Kidney Failure Attributed to Immunoglobulin A Nephropathy: A USRDS Retrospective Cohort Study of Epidemiology, Treatment Modalities, and Economic Burden.

ABSTRACT

Rationale & Objective: This study describes the epidemiology, characteristics, and outcomes of patients with immunoglobulin A nephropathy (IgAN)-attributed kidney failure in the US Renal Data System (USRDS) from 2008 to 2018, including health care resource utilization and costs among patients with Medicare-linked data. Study Design: Retrospective cohort study. Setting & Population Patients with IgAN-attributed kidney failure in the USRDS. Outcomes: Prevalence/incidence, clinical/demographic characteristics, time to kidney transplant, and health care resource utilization and costs. Analytical Approach: Patients with IgAN as primary cause of kidney failure (IgAN cohort) were followed from USRDS registration (index date) until data end/death. Prevalence/incidence were calculated per 1,000,000 US persons. Demographic and clinical characteristics at index and treatment modality during follow-up were summarized. Time from index to kidney transplant was assessed using Kaplan-Meier and competing risk analyses. Health care resource utilization and health care costs were reported among patients with 1 year Medicare Part A+B coverage postindex, including or excluding those who died (Medicare Coverage and 1-year Medicare Coverage subgroups, respectively). Results: The IgAN cohort, Medicare Coverage, and 1-year Medicare Coverage subgroups included 10,101, 1,696, and 1,510 patients, respectively. Mean annual period prevalence and incidence of IgAN-attributed kidney failure were 39.3 and 2.9 per 1,000,000 US persons, respectively. Initial treatment was in-center hemodialysis (63.1%) or kidney transplant (15.1%). Year 1 and 5 kidney transplant rates were 5% and 17%, respectively, accounting for competing risk of death. In the Medicare Coverage and 1-year Medicare Coverage subgroups, 74.4% and 72.3%, respectively, required inpatient admission, 67.3% and 64.4%, respectively, visited the emergency room, and mean total health care costs were $6,293 (SD $6,934) and $5,284 ($3,455), respectively, per-patient-per-month in the year postindex. Limitations: Drug costs may be underestimated as Medicare Part D coverage was not required; kidney acquisition costs were unavailable. Conclusions: IgAN-attributed kidney failure is associated with substantial clinical and economic burdens. Novel therapies for IgAN that delay kidney failure are needed.

This study of patients in the United States Renal Data System (USRDS) observed fluctuating incidence and increasing prevalence of immunoglobulin A nephropathy (IgAN)-attributed kidney failure from 2008 to 2018. Patients experienced a high clinical burden, with 63% receiving in-center dialysis and over 15% receiving transplantation as initial therapy. In the first year after USRDS registration, nearly three-quarters of patients with Medicare coverage required hospitalization, and around two-thirds visited the emergency room. The total annual health care costs were >$63,000 per patient with IgAN-attributed kidney failure, underscoring the high economic burden of this disorder and currently available treatments. Novel therapies for IgAN are needed to delay or prevent the need for costly dialysis and transplantation after kidney failure.