Background/Purpose: The role of repeat renal biopsy (RRBx) in lupus nephritis (LN) to guide treatment or predict prognosis is not fully understood. We assessed the association between histopathological changes and clinical outcomes across renal biopsies.

Methods: A retrospective cohort study of 99 patients with biopsy confirmed lupus nephritis (LN), and 39 (39.4%) patients [mean age 29.2 ± 11.0 years; 89.7% female] who had at least one RRBx (median of 2 renal biopsies; interquartile range: 2, 3) for evaluation of persistent/current symptoms. Renal specimens were assessed by ISN classification (Class I and II grouped as mild disease, Class III + IV as proliferative disease, and Class V as membranous proliferative disease), NIH Activity (0-24) and Chronicity (0-12) indices and immunofluorescence findings (0-3) with data on clinical characteristics, serology, medication, disease activity (Systemic Lupus Erythematosus Disease Activity Index – 2K (SLEDAI-2K)), organ damage (SLICC Damage Index (SDI)) at biopsy recorded. Study endpoints included the doubling of serum creatinine, requirement for renal replacement therapy (RRT), and mortality.

Outcomes were assessed comparatively across biopsy events with non-parametric and Chi-square tests; and, logistic regression quantified the odds of study endpoints.

Results: Compared to patients without repeated biopsies; at the initial biopsy, RRBx patients were younger (29 vs 36 years, p=0.026) and, more likely to be lymphopenic (79.5% vs 60.0%, p=0.04) and had “Full house IF findings” (89.5% vs 62.2%, p=0.03). Patients had similar median proteinuria level (300 vs 257, p=0.70) and SLEDAI scores (13 vs 12, p=0.19). RRBx (n=39) occurred 2.95 years (IQR 1.20, 6.10) after the index biopsy; and, clinical characteristics, laboratory levels and SLEDAI scores were similar to the index biopsy data. Class switching occurred in 9 (23%) patients; with Class worsening in 6 and improvement in 3 (p=0.04). NIH Activity Index was not significantly different from the index biopsy; however, Glomerular Sclerosis (0 vs 1), Interstitial Fibrosis (0 vs 1), and the NIH Chronicity Index (1 vs 2) had worsened at the repeat biopsy, all p< 0.01. Increasing Cellular Crescents increased the odds of RRT [OR 1.7 (95%CI: 1.0, 2.8) p=0.049], and the doubling of serum creatinine at last follow-up [OR 2.0 (95%CI 1.0, 4.00), p=0.05]. Increasing NIH Chronicity Index increased the odds of doubling of creatinine at last follow-up [OR 3.6 (95%CI 1.1, 12.3), p=0.04]. There was no impact of histological findings on repeat biopsy on mortality.

Conclusion: Patients with LN with a RRBx showed low rates of ISN Class switching within 3 years, and NIH Activity Index remained unchanged across biopsies; suggesting that repeat biopsies had little impact on disease management. In contrast, NIH Chronicity Index scores were increased and associated with worse renal outcome.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/utility-of-repeat-renal-biopsies-in-patients-with-lupus-nephritis-in-western-australia/