Banff-based histologic chronicity index is associated with graft failure but has poor interobserver reproducibility
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Updated: Jun 25, 2025
Using a Chemical Biopsy for Graft Quality Assessment
Published on: June 17, 2020
Wei-Chou Lin1, Mei-Chin Wen2, Yong-Chen Hsu3
1Department of Pathology, National Taiwan University Hospital, Taipei, Taiwan.
Insights
The proposed simplified histologic chronicity index (CI) for antibody-mediated rejection (AMR) shows poor interobserver reproducibility, limiting its use as a reliable prognostic tool for kidney allograft failure.
Area of Science:
- Nephrology
- Transplantation Immunology
- Pathology
Background:
- Antibody-mediated rejection (AMR) is a primary cause of chronic kidney allograft damage and failure.
- The Banff classification for AMR diagnosis is complex.
- A simplified Banff-based histologic chronicity index (CI) was proposed but lacks external validation.
Purpose of the Study:
- To assess the interobserver reproducibility of the proposed CI and its components in kidney allograft biopsies.
- To evaluate the association between CI and kidney allograft failure.
- To determine the reliability of proposed CI cut-off values for predicting allograft outcomes.
Main Methods:
- Analysis of 71 kidney allograft biopsies diagnosed with AMR.
- Assessment of interobserver agreement for CI and its components (cg, cv, ct, ci).
- Cox regression and Kaplan-Meier analysis to evaluate CI's association with allograft failure and test cut-off values.
Main Results:
- The CI was associated with allograft failure, but its assessment showed significant variability among pathologists.
- Complete agreement on the proposed CI cut-off (<4 vs. ≥4) was achieved in only 69.0% of biopsies.
- The cg score, a key component of CI, exhibited the lowest interobserver agreement (kappa = 0.281), and the cut-off did not reliably stratify failure risk.
Conclusions:
- The proposed CI has limitations due to poor interobserver reproducibility, impacting its utility as a prognostic tool for AMR.
- Clinicians should exercise caution when interpreting CI and may need to establish personalized cut-off values.
- Further work is required to improve interobserver reproducibility before widespread adoption of CI for AMR management.
Background:
Antibody-mediated rejection (AMR) often leads to chronic kidney allograft damage and is a critical cause of allograft failure. The Banff classification, used to diagnose AMR, has become complex and challenging for clinicians. A Banff-based histologic chronicity index (CI) was recently proposed as a simplified prognostic indicator. Its reliability and reproducibility have not been externally validated.
Methods:
This study investigated 71 kidney allograft biopsies diagnosed with AMR. Interobserver reproducibility of the recently proposed CI and its components (cg, cv, ct, and ci) were assessed. The association between CI and allograft failure was analyzed, and CI cut-off values were evaluated by Cox proportional hazards regression and Kaplan-Meier estimator with log-rank test.
Results:
The study confirmed the association of CI with allograft failure, but also revealed that the assessment of CI varied between pathologists, impacting its reproducibility as a prognostic tool. Only 49 (69.0%) of the biopsies showed complete agreement on the proposed cut-off value of CI < 4 or CI ≥ 4. Furthermore, this cut-off did not reliably stratify allograft failure. Notably, the cg score, which carries significant weight in the CI calculation, had the lowest agreement between observers (kappa = .281).
Conclusions:
While a simplified prognostic indicator for AMR is needed, this study highlights the limitations of CI, particularly its poor interobserver reproducibility. Our findings suggest that clinicians should interpret CI cautiously and consider establishing their own cut-off values. This study underscores the need to address interobserver reproducibility before CI can be widely adopted for AMR management.
