POS0732 SHORT AND LONG-TERM OUTCOMES OF PATIENTS WITH PURE MEMBRANOUS LUPUS NEPHRITIS COMPARED TO PATIENTS WITH PROLIFERATIVE DISEASE
Authors: Z. Touma, F. Kharouf, Q. LI, L. Whittall-Garcia, D. D. Gladman
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> Lupus nephritis (LN) occurs in approximately 50% of patients with systemic lupus erythematosus (SLE). Class V, membranous LN (MLN), is thought to have a more benign course than proliferative disease. <h3>Objectives:</h3> We aimed to determine the differences in short and long-term outcomes between patients with MLN and Proliferative LN (PLN). <h3>Methods:</h3> This is a retrospective analysis of patients followed prospectively at a Lupus cohort. We included patients with biopsy-proven MLN and PLN. First recorded biopsies were analyzed. The median [interquartile range] follow-up time for both groups was 8.3 [4.0, 13.8] years. The short-term outcome, complete proteinuria recovery (CPR), was defined as proteinuria &lt;500 mg/24h. Long-term outcomes included a sustained ≥40% reduction in baseline eGFR, end-stage renal disease (ESRD) (eGFR &lt;15 mL/min/1.73 m<sup>2</sup>, dialysis, or renal transplant), and death. The outcomes were compared between the MLN and PLN groups. The time to short and long-term outcomes was assessed with Kaplan-Meier (KM) curves. <h3>Results:</h3> Of 215 patients included in this study, 51 had pure MLN, and 164 had PLN. The latter group included 120 isolated proliferative and 44 mixed biopsies (Class III+V or IV+V). Baseline characteristics are shown in Figure 1. The median age of our cohort was 33.2 [26.7, 42.9] years, with 187 (87%) females, 111 (52%) Caucasians, and 48 (22.4%) Black. Patients with MLN were more likely to be of Black race (37.3% vs. 17.7%, p=0.01). They presented with lower median serum creatinine (69 [54.0, 86.5] vs. 77 [62.0, 100.5] μmol/L (p=0.01)) and higher median eGFR (94.3 [74.7, 129.8] vs. 83.5 [59.1, 108.3] mL/min/1.73 m<sup>2</sup> (p=0.01)). Low complement (43.1% vs. 76.2%, p&lt;0.001) and positive anti-dsDNA (48% vs. 74.4%, p&lt;0.001) were more common in PLN vs. MLN. Median proteinuria level was higher in the MLN group (3.0 [1.1, 4.1] vs. 2.4 [1.3, 3.7] g/day (p=0.52)). The median SLEDAI-2K scores (12.0 [8.0, 15.0] vs. 16.0 [12.8, 22.0] (p&lt;0.001)) and NIH activity and chronicity indices (0.0 [0.0, 1.0] vs. 6.0 [3.0, 9.0] (p&lt;0.001) and 2.0 [0.0, 2.75] vs. 3.0 [1.0, 4.0] (p=0.007), respectively) were higher in PLN. The average daily corticosteroid dose during the first year (18.3 vs. 23.9 mg/day (p&lt;0.001)) was also higher in PLN. Mycophenolate mofetil (103 [47.9%]) and azathioprine (89 [41.4%]) were the most used immunosuppressives. Cyclophosphamide use was more common in PLN (3.9% vs. 15.9%, p=0.048). The use of other therapies (tacrolimus and cyclosporine for instance) was more common in MLN (21.6% vs. 9.8%, p=0.048). <b>Short-term outcomes</b>. At 1 year, 18 (35%) MLN patients and 69 (42.1%) PLN patients achieved CPR (p=0.49). At 2 years, 25 (49.0%) MLN patients achieved this outcome, compared to 87 (53%) PLN patients (p=0.73). The median time to CPR was comparable between the two groups (1.3 [0.7, 3.2] for MLN vs. 1.0 [0.5, 2.6] for PLN in years, p=0.50). <b>Long-term outcomes</b>. Nine (17.6%) patients in the MLN group had a sustained ≥40% reduction in baseline eGFR, whereas 38 (23.3%) PLN patients met this outcome (p=0.51). Median time to outcome was similar (6.6 [3.0, 14.4] for MLN vs. 6.6 [2.4, 11.2] for PLN in years, p=0.30). Four (7.8%) MLN and 24 (14.7%) PLN patients (p=0.30) developed ESRD. Time to ESRD was comparable (8.4 [4.0, 14.5] for MLN vs. 7.2 [3.4, 12.1] for PLN in years (p=0.20)). Death occurred in 4 (7.8%) MLN and 23 (14.0%) PLN patients (p=0.36), with a similar time to outcome (8.4 [4.0, 14.5] for MLN vs. 8.3 [4.0, 12.8] for PLN in years, (p=0.20)). Figure 2 A-D shows KM curves representing the time to short and long-term outcomes of MLN and PLN patients. <h3>Conclusion:</h3> The resolution of proteinuria in LN is slow. MLN is not a benign disease and may be associated with significant deterioration of kidney function, ESRD, and death. <h3>REFERENCES:</h3> <b>NIL.</b> <h3>Acknowledgements:</h3> The Toronto Lupus Program is supported by Lupus Ontario, the Schroeder Arthritis Institute and donations from the Kathi and Peter Kaiser family and the Lou and Marissa Rocca family. Dr. Zahi Touma is supported by the University of Toronto Department of Medicine and the Dr. Murray Urowitz Chair in Lupus Research. <h3>Disclosure of Interests:</h3> <b>None declared.</b>