Background

Intravenous Immunoglobulin (IVIG) is an infusion therapy primarily used in the management of immunodeficiency disorders. The products are derived from pooled human plasma and contain immunoglobulins that serve as antibodies to help the immune system combat infections. IVIG is used across multiple medical specialties, such as allergy/immunology, neurology, and gastroenterology, and has demonstrated effectiveness in the treatment of a broad set of indications, including conditions like primary immunodeficiency, myasthenia gravis, and dermatomyositis. Multiple IVIG products are available on the market, with slight variations in their formulations; however, they are commonly used interchangeably across specialties and disease states.

Medicare coverage for IVIG is dependent on several factors, including patient indication and location of treatment, which determine whether the treatment is reimbursed under Medicare Parts B or D. The 21^st Century Cures Act established a home infusion benefit under Medicare Part B that covers IVIG therapy for the treatment of primary immunodeficiency disease (PIDD) as well as select diseases impacting the body’s immune system, effective January 1, 2021. Medicare Part D covers IVIG treatment in cases where the diagnosis or setting is not eligible for Part B coverage, such as indications outside of PIDD in which IVIG is an effective treatment option.

The IVIG market has grown substantially in the United States and is expected to continue growing as new indications are approved for treatment and awareness for the applications of IVIG grows. While demand is likely to continue to increase for these products, IVIG remains a high-cost treatment for payers, and this analysis seeks to better understand pricing and spending dynamics in Medicare as well as shifts in coverage for the drug class.

Analysis

To understand the pricing and spending dynamics for IVIG in Medicare Part D, Avalere Health completed an analysis of Medicare Part D drug event data and pricing data from 2017 through 2022, focusing on five commonly dispensed IVIG products within the scope of our study. These five products feature prominently in the IVIG products administered to Medicare beneficiaries in the home setting of care. To understand trends in Part D payments, we analyzed changes in price on a drug-by-drug basis using the per unit average allowed amount for each drug as well as changes in the aggregate Medicare payments across these products from 2017 through 2022.

We also examined the year-over-year changes in Part D IVIG unit volume for these products. In this portion of the analysis, we examined the trends in drug units dispensed under Part D, cross-referencing key policy changes to understand why certain year-over-year changes may have taken place.

Results

Growth in IVIG Price and Spend in Medicare Part D: Table 1 shows the average allowed reimbursement per unit for each IVIG product in the analysis, weighted by unit volume of select National Drug Codes (NDC), which are unique identifiers assigned to each drug product that captures information including the manufacturer, strength, and dosage form (e.g. liquid solutions, powders). The resulting compounded annual growth rate (CAGR) for allowed reimbursement per unit for these products was 8% over the five-year span.

Table 1. Medicare Part D IVIG Average Allowed Amount by Drug, Per Unit, 2017-2022

Figure 1 shows the total annual Part D payments for the five IVIG products within the scope of the study from 2017 through 2022. Total Medicare Part D payments across the five products increased from $656 million in 2017 to $1.5 billion in 2022, an average annual growth of 18%.

Figure 1. Total Medicare Part D Payments, for five IVIG products, 2017-2022 (in millions)

 IVIG Units Dispensed Under Medicare Part D: Figure 2 presents the number of IVIG units dispensed under Medicare Part D from 2017 through 2022 for each IVIG product included in the analysis. All products demonstrated positive growth rates over this period. Year-over-year growth across all 5 products accelerated from 2017 through 2020, then slowed in 2021 and 2022. The average annual growth was 10% between 2017 and 2022.

Table 2. Medicare Part D IVIG Units by Drug, 2017-2022 (in millions)

Discussion

Part D utilization and payments for the five IVIG products included in this analysis increased from 2017 through 2022 despite coverage available under Part B beginning in 2025. Allowed reimbursement saw average annual growth of 8%, and units dispensed increased by 10% annually, resulting in 18% growth per year in Medicare Part D payments. This shows that both price growth and utilization were drivers of increased spending on IVIG products over this time period.

The deceleration in year-over-year growth in the number IVIG units dispensed under Part D in 2020 and 2021 may be attributable to a shift in market share toward other IVIG products not captured in this analysis, as well as increased uptake of coverage under the Medicare Part B Home Infusion Benefit established in 2021 under the 21^st Century Cures Act. This analysis is not inclusive of all IVIG products on the market, so potential shifts in product preference or broader market dynamics are not fully reflected here and may contribute to the observed unit erosion. These results suggest that the introduction of the Part B Home Infusion Benefit may have resulted in a redistribution of IVIG unit volume across the Part D and Part B benefits.

Looking Ahead

Further exploration is needed to fully understand the dynamics of IVIG spending in Medicare Part D as well as the broader impacts of the introduction of the home infusion benefit on coverage category. Insights from this analysis can help to inform stakeholders of the trends in Part D spending for this subset of IVIG products and offer potential explanations for shifts in spending across Medicare benefits.

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