IgA Nephropathy (IGAN) in Adults: A Retrospective Analysis of US Prevalence and Impacts of Proteinuria and Kidney Function Decline on Healthcare Resource Utilization (HRU) and Costs

ABSTRACT

Objectives: Globally, IgAN is the most common primary glomerulonephritis and, if not controlled, results in progression to end-stage kidney disease (ESKD). This study examines the US prevalence of IgAN and the impacts of proteinuria and kidney function decline to ESKD on HRU and costs. Methods: Descriptive, retrospective analysis based on Optum® de-identified Market Clarity and proprietary Natural Language Processed (NLP) Data (2007-2020). Inclusion criteria ≥2 IgAN NLP terms within 180 days at least 30 days apart without associated negation terms. For patients with available claims data (subset of the prevalence cohort), HRU/costs analyses were completed (exclusions pregnancy, cancer, COVID-19). All costs were normalized/discounted and adjusted to 2020 USD using the Consumer Price Index. Results: Estimated standardized US prevalence of IgAN (2016–2019) is 130.17 per 1,000,000 based on US Census Bureau data. Among 253 patients with proteinuria data in the HRU/costs cohort, 45% had high-risk proteinuria (≥1.0 g/g). HRU (mean outpatient visits, 1.93 vs 4.24;pharmacy claims, 2.69 vs 3.84) and total costs (mean $1,408 vs $3,721), all per-patient-per month (PPPM), are higher (p<0.05) among patients with elevated proteinuria (<1.0 g/g [n=139] vs ≥1.0 g/g [n=114]). Advancing chronic kidney disease stage to ESKD (stage I [n=171] vs stage III [n=171] vs ESKD [n=148] PPPM outpatient visits, mean 1.84 vs 2.70 vs 7.40;pharmacy claims, 2.30 vs 3.68 vs 4.97;PPPM total costs, mean $1,455 vs $2,499 vs $8,479) was also associated with significantly higher HRU and costs (p<0.05). Conclusions: A substantial proportion of patients with IgAN have elevated proteinuria. Elevated proteinuria and progression to ESKD are associated with a significant HRU and cost burden. Treatments that reduce proteinuria and prevent decline in kidney function have the potential to reduce the resource intensity and economic burden of IgAN.