1. Categorization of the diabetic nephropathy by Tervaert classification in clinical setting
Hospital de Santo António – CHP, Portugal
Patholo
Filipa Moreno*, Ana Pinho**, Renata Dias*,
Ramon Vizcaino*
*Anatomic Pathology Department – Santo Antonio Hospital, Oporto, Portugal
**Nephrology Department – Faro Hospital, Faro, Portugal

2. Diabetic Nephropathy
Diabetic Nephopathy (DN) is the most common cause of end-stage renal disease (ESRD)
The percentage of patients with ESRD who have Diabetes Mellitus, specially Type II patients, have increseased over the past decade
The incidence of Diabetes Mellitus is rising world wide
It is estimated that 20-40% of all diabetic patients will develop diabetic nephropathy

3. What is the Diabetic Nephropathy?
Clinical syndrome
Persistente proteinuria
Hypertension
Progressive decline in renal function
Pathologic renal
lesions
Diabetic microangiopathy –  of basement membrane (BM) material
Difuse glomerulosclerosis – difuse  in mesangial matrix and thickening of the capillary walls
Nodular glomerulosclerosis – Kimmelstiel-Wilson lesions
Insudative lesions – hyalinosis
Atubular glomeruli
Difuse linear reaction for IgG along the BM

4. Diabetic Nephropathy Diagnostic histopathologic lesions Glomerular
Thickening of glomerular basement membrane (GBM)
Mesangial expansion
Nodular glomerulosclerosis (Kimmelstiel-Wilson lesions)
Interstitial
Thickening of tubular basement membrane (TBM)
Arteriolar hyalinosis
Although the most important structural changes occur in the glomeruli, concomitantly and in proportion to the degree of glomerulopathy, arterioles, tubules and interstitium also develop morphological lesions, the most

5. Tervaert’s Pathologic Classification of Diabetic Nephropathy
“Our aim, commissioned by the Research Committee of the Renal Pathology Society, was to develop a consensus classification combining type I and type II diabetic nephropathies”
Jornal of the American Society of Nephrology, 21: , 2010
The team decided to classify DN due to type I and type II diabetes toguether because there is substantial overlap in histologic lesions and renal complications
Similar histologic lesions
Similar renal complications
Type I DN
Type II DN

6. Tervaert’s Pathologic Classification of Diabetic Nephropathy
They created a classification scheme that diveded the Diabetic nephopathy lesions in four progressive classes, based on glomerular lesions

7. Glomerular Basement Membrane Thickening
Class I
Glomerular Basement Membrane Thickening
Biopsy shows no or only mild, nonspecific changes by light microscopy
Changes do not meet the criteria of classes II through IV
Absence of mesangial expansion, nodular KW lesions and glomerulosclerosis
GBM, measured with EM is, on average
Thicker than 430 nm in males
Thicker than 395 nm in females
Class I – H & E 400x

8. Class II Mesangial Expansion II a – Mild II b – Severe
Class II a – PAS 400x
Mild or severe mesangial expansion, not meeting the criteria for class II or IV
Mesangial expansion – increase in extracellular material in the mesangium such that the width of the interspace exceeds two mesangial cell nuclei in at least two glomerular lobules
Mild – expanded mesangial area < mean area of a capillary lumen
Severe - expanded mesangial area > mean area of a capillary lumen
Class II b – PAS 400x

9. Nodular Sclerosis – Kimmelstiel-Wilson lesions.
Class III
Nodular Sclerosis – Kimmelstiel-Wilson lesions.
At least one convincing Kimmelstiel-Wilson lesion is found
The biopsy specimen does not have more than 50% global glomerulosclerosis (Class III)
Kimmelstiel-Wilson lesion – focal, lobular, round to oval mesangial lesions with an acellular, hyaline/matrix core, rounded peripherally by sparse, crescent-shaped mesangial nuclei
Class III – PAS 400x

10. Advanced Diabetic Glomerulosclerosis
Class IV
Advanced Diabetic Glomerulosclerosis
Class IV – PAS 400x
Advanced DN
More than 50% global glomerulosclerosis
The is clinical or pathological evidence that the sclerosis is attributable to DN

11. Tervaert’s Pathologic Classification of Diabetic Nephropathy
Travaert and his team also sugested a separate evaluation for interstitial and vascular lesions

