Long-term prognosis of pure membranous lupus nephritis: a comparison with proliferative lupus nephritis in Japan.

BACKGROUND

Membranous lupus nephritis (MLN), a distinct subtype of lupus nephritis (LN), is generally associated with more favorable outcomes than proliferative LN (PLN). However, clinical data regarding pure MLN are limited. We investigated the prognosis of patients with pure MLN in Japan.

METHODS

We performed a sub-analysis of a previously reported nationwide retrospective cohort study of patients with LN in Japan. This study included patients who underwent renal biopsy between 2007 and 2012. Patients with pure MLN (Class V, n = 90) were compared to those with PLN (Class III/IV ± V, n = 362) over a median follow-up period of 5 years. The primary outcome was defined as a 50% increase in serum creatinine (S-Cr) levels.

RESULTS

The renal and patient outcomes of the pure MLN and PLN groups were as follows: A ≥ 50% increase in S-Cr occurred in 12.2 vs. 16.3% of patients. Doubling of S-Cr or progression to end-stage kidney disease (ESKD) occurred in 4.4 vs. 8.6%, ESKD alone in 2.2 vs. 3.0%, and all-cause mortality in 7.9 vs. 5.5%. After adjusting for age, sex, baseline renal function, proteinuria, and the use of mycophenolate mofetil or intravenous cyclophosphamide, no significant differences in renal outcomes were observed between groups (hazard ratio 0.564; 95% confidence interval 0.272-1.170; P = 0.124).

CONCLUSION

In this nationwide Japanese cohort, no statistically significant differences in renal outcomes were observed between pure MLN and PLN. Further research is needed to explore strategies to improve outcomes in pure MLN.