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Kidney Week

Abstract: SA-PO972

Impact of Kidney Biopsy Findings Including Oxford MEST-C Scores on Kidney Outcomes in IgA Vasculitis Nephritis (IgAVN): A Study of the International IgA Nephropathy Network

Session Information

Category: Glomerular Diseases

  • 1402 Glomerular Diseases: Clinical, Outcomes, and Trials

Authors

  • Barbour, Sean, The University of British Columbia Faculty of Medicine, Vancouver, British Columbia, Canada
  • Coppo, Rosanna, Fondazione Ricerca Molinette, Torino, Piemonte, Italy
  • Er, Lee, BC Provincial Renal Agency, Vancouver, British Columbia, Canada
  • Pillebout, Evangeline, Hopital Saint-Louis, Paris, Île-de-France, France
  • Haas, Mark, Cedars-Sinai Medical Center, Los Angeles, California, United States
Background

Nephritis is a common manifestation of IgAV and is morphologically indistinguishable from IgA nephropathy (IgAN). However, while MEST-C scores are predictive of outcomes in IgAN, their value in IgAVN has not been widely studied.

Methods

Biopsies from 361 patients with IgAVN (262 children, 99 adults) from 17 centers in N. America, Europe and Asia were independently scored by 3 pathologists. Median time from clinical onset to biopsy was 2.0 mo, median post-biopsy follow-up was 2.7 y, 309 (85.6%) patients received immunosuppression (IS) during follow-up. As few patients developed ESKD or >30% eGFR decline, Latent Class Mixed Models (LCMM) were used to analyze eGFR trajectory post-biopsy in patients treated with IS. Association of clinical and histologic parameters with the different classes of eGFR trajectory was examined by logistic regression.

Results

Two classes were identified by LCMM (Figure), one with initial improvement in eGFR followed by a more notable decline (Class 1, n = 91) and one with stable disease (Class 2, n = 218). Among MEST-C scores, only E1 was predictive of Class 1 by multivariable analysis (OR 2.3; 95% CI 1.1,4.5); other scores were not although only 4.5% of patients had T>0. Other predictors of Class 1 were age <18 y, male sex, lower eGFR at biopsy, and extrarenal, non-cutaneous disease. Fibrous crescents were predictive of Class 2.

Conclusion

The clinical course of biopsied and treated patients with IgAVN is determined by active lesions, notably endocapillary hypercellularity (E1) which is not part of the ISKDC classification for IgAVN. The results support including MEST-C scores in biopsy reports of IgAVN. Patients with IgAVN, even those with initial therapeutic response, require long-term follow-up due to risk of late renal function decline.

Classes of eGFR trajectory identified by LCMM. Shaded areas are confidence intervals.

Funding

  • Private Foundation Support