Background/Purpose: Lupus nephritis (LN) is a major manifestation which develops in more than 50% of patients with systemic lupus erythematosus (SLE), and is also a primary risk factor for morbidity and mortality in these patients. The revision of International Society of Nephrology/Renal Pathology Society (ISN/RPS) classification guidelines for lupus nephritis (LN) was suggested by a working group, who recommended a modified National Institute of Health (NIH) activity and chronicity scoring system to evaluate active and chronic LN lesions. However, whether this approach was useful for estimating long-term prognosis for LN patients is unclear.

Methods: We conducted a retrospective cohort study in Japanese subjects with biopsy-proven LN, between 1977 and 2022. Pathologic lesions were evaluated based on ISN/RPS 2003 classifications and the modified NIH scoring system. Patients were grouped by activity index (low, 0–5; moderate, 6–11; high, 12–24), and chronicity index (low, 0–2; moderate, 3–5; high, 6–12). The primary outcome was a composite of end-stage kidney disease (ESKD) or all-cause death, and the secondary outcome was ESKD alone.

Results: Seventy subjects with a median age of 31 years were included. Median follow-up period was 11.3 years. For the activity index, Kaplan–Meier analysis showed that the survival rate of the primary outcome decreased with a higher activity index (log-rank trend p = 0.026) . Multivariable analysis, adjusted by age and serum creatinine, did not show any significant relationship to the activity index. For the chronicity index, Kaplan–Meier analysis showed that the survival rate of the primary outcome decreased with a higher chronicity index (log-rank trend p< 0.001). Multivariable analysis, adjusted by age and serum creatinine, revealed that moderate (HR 6.18, 95% CI 1.15 to 33.3; p = 0.034) and high chronicity indices (HR 20.33, 95% CI 1.14 to 360.50; p = 0.04) were significant risk factors for the primary outcome. Consistent results with the primary outcome were determined by Kaplan–Meier and univariable analysis.

Conclusion: Moderate and high chronicity indices were associated with an increased ESKD risk for LN. This modified NIH activity and chronicity scoring system may help physicians predict long-term prognosis for patients with LN.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/high-chronicity-index-of-the-modified-nih-national-institute-of-health-scoring-system-of-lupus-nephritis-is-associated-with-increased-risk-of-end-stage-kidney-disease-a-retrospective-single-center/