The value of repeat kidney biopsy in quiescent Argentinian lupus nephritis patients

Background: The duration of maintenance therapy after induction therapy for lupus nephritis has not been rigorously established. A common practice is to maintain immunosuppression for 1-2 years after complete remission, and longer for partial remission. The present work addresses whether a repeat kidney biopsy might be informative in deciding who should continue immunosuppression after complete or partial remission. Methods: The practice in a large Buenos Aires nephrology unit is to repeat a kidney biopsy before finalizing the decision to withdraw or continue immunosuppression. This work reports on a cohort of 25 Hispanic patients that had two or more kidney biopsies, the last occurring after at least 24 months of clinically quiescent disease. Results: Despite normalization of serum creatinine and reduction of proteinuria to <500 mg/d, 30% of patients still had significant activity at the last biopsy. Conversely, 60% of patients with ongoing proteinuria (500-1000 mg/d), or stable but abnormal serum creatinine, had no activity by biopsy. Univariate association analyses demonstrated that improvement in the activity index (AI) of the last biopsy was associated with choice of induction therapy (cyclophosphamide or mycophenolate), improvement in serum creatinine over the first six months of treatment, and improvement in complement component C4. By multivariate regression analyses, two AI prediction models emerged. Cyclophosphamide plus change in serum creatinine or cyclophosphamide plus change in C4 accounted for 50% of the improvement in AI. Conclusion: These data suggest that a repeat biopsy may be useful in making the decision to withdraw or continue maintenance immunosuppression.