Background: This study was designed to review the prognosis and the predictors of renal outcome in patients with membranous lupus nephropathy (MLN) with no or mild mesangial proliferation.
Methods: The medical records of patients (n=66) with biopsy-proven MLN, WHO class VA, and class VB without any past history of proliferative lupus nephropathy (PLN) were reviewed retrospectively.
Results: The mean follow-up was 6.9+/-0.2 years and renal survival at 5 and 10 years was 97+/-2 and 88+/-6%. Twenty-nine patients underwent a second renal biopsy during follow-up. Fourteen of these patients (21%) had lesions of PLN. Among them, four reached end-stage renal disease (ESRD) despite immunosuppressive treatment. The probability of a transition from MLN to PLN at 10 years was 35+/-8%. Two other patients reached ESRD but did not have repeat renal biopsies and two had biopsy-proven progression to fibrosis. Independent risk factors associated with the doubling of creatinine were transition into PLN and the occurrence of a thrombosis during follow-up. The only predictor of ESRD was the haemoglobin level. PLN was not a predictor of ESRD but the efficient treatment of this form of lupus nephritis prevented that outcome.
Conclusions: With a long follow-up, our study noted a high frequency of transition into PLN in a large cohort of patients with MLN. Steroid usage was not predictive of outcome and did not affect renal survival, a result that must be qualified in light of the highly variable duration of treatments with steroids. The early screening and treatment of PLN is the main benefit of the close follow-up of patients with MLN. Progression to ESRD with only fibrosis remains a rare event.