BACKGROUND: Lupus nephritis (LN) is a common and severe complication of systemic lupus erythematosus (SLE), with approximately 40% of patients with SLE developing LN. Even with treatment, 10%-30% of patients will progress to end-stage renal disease (ESRD). Although many studies have assessed the clinical value of low disease activity in LN, the economic implications are less defined. OBJECTIVE: To evaluate treatment utilization and health care costs associated with active disease, low disease activity, and ESRD in patients with LN. METHODS: A retrospective analysis of Optum pharmacy and medical claims data from 2015 to 2019 was performed and included patients with a diagnosis of SLE (International Classification of Diseases, Ninth Revision or Tenth Revision codes 710.0 or M32, respectively) and additional prespecified criteria for LN. Total health care payer costs for medical and pharmacy services and treatment utilization for commonly prescribed medications were determined for periods of low disease activity, active disease, or ESRD. RESULTS: A total of 21,251 patients (mean age 60.3 years; 87% female; 55% White patients and 18% Black patients) with a mean follow-up period of 30.6 months were included; the majority of patients had active disease (67.3%), followed by low disease activity (51.3%), and ESRD (10.5%). Glucocorticoids were used 2 times more often and mycophenolate mofetil was used 4 times more often in patients with active disease vs low disease activity. Glucocorticoids, mycophenolate mofetil, and tacrolimus were more commonly used in patients with ESRD vs those with low disease activity. Mean medical costs were $4,777 per month in active disease and $18,084 per month in ESRD vs $2,523 per month in low disease activity. CONCLUSIONS: Treatment burden and costs are high for patients with active disease and ESRD in LN. Treatments that allow patients to achieve and maintain low disease activity may help improve patient outcomes and reduce medication use and overall health care costs. DISCLOSURES: Maria Dall'Era and Kenneth Kalunian are consultants of Aurinia Pharmaceuticals. Eric Turowski, Vanessa Birardi, Neil Solomons, Simrat Randhawa, and Paola Mina-Osorio are employees and stockholders of Aurinia Pharmaceuticals. Michael Eaddy is a former employee of Xcenda, LLC. Augustina Ogbonnaya and Eileen Farrelly are employees of Xcenda, LLC, which was contracted by Aurinia Pharmaceuticals to assist in the conduct of this study and the writing of this manuscript. Aurinia Pharmaceuticals provided funding for this study and the preparation of the manuscript. Aurinia Pharmaceuticals had a role in writing the report and decision to submit for publication.