Restrictive use of immunosuppressive treatment in patients with idiopathic membranous nephropathy: high renal survival in a large patient cohort

Background: Immunosuppressive treatment initiated at an early stage in patients with idiopathic membranous nephropathy (iMN) improves renal survival. Treatment should ideally be restricted to high-risk patients. Aim: To evaluate the efficacy of a restrictive immunosuppressive treatment strategy for patients with iMN. Design: Prospective cohort study evaluating a predefined treatment protocol. Methods: From 1988, we adopted a restrictive treatment strategy: immunosuppressive treatment, mainly consisting of cyclophosphamide and steroids, was advised only in patients with renal insufficiency or severe intolerable nephrotic syndrome. We evaluated this strategy in a large patient cohort. To exclude any bias, we included all adult patients with iMN biopsied in the study period with a serum creatinine (Scr) < 135 mumol/l, a proteinuria greater than or equal to 3.0 g/day and/or a serum albumin (Salb) less than or equal to 30 g/l at the time of biopsy. Analysis was according to the intention-to-treat principle. Results: We studied 69 patients. At the time of biopsy, mean age was 51 years, Scr 90 mumol/l, Salb 23 g/l and proteinuria 6.7 g/day. Average follow-up was 5.5 years. Thus far 33 (48%) patients have received immunosuppressive therapy, mainly because of renal insufficiency (n = 24). Status at the end of follow-up was: complete remission n = 22 (32%), partial remission n = 24 (35%), nephrotic syndrome n = 15 (22%), persistent proteinuria n = 1 (1.4%), ESRD n = 6 (8.7%), death n = 1 (1.4%; due to bladder carcinoma after cyclophosphamide therapy). Patient survival was 100% at 5 and 7 years. Renal survival was 94% at 5 years and 88% at 7 years. Discussion: In patients with iMN, a restrictive treatment policy assures a favourable prognosis, while preventing exposure to immunosuppressive therapy in >50% of the patients.