Lupus Nephritis (LN) is one of the most severe complications that can occur in patients with Systemic Lupus Erythematosus (SLE) as it increases the risk of renal failure, comorbidity and death. As with SLE, there is a significant impact of ethnicity on LN severity and outcome. Objectives: To investigate the impact of ethnicity of LN presentation and health outcomes in a tertiary referral centre in Western Australia. Methods: Single centre retrospective cohort study of 104 patients with biopsy

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... nfirmed lupus nephritis (LN) collating clinical characteristics, renal histopathology, serology, medication use, disease activity (Systemic Lupus Erythematosus Disease Activity Index -2K (SLEDAI-2K)), organ damage (SLICC-Damage Index (SDI)), and clinical outcomes from index biopsy event to the last visit. Outcomes included the high serum creatinine (≥150 umol/L), low eGFR (<50%), the need for renal replacement therapy (RRT), and death. Outcomes were assessed across ethnicity with comparative statistics, Chi-square, and survival analysis. Results: Asian (n=17, 16.3%), Caucasian (n=79, 76.0%) and Indigenous (n=8, 7.7%) patients were similar for age (p=0.149), gender (p=0.309) and SLEDAI-2K (8.5 vs. 9.0 vs. 13.0, p=0.897), non-renal SLEDAI-2K (10.5 vs 2 vs. 1, p=0.528). Time to biopsy from the initial SLE diagnosis was shorter in Asian and Indigenous patients (p=0.055). At the index biopsy, ethnic groups were similar for WHO Class distribution (predominantly Classes 3 and 4, p=0.345) and clinical signs of renal disease (the presence of haematuria, proteinuria, pyuria and/or red cell casts) (p=0.874). Indigenous patients trended towards higher creatinine (66.0 vs 71.0 vs. 101.5, p=0.214), lower eGFR (60% vs. 60% vs. 32.5%, p=0.076), lower C3 (0.67 vs. 0.65 vs. 0.47g/L, p=0.375) and C4 (0.15 vs 0.12 vs 0.03g/L, p=0.272), and higher anti-dsDNA antibody levels (16.0 vs 26.5 vs 520.0, p=0.81), albeit non-significantly (due to low numbers). At the last follow-up, 6.4 years (IQR 3.8, 12.4) after the index biopsy, 10%, 30% and 12.5% of Asian, Caucasian and Indigenous patients had high serum creatinine levels (≥150 umol/L) (p=0.434) and 10%, 28.9% and 25.0% had low eGFR (<50%) respectively. Chronic renal replacement therapy (RRT) was needed in 0%, 5.1%, and 12.5%, respectively (p=0.386), while death occurred in 0%, 8.7% and 25.0%, respectively (p=0.115). Indigenous patients had the poorest survival rates at 1, 5 and 10 years compared to Caucasian patients (p=0.002). Conclusions: This interim analysis demonstrated that Asian patients had a better prognosis regarding serum creatinine, eGFR, commencement of RRT and mortality, compared to Caucasian and Indigenous patients. Indigenous patients were both over-represented in this cohort and showed poorer prognosis in terms of RRT and mortality rates compared to Asian or Caucasian patients in WA.