12. Objective
To assess the reliability and prognostic value of the Tervaert’s pathologic classification of diabetic nephropathy in renal biopsies performed on type 2 diabetes mellitus patients with an atypical clinical presentation of renal disease

13. Intermediate Pathologist
Methods
Study design
Population
Single-center study in a tertiary referral hospital for renal pathology
Retrospective evaluation of 710 consecutive renal biopsies
Selection of Diabetic Nephropathy (DM) positive biopsies
In our study, a senior pathologist, na intermediate and a junior pathologist retrospectively evaluated consecutive renal biopsies, selecting the DN positive ones and aplying the Travaert classification on them, blinded for inter-observer and clinical outcome.
Population Represented?
Single-center study
Tertiary referral center for renal pathology
Exposure & Comparison Allocated well – Measurements accurate? Blind or Objective? Well Maintained?
Participants in each group
Follow-up
Completed follow-up?
Drop-outs / lost during follow-up?
Exposure & Comparison
Senior Pathologist
>10 years experience
(A – Gold standard)
Intermediate Pathologist
3 years experience
(B)
Junior Pathologist
1st year of practice
(C)
Blinded inter-observer and blinded for clinical outcome categorization of DM biopsies

14. Methods Categorization with Tervaert Classification
To aplly the classification, we followed the flow chart sugested by Travaert to evaluate the glomaruli in each biopsy.
We also classifed the interstitial lesions with the previously shown table.

15. Methods Study analysis Outcomes Time Results Primary: Start dialysis
Secondary: Death (censored death not related with diabetic disease)
Time
Between biopsy data and outcome (Cohort retrospective)
Results
Testing of the different baseline characteristics among classes
Evaluation of Tervaert’s classification reproducibility
Survival analysis by classes - Kaplan Meier

16. Characterization of the Population
Results
Characterization of the Population
Table 1 Baseline data at the moment of biopsy**
Among 710 RN revised, there were 22 pureDN and 8 DN coexisting with other types of pathology (mixedDN). The mixedDN forms were associated to IgA nephropathy (3), transplant glomerulopathy (2), light chain disease (1), amyloidosis (1) or HIV-Associated Nephropathy (1).
** All patients had Type II diabetes mellitus

17. Results Reproducibility
Table 2 Senior Pathologist (A – Gold standard) vs Intermediate Pathologist experience (B)
(A)
Classes II
III IV
(B) 9 1 14 - -  1  3
kappa= 0.85
As it was previously reported, the inter-observer reproducibility for Terveaert classification was good (K = 0.82)
Table 3 Senior Pathologist (A – Gold standard) vs Junior Pathologist experience (C)
(A)
Classes II
III IV
(C) 8 1 2 13 -  - 2  3 
kappa=0.79
Global Kappa – 0.82

18. Results Renal survival
Figure 1 Kaplain Meier curves by Tervaert Classification DN
The estimated 5-year renal survival rate was 98.4% in Classes II, 54.3% in Class III, and 36.2% in Class IV (p=0.04).
At 5 years follow-up
Renal survival
II= 98.4%
III= 54.3%
IV= 36.2%

19. Discussion Study validity Recruitment Allocation Maintenance
Blind or objective assessment of outcomes
Results analysis
Recruitment: was the setting / EP appropriate given the study goals &/or the reviewer’s interests? If relevant, were participants representative of the EP? Could the results be generalised to relevant populations? This should be able to be determined from risk factor/prognostic profile of participants. In prognostic studies – were participants at similar stage in progression of their disease or condition?
Allocation: how well were participants allocated to E&C? If a trial were they randomised to E&C? ! If randomised, was allocation concealed (i.e. knowledge of group (EG or CG) participants allocated to
concealed from staff & participants until after allocation documented)? Was randomization successful (i.e. EG & CG similar after randomisation – were baseline characteristics similar in each group)?
!If not randomised (observational study) were measurements of E&C accurate & similarly for EG & CG? Were differences between EG & CG documented Maintenance: did participants remain in the groups (EG or CG) they were initially allocated to? Blinding: were participants / investigators blind to whether participants were exposed to E or C?
Compliance: % participants allocated to EG (or CG) who remained exposed to E (or C) during study? Contamination: % participants allocated to CG who crossover to EG (& visa versa if CG an exposure)? Co- intervention: other significant interventions received unequally by EG&CG during follow-up? Completeness of follow-up: was it high & similar in EG & CG?
Blind assessment of outcomes: were outcome assessors unaware if participants in EG or CG? or Objective assessment of outcomes. eg. biopsies; x-rays, validated questionnaires?

