Remission of proteinuria under therapeutic intervention and the renal outcomes in Japanese patients with lupus nephritis class III and IV

Background: Recent studies have identified the significance of proteinuria levels after initial induction therapies on the renal outcomes in patients with proliferative lupus nephritis, but the issue has not been evaluated in Japanese patients. Methods: Based on the ISN/RPS classification, only patients diagnosed with lupus nephritis class III or IV were included. The remission of proteinuria 12 months after diagnosis, as well as the clinicopathological features at diagnosis, on renal outcomes was examined retrospectively. Renal progression was defined as a 50% decrease in the estimated glomerular filtration rate or the development of end-stage renal disease. Results: This study included 82 Japanese patients with a median follow-up period of seven years. Although all patients received intensive induction therapy, 15 patients (18%) showed progression. Proteinuric remission 12 months after diagnosis predicted a good renal outcome by multivariate analysis. A receiver-operating characteristic analysis of 38 patients whose quantitative urinary protein excretion levels at 12 months were available for analysis showed that a cut-off value of 0.8 g/day predicted renal progression most effectively. Neither the renal function nor proteinuria level at diagnosis were associated with the renal outcomes. Conclusion: In Japanese patients with lupus nephritis class III or IV, proteinuria levels after 12 months under intensive therapy predicted renal outcomes more accurately than did factors identified at diagnosis.