Background/Purpose: The pathophysiology and the content of treatment differ between International Society of Nephrology/Renal Pathology Society (ISN/RPS) class III/IV lupus nephritis (LN) and class V LN. However, the differences in clinical manifestations have not been revealed in detail between class III/IV LN and class V LN. Moreover, predictive factors for the response to induction therapy and the maintenance of remission have not been sufficiently investigated in class V LN. The aim of this study was to clarify the clinical manifestations and predictive factors for the response to induction therapy and the maintenance of remission in class V LN compared with class III/IV LN.

Methods: 48 patients with ISN/RPS class III/IV LN and 23 patients with class V LN were consecutively enrolled at our institute from 2001 to 2010. Clinical manifestations, autoantibodies, and treatment outcomes were analyzed and compared between two subsets. We investigated the predictive factors for the response to induction therapy and the maintenance of remission.

Results: The disease duration was significantly longer (P = 0.0024), and complement component 3 was significantly higher (P = 0.0055) in the class V LN subset. The frequency of anti-dsDNA Ab positivity did not differ between two subsets. Anti-U1snRNP Ab and anti-Sm Ab positivity were significantly higher (P = 0.0054 and P = 0.012, respectively) in the class V LN subset. Patients who were anti-dsDNA Ab-positive and anti-U1snRNP Ab-negative experienced significantly more frequent complications with class III/IV LN (odds ratio 5.1, confidence interval [CI] 1.5-17.6, P = 0.010). In contrast, patients who were anti-dsDNA Ab-negative and anti-U1snRNP Ab-positive experienced significantly more frequent complications with class V LN (odds ratio 6.5, CI 1.2-35.5, P = 0.015). The combined complete and partial remission rate exhibited no significant differentiation between two subsets (82.6% in the class V LN subset and 73.3% in the class III/IV LN subset). In the non-remission subset with class V LN, the quantification of 24-hour proteinuria on induction therapy was significantly higher (P < 0.0001) than in the remission subset with class V LN. Based on the multivariate analysis, the quantification of 24-hour proteinuria was an independent predictive factor for remission in class V LN. The relapse rate exhibited no significant differentiation between two subsets (42.1% in the class V LN subset and 30.3% in the class III/IV LN subset). In the relapse subset with class V LN, the disease duration was significantly longer and the frequency of anti-Sm Ab positivity was higher than in the maintained remission subset with class V LN. Based on the multivariate analysis, the disease duration was an independent predictive factor for the maintenance of remission in class V LN.

Conclusion: LN patients who were anti-U1snRNP/Sm Ab-positive experienced more frequent complications with class V LN. In class V LN, the increased quantification of proteinuria and the longer disease duration on induction therapy were attributed to non-responder and relapsing populations, respectively. Early intervention may improve the rate of the maintenance of remission in class V LN.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/clinical-manifestations-and-predictive-factors-for-response-to-induction-therapy-and-maintenance-of-remission-in-isnrps-class-v-lupus-nephritis/