20. Recruitment The setting was appropriate, given the study goals.
The participants were at a similar stage in terms of progression of their disease.
The participants were not representative of all Tervaert’s Pathologic Classification of Diabetic Nephropathy with pure nephropathy diabetic

21. Problems
Recruitment
Biopsies are performed only when clinical course is not typical for diabetic nephropathy
The biopsies do not represent the pathologic range of DN in type II diabetic patients
The biopsies only represent patients with atypical clinical course
A wide range of non-diabetic renal disease may be present

22. Allocation
The participants were consistently allocated to Tervaert’s classes
The measurements of baseline data were accurate and similar for the different classes
The differences between classes were documented at the biopsy date
Recruitment: was the setting / EP appropriate given the study goals &/or the reviewer’s interests? If relevant, were participants representative of the EP? Could the results be generalised to relevant populations? This should be able to be determined from risk factor/prognostic profile of participants. In prognostic studies – were participants at similar stage in progression of their disease or condition?
Allocation: how well were participants allocated to E&C? If a trial were they randomised to E&C? ! If randomised, was allocation concealed (i.e. knowledge of group (EG or CG) participants allocated to
concealed from staff & participants until after allocation documented)? Was randomization successful (i.e. EG & CG similar after randomisation – were baseline characteristics similar in each group)?
!If not randomised (observational study) were measurements of E&C accurate & similarly for EG & CG? Were differences between EG & CG documented Maintenance: did participants remain in the groups (EG or CG) they were initially allocated to? Blinding: were participants / investigators blind to whether participants were exposed to E or C?
Compliance: % participants allocated to EG (or CG) who remained exposed to E (or C) during study? Contamination: % participants allocated to CG who crossover to EG (& visa versa if CG an exposure)? Co- intervention: other significant interventions received unequally by EG&CG during follow-up? Completeness of follow-up: was it high & similar in EG & CG?
Blind assessment of outcomes: were outcome assessors unaware if participants in EG or CG? or Objective assessment of outcomes. eg. biopsies; x-rays, validated questionnaires?

23. Problems
Allocation
The pathologic findings in diabetic nephropathy differ substantially between type I and type II diabetic patients
Kidney lesions underlying renal dysfunction are more heterogeneous in type II patients
In Type I patients, the most important renal structure changes occur in the glomeruli
Type II patients are more complex and only a minority have histopathological patterns similar to the typical DN of Type I patients

24. Problems
Allocation
The mechanisms underlying the associations between cause, natural history and histopathological pattern in the DN of Type II patients are inadequately defined
Only a percentage of samples from type II diabetic patients with proteinuria have typical diabetic glomerulopathy
The association between the clinic and pathologic findings is not always linear in Type II patients
Differences found between class IIb and III may only be due to different pathogenic processes and not progression of disease

25. Maintenance
The participants remained in the groups they were initially allocated to
The participants / investigators were blind to participants categorization with Tervaert Classification /clinical baseline data, respectively
Clinical co-intervention during the follow-up period was unknown
Completeness of follow-up was high and similar in allocated groups
Compliance and contamination problems were probably absent
Recruitment: was the setting / EP appropriate given the study goals &/or the reviewer’s interests? If relevant, were participants representative of the EP? Could the results be generalised to relevant populations? This should be able to be determined from risk factor/prognostic profile of participants. In prognostic studies – were participants at similar stage in progression of their disease or condition?
Allocation: how well were participants allocated to E&C? If a trial were they randomised to E&C? ! If randomised, was allocation concealed (i.e. knowledge of group (EG or CG) participants allocated to
concealed from staff & participants until after allocation documented)? Was randomization successful (i.e. EG & CG similar after randomisation – were baseline characteristics similar in each group)?
!If not randomised (observational study) were measurements of E&C accurate & similarly for EG & CG? Were differences between EG & CG documented Maintenance: did participants remain in the groups (EG or CG) they were initially allocated to? Blinding: were participants / investigators blind to whether participants were exposed to E or C?
Compliance: % participants allocated to EG (or CG) who remained exposed to E (or C) during study? Contamination: % participants allocated to CG who crossover to EG (& visa versa if CG an exposure)? Co- intervention: other significant interventions received unequally by EG&CG during follow-up? Completeness of follow-up: was it high & similar in EG & CG?
Blind assessment of outcomes: were outcome assessors unaware if participants in EG or CG? or Objective assessment of outcomes. eg. biopsies; x-rays, validated questionnaires?

