Kidney Week

Abstract: FR-PO976

NIH Activity and Chronicity Indices in Lupus Nephritis: A Critical Analysis

Session Information

• Pathology and Lab Medicine - 1
  October 25, 2024 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Pathology and Lab Medicine

• 1800 Pathology and Lab Medicine

Authors

• Querin, Valentina, Department of Biomedical, Experimental and Clinical Sciences "Mario Serio", University of Florence, Florence, Italy

Valentina Querin, MD

• Ravaglia, Fiammetta, Nephrology and Dialysis Unit, Santo Stefano Hospital, Prato, Italy

Fiammetta Ravaglia, MD

• Vaglio, Augusto, Department of Biomedical, Experimental and Clinical Sciences "Mario Serio", University of Florence, Florence, Italy

Augusto Vaglio, MD, PhD

• Bajema, Ingeborg M., Universitair Medisch Centrum Groningen Pathologie en Medische Biologie, Groningen, Netherlands

Ingeborg M. Bajema, MD, PhD

Background

Inclusion of NIH activity and chronicity indices (AI & CI) in the ISN/RPS classification of lupus nephritis (LN) aims to provide a more precise characterization of the amount of active/chronic lesions next to the lupus class. AI is based on 6 lesions (range 0-24) and CI on 4 lesions (range 0-12). We here report how the AI and CI values vary in a large multicenter cohort; which lesions in particular determine the index; and what their relation is to lupus class.

Methods

We collected 86 LN kidney biopsies from 2 international centers, excluding those with <10 scorable glomeruli or with a concomitant glomerular disease. We calculated the NIH AI and CI according to the 2018 ISN/RPS classification revision. We used Pearson’s coefficient to explore correlations and One-way ANOVA to analyze AI and CI distribution in the classes.

Results

More than 90% of the biopsies showed an AI <10 (4.5±3.7) and a CI <8 (2.6±2.7). Class IV (±V) had the highest AI, classes I/II had an AI of 0. Endocapillary hypercellularity was the most common active lesion (table), showing the strongest correlation with neutrophils (r=0.71, p<0.001). Cellular crescents correlated with fibrinoid necrosis and interstitial inflammation (r=0.317, p=003; r=0.415, p<0.001). There were no differences over classes in CI distribution. Interstitial fibrosis, tubular atrophy and glomerulosclerosis were related to each other (p<0.001) but not to fibrous crescents.

Conclusion

In this cohort, AI and CI scores were medium-low and rarely reached the highest values. Endocapillary hypercellularity was the most common lesion driving AI score. It is crucial to reassess if the lesions included in AI and CI reflect the actual activity and chronicity of LN. Investigating potential modifications of the indices may lead to a more balanced and accurate scoring system.