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Abstract: PO1584

IgA Nephropathy Histopathology and Long-Term Renal Prognosis

Session Information

Category: Glomerular Diseases

  • 1203 Glomerular Diseases: Clinical, Outcomes, and Trials

Authors

  • Maddy, Nora Claire Elizabeth, Walter Reed National Military Medical Center, Bethesda, Maryland, United States
  • Nee, Robert, Walter Reed National Military Medical Center, Bethesda, Maryland, United States
  • Gordon, Sarah M., Walter Reed National Military Medical Center, Bethesda, Maryland, United States
  • Olson, Stephen W., Walter Reed National Military Medical Center, Bethesda, Maryland, United States
Background

The Oxford Classification established the mesangial hypercellularity (M), Endocapillary hypercellularity (E), segmental sclerosis (S), Tubulointerstitial fibrosis (T), and crescents (C) score as an important prognostic tool for IgA nephropathy (IgAN). However, these studies did not investigate the impact of complement 3 (C3) immunofluorescence (IF) staining or interstitial inflammation (iI) on long term renal outcomes, nor evaluate an ethnically diverse population which included African Americans.

Methods

We queried the military health system (MHS) by ICD-9/10 codes to identify potential IgA nephropathy cases. We then reviewed the electronic medical record to find those with biopsy-proven IgA nephropathy. Prespecified clinical data was collected to include MEST-C scores, iI, and C3 IF. Primary outcomes included >50% decline in estimated glomerular filtration rates (eGFR), chronic kidney disease (CKD) with eGFR <60ml/min/1.73m2, and end-stage kidney disease (ESKD).

Results

172 patients were identified with a mean follow-up of 11 years. Mean age was 32 years; 77.9% male; 64.5% White, 9.9% Black, and 12.2% Asian/Pacific Islanders. C3 IF ≥2+ was significantly associated with ESKD (p=0.03) and >50% decline in eGFR (p=0.02). iI ≥ 15% was significant for ESKD (p=0.003), CKD (p=0.01), and >50% decline in GFR (p=0.01). T and C scores were significant for ESKD , CKD, and >50% decline in GFR (all p<0.001). S score was significant for ESKD (p=0.022) and CKD (p=0.009). E score was significant for CKD (p=0.003). M score was not significant for any of the primary outcomes.

Conclusion

We present histopathology associated long term renal outcome data for the most ethnically diverse IgAN cohort with the longest follow up to date in such a population. Our data suggests that degree of C3 staining on IF and amount of interstitial inflammation could augment the prognostic accuracy of the MEST-C score. In addition, it supports the theory that IgA immune complexes activate the alternative complement pathway which drives significant interstitial inflammation ultimately resulting in tubular atrophy and interstitial fibrosis.

Disclaimer: The views expressed are those of the authors and do not reflect official policy of the Department of the Army/Navy/Air Force, Department of Defense, or United States government.