test”. This information added to the text and to the Table 1.

3. Table 1 now only shows information on the subgroups anti-PR3 and anti-MPO patients. Please add columns for the other 2 groups: the 10 patients that were positive with a ‘general test’ and the 8 ANCA-negative patients.

We modified the Table 1 accordingly.

4. The manuscript would gain enormously in information if the authors would add more information to Table 1, e.g. BVAS, creatinine at diagnosis, biopsy results, results of the 2 classifications. In this way, the differences between the groups will be much more clear.

 We added all these data to the Table 1.

 

Minor comments

1. The English could be improved. The authors often use a ‘telegram style’ and skip words, e.g. in line 48: regardless of immunosuppressive treatment. And in line 73: group disorders is based … Another example in line 91: … normal glomeruli is found in the patients … Line 109 and 110: … regimens were not included / kidney biopsy were performed … Notably, this style is used throughout the manuscript, so please adapt this throughout the manuscript.  

Corrected

2. Lines 93 and 94: The observation that biopsies of patients with anti-MPO have more fibrosis and sclerosis was first described by Franssen et al in Kidney Int 1995;47:193-199: Differences between anti-myeloperoxidase and anti-proteinase 3 associated renal disease. Since this is the first and one of the largest biopsy studies in ANCA associated vasculitis, I advise to add this reference.

This reference is already included and mentioned in the Discussion (number 39, kindly see the References).

3. Line 117: BVAS: when was the BVAS scored? At initial diagnosis? Please specify.

Done

4. Line120: what is meant by ‘mixed AAV’? Please specify and give a definition.

We meant AAV superimposed on IgA vasculitis, corrected

5. Line 130: the unit of eGFR is ml/min/1.73 m² I assume that the authors also used this unit.

Yes, corrected

6. Lines 156 and 157: , should be replaced by . in r=0,303 and p=0,011. This also applies to lines 166 and 182.

Corrected

7. There is a typo in line 191: ‘subgrops’ should be ‘subgroups’.

Corrected

 

8. Line 240: what is meant by OP? in the same line the seems to be a word in the Russian alphabet.

Sorry, it was in Russian indeed. Corrected to RR and CI

9. Line 244; ‘careers’. Should this be carriers? The same applies to line 255.

Corrected

10. Line 251: ‘N and T parameters’ may not be clear to readers. Please explain.

Done

 

Thank You so very much again for the review, Your comments and corrections helped us enormously.

Author Response File: Author Response.pdf

Reviewer 3 Report

This retrospective observational single center study evaluated 121 biopsies in patients with ANCA vasculitis based on the Berden classification and its association concerning the outcome of kidney function.

I would like to see a flow chart including the numbers of patients excluded from the study, and the reasons why they have been excluded. The numbers of figures should be limited to the main message of the manuscript. I would like to see a paragraph discussing the consequences of their findings in future therapeutic decisions. In addition, since the study evaluated biopsies taken from a rather long period (20 years), differences in outcome due to new therapies could be awaited. Are there differences in their reulst between 2000-2010 and the period 2011-2020? Maybe the authors should also check on that.

Author Response

Dear Reviewer,

Thank You so very much for sacrificing Your time and expertise, and reviewing our humble manuscript. We have carefully revised our manuscript and considered Your valuable remarks and suggestions. All changes highlighted in yellow in the revised manuscript

 

• I would like to see a flow chart including the numbers of patients excluded from the study, and the reasons why they have been excluded.

We added a Figure, illustrating the study group selection and the reasons for excluding patients without adequate kidney pathology and with coexistent diseases

 

• The numbers of figures should be limited to the main message of the manuscript.

We removed two Figures, illustrating statistically non-significant results

 

• I would like to see a paragraph discussing the consequences of their findings in future therapeutic decisions.

We supplemented the discussion, pointing that usage of rituximab improves kidney outcomes in the patients with crescentic class according to the Berden’s classification, and that the ARRS is the better predictor of the kidney outcomes regardless the treatment options. 

 

• In addition, since the study evaluated biopsies taken from a rather long period (20 years), differences in outcome due to new therapies could be awaited. Are there differences in their results between 2000-2010 and the period 2011-2020? Maybe the authors should also check on that.

We checked the data and did not find significant differences between these two decades, this information also added to the text.

Thank You so very much again for the review, Your comments helped us enormously.

Round 2

Reviewer 1 Report

No comments. The authors have followed most of the reccomendations. 

Reviewer 2 Report

In my opinion, the authors have adequately addressed al issues.

Reviewer 3 Report

All questions raised have been answered adequately!