26. Assessment of outcomes
The outcome assessors were unaware of participants categorization with Tervaert Classification (Blind assessment of outcomes)
The assessment of outcomes was objective (start dialysis date)
The death not related with diabetic disease was censored
Recruitment: was the setting / EP appropriate given the study goals &/or the reviewer’s interests? If relevant, were participants representative of the EP? Could the results be generalised to relevant populations? This should be able to be determined from risk factor/prognostic profile of participants. In prognostic studies – were participants at similar stage in progression of their disease or condition?
Allocation: how well were participants allocated to E&C? If a trial were they randomised to E&C? ! If randomised, was allocation concealed (i.e. knowledge of group (EG or CG) participants allocated to
concealed from staff & participants until after allocation documented)? Was randomization successful (i.e. EG & CG similar after randomisation – were baseline characteristics similar in each group)?
!If not randomised (observational study) were measurements of E&C accurate & similarly for EG & CG? Were differences between EG & CG documented Maintenance: did participants remain in the groups (EG or CG) they were initially allocated to? Blinding: were participants / investigators blind to whether participants were exposed to E or C?
Compliance: % participants allocated to EG (or CG) who remained exposed to E (or C) during study? Contamination: % participants allocated to CG who crossover to EG (& visa versa if CG an exposure)? Co- intervention: other significant interventions received unequally by EG&CG during follow-up? Completeness of follow-up: was it high & similar in EG & CG?
Blind assessment of outcomes: were outcome assessors unaware if participants in EG or CG? or Objective assessment of outcomes. eg. biopsies; x-rays, validated questionnaires?

27. Results
Survival analyses include all participants allocated by exposure factor
Reasonable precision (low confidence limits)
There was consistency with other studies
No adjusted analyses was needed for confounders
Recruitment: was the setting / EP appropriate given the study goals &/or the reviewer’s interests? If relevant, were participants representative of the EP? Could the results be generalised to relevant populations? This should be able to be determined from risk factor/prognostic profile of participants. In prognostic studies – were participants at similar stage in progression of their disease or condition?
Allocation: how well were participants allocated to E&C? If a trial were they randomised to E&C? ! If randomised, was allocation concealed (i.e. knowledge of group (EG or CG) participants allocated to
concealed from staff & participants until after allocation documented)? Was randomization successful (i.e. EG & CG similar after randomisation – were baseline characteristics similar in each group)?
!If not randomised (observational study) were measurements of E&C accurate & similarly for EG & CG? Were differences between EG & CG documented Maintenance: did participants remain in the groups (EG or CG) they were initially allocated to? Blinding: were participants / investigators blind to whether participants were exposed to E or C?
Compliance: % participants allocated to EG (or CG) who remained exposed to E (or C) during study? Contamination: % participants allocated to CG who crossover to EG (& visa versa if CG an exposure)? Co- intervention: other significant interventions received unequally by EG&CG during follow-up? Completeness of follow-up: was it high & similar in EG & CG?
Blind assessment of outcomes: were outcome assessors unaware if participants in EG or CG? or Objective assessment of outcomes. eg. biopsies; x-rays, validated questionnaires?
Mazzucco, G. et al. Different patterns of renal damage in type 2 diabetes melitus: a multicentric study on 393 biopsies. AJKD 39 (4), (2002)
Se Won Oh et al. Clinical implications of pathologic diagnosis and classification for diabetic nephropathy. Diabetes research and clinical practice –424 (2012)

28. Conclusions
In our study, Tervaert classification proved to be user friendly, accurate and clinically useful
There was a good inter-observer reproducibility
A uniform and consistent classification of DN will improve the communication between renal pathologists and clinicians, allowing better clinical management.
Our findings corroborate the results from experimental centers
Larger and more significant trials are therefore recommended

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