Healthcare Resource Utilization and Costs in Newly Diagnosed Moderate-to-Severe Primary Membranous Nephropathy

Abstract

Background: Primary membranous nephropathy (PMN) is a rare autoimmune glomerular disease representing one of the leading causes of nephrotic syndrome in adults, with approximately one-third of patients progressing to end-stage renal disease (ESRD). The clinical burden of PMN is substantial, encompassing frequent outpatient visits, laboratory monitoring, and immunosuppressive treatment for moderate-to-severe disease. However, real-world evidence characterizing costs and healthcare resource utilization (HRU) amongst patients with incident PMN, particularly those with moderate-to-severe disease in which immunosuppressive therapy is indicated, remains limited. Objective: To estimate the HRU and costs attributable to moderate-to-severe PMN in the year following initiation of immunosuppressant treatment among commercially insured patients in the US. Methods: We conducted a retrospective cohort study using the Merative MarketscanTM health insurance claims database. Incident PMN patients that initiated an immunosuppressive treatment (a surrogate for diagnosis of moderate-to-severe PMN) within 1 year of diagnosis were identified between January 1st, 2016 and March 31st, 2023. Non-PMN controls were matched 3:1 to PMN cases. Two-part models were used to model costs and count outcomes where possible, and logit models were used to estimate the probability of ≥1 ED visit or hospitalization during the 1-year follow-up period. Bootstrapping was performed to generate 95% confidence intervals (CI). Results: In the year following initiation of immunosuppressant treatment, PMN patients incurred an additional $33,356 (95% CI: $23,581-$48,861) in total medical costs on average, which was largely comprised of an increase in outpatient (OP) costs [$27,055 (95% CI: $19,657-$39,083)]. PMN patients were also twice as likely to have ≥1 ED visit (relative risk (RR) 2.19, 95% CI: 1.43-3.32) and 2.71 times more likely to have ≥1 hospitalization (RR 2.71, 95% CI: 1.21-6.04). Conclusion: We found that PMN patients incurred significantly greater overall and outpatient medical costs in comparison to matched controls. As this analysis was limited to a 1-year follow-up to capture outcomes immediately following treatment initiation, costs and resource utilization associated with continued progression of PMN may not be captured. Additional research is needed to assess clinical features of PMN that may be associated with increased costs and HRU and to describe the components of OP care that most significantly contribute to increased costs of care in PMN patients.