Background/Purpose:

Renal biopsies are considered the gold standard in diagnosing lupus nephritis (LN). ALMS (1), the largest randomized trial in LN, reported the non-inferiority of mycophenolate mofetil (MMF) compared to cyclophosphamide. The mean serum creatinine in this trial was 100micromoles/L. Since its publication, MMF has been standard therapy in proliferative LN, but there may be delays in obtaining a histological diagnosis due to practical considerations. Renal biopsy also has a recognized complication rate. We therefore investigated whether histological findings influenced treatment in patients with SLE and clinical features consistent with LN.

Methods:

Histopathology and renal databases were used to identify all cases of new biopsy-proven active LN, diagnosed between February 2012 and November 2016 and managed at the Barts Lupus Centre (n=62). Demographic and clinical data were collected using case records and pathology systems. LN classes based on glomerular pathology were defined according to the ISN/RPS 2003 classification. Patients were divided into sub groups based on their renal function (eGFR above or below 50 ml/min/1.73m²).

Results: The mean age at LN diagnosis was 37 years (+-13 SD). 55 patients were female (89%) whilst 7 were male (11%). The ethnic distribution was the following: 46% South Asian, 34% Black, and 11% Caucasian. The histological class was either pure proliferative (class III or IV) or mixed proliferative (with additional class V) in 24 cases (39%). 42 (64%) patients had an eGFR > 50mL/min at presentation with a mean albumin and urine PCR of 30 g/dL and 520 mg/mmol respectively. Of this group, 37 patients (88%) received MMF, and only 3 patients were treated with cyclophosphamide (1- clinician decision, 2- severe extra renal manifestations). The remaining two patients received Azathioprine and both had sub-nephrotic proteinuria. At six months, 85% of LN patients were either in partial remission, defined as proteinuria below 200 mg/mmol (44%), or complete remission defined as proteinuria below 50 mg/mmol (41%). The treatment choice was different in the group with eGFR ≤ 50mL/min, with 65% of these patients receiving cyclophosphamide.

Conclusion:

Current guidelines strongly recommend performing a kidney biopsy in every patient presenting with suspected LN. Our findings indicate that in patients with preserved renal function (eGFR > 50mL/min) and significant proteinuria, treatment decision is not influenced by biopsy result. We therefore propose that induction treatment with MMF should not be delayed until a renal biopsy result is available. This study also questions the necessity of baseline histology in LN patients with preserved renal function, as the majority respond to standard therapy, and raises the possibility that biopsy could be reserved for patients who are resistant to induction therapy.

References

(1) Appel GB, Contreras G, Dooley MA, et al. Mycophenolate mofetil versus Cyclophosphamide for induction treatment of lupus nephritis, J Am Soc Nephrol, 2009, vol. 20 (pg. 1103-1112)

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/a-renal-biopsy-should-not-delay-treatment-initiation-in-suspected-lupus-nephritis/