Background: Lupus nephritis (LN) significantly contributes to the morbidity and mortality in systemic lupus erythematosus (SLE). Renal biopsy is the gold standard for LN. Given that nephrologists typically conduct these biopsies, it’s intriguing to explore potential differences in biopsy indications and clinical characteristics of LN patients between rheumatology and nephrology departments. The 2019 European League Against Rheumatism (EULAR) guidelines moderately expanded renal biopsy indications [1] ^, yet the extent to which clinicians have adopted these recommendations in practice remains unclear.

Objectives: This study aims to compare the clinical and pathological differences in LN patients treated in Rheumatology and Nephrology departments, and to compare renal biopsy indications before and after 2019, highlighting potential differences in the understanding and application of renal biopsy indications.

Methods: SLE patients who underwent renal biopsy at Peking University First Hospital between January 2011 and July 2024 were included. Demographic data, laboratory parameters, and biopsy findings were collected and analyzed by department (Rheumatology vs. Nephrology) and time periods (pre-2019 and post-2019).

Results: A total of 543 patients with biopsy-proven LN were included, with 195 in rheumatology and 348 in nephrology department. Rheumatology LN patients had longer SLE disease durations and higher prevalence of extrarenal involvement, whereas Nephrology LN patients exhibited more severe renal impairment, reflected by lower eGFR and higher activity index (AI) score. LN pathological types and chronic index (CI) score were similar across departments. The post-2019 group (n=275) showed reduced SLEDAI scores, and a significant decrease in urinary red cells and casts. However, no differences in histological classes or AI/CI scores were observed between pre- and post-2019 groups. Notably, the percentage of isolated proteinuria as an indication for renal biopsy increased after 2019, whereas proteinuria with hematuria and leukocyturia, decreased significantly.

Conclusion: This study highlights significant differences in clinical characteristics, laboratory findings, and renal biopsy indications between Rheumatology and Nephrology departments, reflecting their distinct approaches to LN management. Furthermore, the implementation of the 2019 EULAR guidelines has likely enhanced the emphasis on early detection of renal involvement for renal biopsy indication, particularly isolated proteinuria.

REFERENCES: [1] Fanouriakis A, Kostopoulou M, Cheema K, et al. 2019 Update of the Joint European League Against Rheumatism and European Renal Association-European Dialysis and Transplant Association (EULAR/ERA-EDTA) recommendations for the management of lupus nephritis. Ann Rheum Dis . 2020;79(6):713-723.

Acknowledgements: NIL.

Disclosure of Interests: None declared.

© The Authors 2025. This abstract is an open access article published in Annals of Rheumatic Diseases under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ). Neither EULAR nor the publisher make any representation as to the accuracy of the content. The authors are solely responsible for the content in their abstract including accuracy of the facts, statements, results, conclusion, citing resources etc.