Membranous nephropathy in systemic lupus erythematosus: long-term outcome and prognostic factors of 103 patients

Objectives: The objective of this study was to evaluate the clinical features, course, outcome, and prognostic indicators in lupus membranous nephritis (LMN) and to compare data of "pure" LMN vs "mixed" forms. Methods: We retrospectively examined medical records and kidney biopsies of 103 patients with a diagnosis of LMN. Results: Sixty-seven patients had "pure" LMN and 36 had "mixed" forms. Patients with mixed LMN had more frequent nephrotic syndrome (66.6 vs 44.7%, P = 0.05), low C3 (83.3 vs 62.6%, P = 0.05) and C4 (80.5 vs 52.2%, P = 0.005), anti-DNA positivity (86.0 vs 62.6%, P = 0.03), and a tendency toward a lower creatinine clearance (93 +/- 29 vs 112 +/- 50 mL/min, P = 0.07). Moreover, mixed membranous nephritis had a higher activity and chronicity index (6.5 +/- 2.1 vs 1.4 +/- 2.03, P = 0.005 and 2.4 +/- 1.7 vs 1.4 +/- 1.8, P = 0.0001, respectively). Methylprednisolone pulses and immunosuppressive therapy were more often used in patients with mixed forms (86.1 vs 60.6%, P = 0.016 and 83.3 vs 57.5%, P = 0.008, respectively). After a mean follow-up of 156.5 +/- 104.5 months, there was no difference in the 2 subgroups concerning the number of patients achieving remission and patient/renal survival (94.5 vs 94.0% and 85.8 vs 86% at 10 years). At multivariate analysis, serum creatinine at presentation (P = 0.0013), chronicity index (P = 0.007), failure of achieving remission (P = 0.000001), and occurrence of nephritic flares (P = 0.00167) were independent predictors of chronic renal insufficiency. Conclusions: Despite the differences in clinical and histological presentation, a therapy tailored on the grounds of clinical and histological features may reduce the differences in the outcome of white patients with mixed and pure membranous nephritis.