CKD Stage, Proteinuria Tied to Higher HCRU in IgAN

Simple baseline measurements, such as chronic kidney disease (CKD) stage, proteinuria level, and overall comorbidity burden taken at the time of kidney biopsy, can reliably predict how intensively patients with immunoglobulin A nephropathy (IgAN) will use health care resources in the years that follow, according to a retrospective cohort study published in the Journal of Health Economics and Outcomes Research.¹ The findings arrive as a new class of disease-specific IgAN therapies enters the market.²

Patients with IgAN will almost always experience kidney failure during their lifetime. “Kidney failure imposes the greatest burden of illness on patients and economic costs to the health care system,” the authors explained. “However, IgAN can exert considerable impacts on patient quality of life and health care resource utilization (HCRU) earlier in the course of the disease, well before kidney function decline.”

Traditionally, treatment guidelines for IgAN have recommended supportive care, but as treatment options evolve to disease-specific therapies, a better understanding of the patients who will most benefit from novel therapies and intensive management can help create a more accurate cost-benefit analysis of options.

What the Data Show About CKD Stage and Resource Use

Researchers from Kaiser Permanente Southern California analyzed electronic health records and administrative claims data from 612 adults with biopsy-confirmed primary IgAN diagnosed between 2000 and 2021. The study population was racially and ethnically diverse (39.7% Hispanic, 30.9% Asian/Pacific Islander, 23.7% White, and 3.3% Black), which is an important feature given that race and ethnicity are established risk factors for IgAN incidence and progression.

Over an average follow-up of roughly 22 months post biopsy, the team tracked HCRU across 6 categories: emergency department (ED) visits, inpatient stays, outpatient visits, radiology, laboratory services, and medication dispensations. All were expressed as utilization per patient per month (PPPM).

The relationship between CKD severity and resource use was clear and graded. CKD stage G4 was the most advanced kidney function decline captured in the study, and these patients had an aggregate HCRU rate of 2.94 PPPM, significantly higher than those in less advanced stages, who ranged from 1.56 to 2.04 PPPM (P < .01 for all pairwise comparisons). The steepest jump in resource use occurred between stages G3 and G4.

The authors contextualized the clinical significance of these differences, noting that a 0.5 PPPM increase represents 1 additional health care encounter every 2 months. “This is an important finding in CKD, where even small rises signal higher disease burden, worsening stability, greater risk of progression, increased hospital and acute care use, higher costs, and declining quality of life,” they noted.

The cost burden of CKD rises substantially with each stage of progression, with inpatient admissions serving as a major driver even in the early stages of the disease.³ Those dynamics appear equally applicable in IgAN specifically, where the adjusted regression analyses in this study showed that patients with lower kidney function had a significantly higher rate of inpatient visits compared with those in milder CKD stages.¹

Proteinuria Level Adds Independent Predictive Signal

Proteinuria severity told a similar story. Patients with a urine protein creatinine ratio (UPCR) above 2 g/g had an aggregate HCRU of 2.38 PPPM, significantly exceeding each lower proteinuria category (1.70-1.84 PPPM; P < .01). A numerically increasing trend in resource use emerged across all UPCR categories. Higher UPCR was also independently associated with more frequent ED visits in adjusted regression analyses.

A prior retrospective analysis covering a US commercially insured IgAN population similarly found that high-risk proteinuria, defined as at or above 1 gram per day, was associated with more than double the rate of outpatient visits and significantly higher total costs PPPM compared with lower proteinuria, with total monthly costs reaching $3732 versus $1457.⁴

Comorbidity Burden Compounds the Utilization Picture

Beyond kidney-specific markers, the study found that higher scores on the Elixhauser Comorbidity Index—a measure of overall illness burden—were independently associated with greater use of nearly every HCRU category, including outpatient visits, ED encounters, inpatient stays, radiology, laboratory services, and medication dispensations. Patients in CKD stage G4 were more likely to have hypertension (85.9% vs 28.2% in stage G1), diabetes, coronary artery disease, and heart failure, compounding both clinical complexity and resource demands.¹

The comorbidity finding is consistent with broader CKD literature suggesting that patients with concurrent conditions drive disproportionately high costs and that management strategies focused on CKD alone may underestimate total care burden. The lifetime cost of a patient with IgAN progressing to end-stage kidney disease can exceed $1 million to $2 million when dialysis, transplantation, and indirect costs are factored in.⁵

Why the Findings Matter for Managed Care

The study's authors are explicit about the managed care implications. With disease-specific therapies for IgAN, including the recently FDA-approved sibeprenlimab-szsi (Voyxact; Otsuka), which received accelerated approval in late 2025 for reducing proteinuria in adults at risk of disease progression,⁶ entering a treatment landscape long dominated by supportive care, the ability to stratify patients by anticipated health care burden is increasingly important for both clinical and reimbursement decision-making.

The study does carry methodological limitations. Its retrospective design and reliance on a single integrated health system mean that patients with mild IgAN who were never biopsied would not have been captured, and the insured, integrated-care population may not reflect outcomes among uninsured patients or those outside similar systems. Selection bias is a meaningful caveat.

Despite the limitations, the study’s findings indicate clinical characteristics at the time of biopsy can be predictive of future HCRU.

“The identification of patients who are more likely to require intensive management in the future can potentially inform the risk/benefit assessments of patients and providers in determining a course of treatment, as well as health-economic decision-making regarding reimbursement for treatment,” the authors concluded.

Two of the study's coauthors are employees of the manufacturer of sibeprenlimab, Otsuka Pharmaceutical Development and Commercialization, Inc, which also funded the research, and one is an employee of Visterra, Inc, a subsidiary of Otsuka.

References

1. Cannizzaro N, Gandhi HK, Chen Q, et al. Clinical characteristics as predictors of healthcare resource utilization in immunoglobulin A nephropathy: a retrospective database study. JHEOR. 2026;13(1):211-217. doi:10.36469/jheor.2026.158847
2. Hillenbrand A. IgA nephropathy in 2025: year in review. HCPLive^®. December 27, 2025. Accessed June 12, 2026. https://www.hcplive.com/view/iga-nephropathy-2025-year-review
3. Preventing progression in IgA nephropathy: a managed care focus on emerging therapies. Am J Manag Care. 2023;29(suppl 3):S31-S43. doi:10.37765/ajmc.2023.89344
4. Lerma EV, Bensink ME, Thakker KM, et al. Impact of proteinuria and kidney function decline on health care costs and resource utilization in adults with IgA nephropathy in the United States: a retrospective analysis. Kidney Med. 2023;5(9):100693. doi:10.1016/j.xkme.2023.100693
5. Key managed care considerations for IgA nephropathy treatment. AJMC^®. June 9, 2025. Accessed June 15, 2026. https://www.ajmc.com/view/key-managed-care-considerations-for-iga-nephropathy-treatment
6. Jeremias S, Kim JP. FDA approval of sibeprenlimab signals new era in IgA nephropathy: Jackson Peter Kim, MD. AJMC. February 16, 2026. Accessed June 15, 2026. https://www.ajmc.com/view/fda-approval-of-sibeprenlimab-signals-new-era-in-iga-nephropathy-jackson-peter-kim-md