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During the congress, E-Posters will be accessible to all participants on the congress website 24/7, as well as in the E-poster stations in the congress center.
Preparing your E-Poster
Please review the E-Poster format requirements carefully when preparing your E-Poster. Should your E-Poster not meet the mentioned requirements, it may not be displayed as described above.
E-Poster Submission Deadline
Please prepare and upload your E-Poster no later than March 14, 2026 11.59PM CET. After this date, you will no longer be able to prepare and upload your E-poster and it will not be displayed and accessible on the congress website.
Please follow the instructions below to input your abstract title.
Abstract titles should be brief and reflect the content of the abstract.
Renal biopsy provides essential information for diagnosing kidney diseases and predicting prognosis. Although cortical indices such as the interstitial fibrosis and tubular atrophy (IFTA) score are well recognized as prognostic markers, pathological changes in the renal medulla have been less investigated. In our routine diagnostic practice, we observed considerable variation in medullary fibrosis, inflammatory infiltration, and cast formation. We hypothesized that these medullary findings might reflect distinct pathological processes and could be associated with renal prognosis. This study aimed to clarify whether medullary pathology provides additional prognostic information beyond established cortical parameters.
We retrospectively analyzed 1,136 patients who underwent native kidney biopsy at Okayama University Hospital between 2011 and 2023. After excluding patients younger than 18 years, with an estimated glomerular filtration rate (eGFR) <15 mL/min/1.73 m², or with insufficient medullary tissue, 488 patients were included. Medullary fibrosis, inflammatory cell infiltration, and cast formation were semi-quantitatively scored on a 0–2 scale. The primary endpoint was a composite renal outcome, defined as ≥40% decline in eGFR or initiation of renal replacement therapy. Kaplan-Meier analyses and multivariate Cox regression models were used to evaluate associations between medullary findings and renal outcomes, adjusting for age, eGFR, urinary protein, and IFTA score. Predictive accuracy was evaluated using Harrell’s C-index.
The mean eGFR was 60.9 ± 26.3 mL/min/1.73 m², and the median urinary protein excretion was 1.1 g/gCr (IQR: 0.4–3.1). During a median follow-up of 2.3 years, 112 patients (23.0%) reached the renal endpoint. Kaplan-Meier analyses revealed that both medullary fibrosis and cast formation were significantly associated with adverse renal outcomes, similarly to the IFTA score, whereas medullary inflammatory infiltration showed no significant association. Multivariate Cox regression models adjusted for known risk factors including age, urinary protein, and eGFR revealed that medullary fibrosis (hazard ratio [HR] 1.32; 95% confidence interval [CI] 1.01–1.71) and cast formation (HR 1.70; 95% CI 1.28–2.24) remained independently associated with renal prognosis. Notably, cast formation retained statistical significance even after additional adjusting for IFTA (HR 1.64; 95% CI 1.21–2.21). Furthermore, the inclusion of cast formation into a model containing established prognostic indicators improved the predictive accuracy for renal outcomes (Harrell’s C-index: from 0.638 to 0.655; +0.017), suggesting its independent prognostic value, supporting its independent prognostic value. Ordinal logistic regression analysis showed that cast formation was negatively correlated with eGFR and positively associated with the IFTA score, but not with urinary protein excretion or pathologic urinary casts, suggesting that medullary cast formation may reflect localized tubular stress or intratubular obstruction, rather than glomerular impairment.
Incorporating medullary findings, particularly fibrosis and cast formation, into renal biopsy assessment may enhance the prediction of renal outcomes beyond conventional cortical parameters.
