Long-term outcomes of initial therapy for idiopathic membranous nephropathy.

BACKGROUND: The objective of this study is to determine whether initial steroid therapy is actually effective for the treatment of iMN, and we examined a 40% reduction in estimated glomerular filtration rate (eGFR) and remission rates.

METHODS: This was a retrospective study between 1993 and 2013. First, we divided patients with iMN having a urinary protein level of ≥1 g/gCre into two groups: those who had received steroid therapy (Group S1 ; n = 52) within 6 months of diagnosis and those who had received supportive therapy (Group H1 ; n = 31). Second, we compared 20 cases using propensity score matching (Group S2 , Group H2 ). Third, we compared patients with a urinary protein level of 1-3.5 g/gCre (Group S3 , n = 18; Group H3 , n = 19) and those with a urinary protein level ≥3.5 g/gCre (Group S4 , n = 34; Group H4 , n = 12). The primary endpoint was a 40% reduction in eGFR, and the secondary endpoint was the achievement of complete remission (CR).

RESULTS: In Group S1 and Group H1 , a 40% reduction in the eGFR was observed at the end of 5 years in 18 and 17% of the patients, respectively (P = 0.93); at the end of 10 years, these rates had increased to 43% and 50%, respectively (P = 0.88). The CR rates at the end of 5 years were 58% and 32%, respectively (P = 0.02), while the rates at 10 years were 65 and 39%, respectively (P = 0.02). No difference in renal outcomes was observed between Group S1 and Group H1 . No significant differences were observed between Group S2 and Group H2 , between Group S3 and Group H3 , or between Group S4 and Group H4 .

CONCLUSION: Initial steroid therapy is not superior to supportive care within the first 6 months after diagnosis in terms of a 40% reduction in eGFR.