Lessons from a specialized lupus clinic: Presentation and damage outcomes in inception vs. prevalent lupus nephritis cohorts.

OBJECTIVES: This study aimed to compare clinical presentations and damage outcomes of lupus nephritis (LN) between patients enrolled early in their systemic lupus erythematosus (SLE) disease course (inception cohort, within one year of disease diagnosis) and those referred later (prevalent cohort). METHODS: We analyzed 526 patients from a longitudinal specialized lupus clinic, focusing on their initial documented LN event, and classified them as inception (n = 246) or prevalent (n = 280) cohorts. Baseline demographics, renal parameters, serologies, histopathology, and treatments were compared. Primary outcomes included a composite renal damage outcome (end-stage kidney disease or a sustained ≥40% eGFR decline) and extra-renal damage accrual (increase in non-renal SLICC/ACR Damage Index [SDI]). Cox proportional hazards models adjusted for confounders assessed associations between cohort status and outcomes. RESULTS: Baseline renal function and LN histologic class were similar between cohorts, though the prevalent group had a higher chronicity index (median 3.0 vs. 2.0, p < 0.01) and more frequent immunosuppressive use (251/280 [89.6%] vs. 200/246 [81.3%], p = 0.01). Renal damage outcomes did not significantly differ between cohorts over a median follow-up of 8.3 years, occurring in 46/244 inception patients [18.9%] and 63/275 prevalent patients [22.9%] (p = 0.32; adjusted HR 1.00, p = 0.99). However, inception cohort patients showed a significantly reduced risk of extra-renal damage accrual (adjusted HR 0.67, p = 0.04). CONCLUSIONS: Renal and non-renal damage are highly prevalent in LN patients. Extra-renal damage is greater in the prevalent cohort, likely reflecting prior disease activity and higher cumulative exposure to immunosuppressive therapies, particularly glucocorticoids, before clinic entry.