Uptake and cost of biosimilar filgrastim among Medicare and Medicaid populations in 2015-2018

Filgrastim and infliximab biosimilar uptake in Medicare Advantage compared with Traditional Medicare, 2016-2019

BACKGROUND

Medicare Advantage (MA) and Traditional Medicare face different financing structures and incentives and may implement different strategies to encourage biosimilar uptake. Strategies used by health insurers can influence biosimilar uptake, which can in turn promote savings to insurers and patients.

OBJECTIVE

To compare filgrastim and infliximab biosimilar uptake between MA and Traditional Medicare from 2016 to 2019 and examine biosimilar uptake by different MA carriers and plan types (Health Maintenance Organization [HMO] or Preferred Provider Organization).

METHODS

We use a 2016-2019 nationally representative random 20% sample of the carrier (physician) and outpatient paid claims for Traditional Medicare data and final-action carrier and outpatient records for MA data. We compare quarterly biosimilar uptake from 2016 to 2019 for the first 2 drugs with biosimilar competition: (1) filgrastim, (Neupogen, originator), and biosimilars tbo-filgrastim (GRANIX) and filgrastim-sndz (ZARXIO), and (2) infliximab (Remicade, originator), and biosimilars infliximab-dyyb (Inflectra) and infliximab-abda (Renflexis).

RESULTS

From their introduction, there was consistently greater uptake of filgrastim and infliximab biosimilars in MA compared with Traditional Medicare. By Q4 2019, filgrastim biosimilar uptake was 7.6 percentage points higher in MA (80.3%) than Traditional Medicare (72.7%). By Q4 2019, infliximab biosimilar uptake was 28.7% and 15.4% in MA and Traditional Medicare, respectively. Kaiser HMO plans were primarily responsible for the higher uptake of biosimilars in MA; in Q4 2019, filgrastim and infliximab biosimilar uptake was 98.8% and 78.8%, respectively.

CONCLUSIONS

Our findings suggest that filgrastim and infliximab biosimilar uptake is greater in MA compared with Traditional Medicare, which is driven in part by particularly high uptake of biosimilars in MA Kaiser HMO plans. This highlights the need for future work to examine specific strategies and levers employed by MA Kaiser HMO plans and other insurers to increase biosimilar uptake, which can lead to cost savings for physician-administered drugs.

Utilization of Filgrastim and Infliximab Biosimilar Products in Medicare Part D, 2015-2019

This cross-sectional study examines utilization trends for filgrastim and infliximab products and their biosimilars to understand whether biosimilars are associated with reduced spending in Medicare Part D.

Trends in Use of Granulocyte Colony-Stimulating Factor Following Introduction of Biosimilars Among Adults With Cancer and Commercial or Medicare Insurance From 2014 to 2019

IMPORTANCE

The introduction of biosimilars and novel delivery devices between 2014 and 2019 may have changed the utilization of granulocyte colony-stimulating factors (G-CSF).

OBJECTIVE

To assess utilization trends of G-CSFs for primary prophylaxis of febrile neutropenia (FN) among patients with cancer receiving myelosuppressive chemotherapy with commercial or Medicare insurance.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study assessed G-CSF utilization trends overall and stratified by regimen febrile neutropenia risk level. Associations between patient characteristics and G-CSF use were evaluated. Patients with cancer, including breast, lung, colorectal, esophageal and gastric, pancreatic, prostate, ovarian, and non-Hodgkin lymphomas, initiating myelosuppressive chemotherapy courses were included from the 2014 to 2019 commercial insurance and 2014 to 2018 Medicare fee-for-service claims databases. Data were analyzed from March to June 2021.

EXPOSURES

Year of chemotherapy initiation.

MAIN OUTCOMES AND MEASURES

The main outcomes were use and trends of G-CSFs for primary prophylaxis, from completion to 3 days after in the first chemotherapy cycle.

RESULTS

In total, 86 731 chemotherapy courses (mean [SD] age, 57.7 [11.5] years; 57 838 [66.7%] women and 28 893 [33.3%] men) were identified from 82 410 patients in the commercial insurance database and 32 398 chemotherapy courses (mean [SD] age, 71.8 [8.3] years; 18 468 [57.0%] women and 13 930 [43.0%] men) were identified from 30 279 patients in the Medicare database. Among the commercially insured population, 39 639 patients (45.7%) received G-CSFs, and 12 562 patients (38.8%) received G-CSFs among Medicare insured patients. Overall G-CSF use increased significantly throughout the study period in both populations, from 45.1% (95% CI, 44.4%-45.7%) of patients in 2014 to 47.5% (95% CI, 46.5%-48.5%) of patients in 2019 (P = .001) in the commercially insured population and from 36.0% (95% CI, 34.2%-38.0%) of patients in 2014 to 39.1% (95% CI, 38.1%-40.1%) of patients in 2018 (P < .001) in the Medicare population. The greatest increases in G-CSF use were observed among patients with high FN risk, from 75.0% (95% CI, 74.1%-76.0%) of patients to 83.2% (95% CI, 82.0%-84.2%) of patients (P < .001) among the commercially insured population and 75.3% (95% CI, 71.8%-78.6%) of patients to 86.2% (95% CI, 84.7%-87.6%) of patients (P < .001) among the Medicare population. Use of G-CSFs decreased in the commercially insured population among patients with intermediate FN risk (from 27.5% [95% CI, 26.4%-28.5%] of patients to 20.4% [95% CI, 19.1%-21.7%] of patients; P < .001) or low FN risk (from 19.3% [95% CI, 18.3%-20.4%] of patients to 16.3% [95% CI, 14.7%-18.0%] of patients; P < .001) and remained stable in the Medicare population (intermediate risk: from 26.4% [95% CI, 23.8%-29.2%] of patients to 28.4% [95% CI, 27.0%-29.8%] of patients; P = .35; low risk: from 19.6% [95% CI, 17.0%-22.4%] of patients to 20.9% [95% CI, 19.6%-22.3%] of patients; P = .58). Factors associated with increased odds of G-CSF use included older age (commercial insurance: adjusted odds ratio [aOR], 1.50 [95% CI, 1.41-1.59]; Medicare: aOR, 1.36 [95% CI, 1.08-1.71]), receiving a regimen with high FN risk (commercial insurance: aOR, 16.01 [95% CI, 15.17-16.90]; Medicare: aOR, 17.17 [95% CI, 15.76-18.71]), and history of neutropenia (commercial insurance: 3.90 (3.67-4.15); Medicare: 3.82 (3.50-4.18).

CONCLUSIONS AND RELEVANCE

This cross-sectional study found that utilization of G-CSFs increased among patients with cancer with high FN risk in both a commercially and Medicare-insured population, but 14% to 17% of patients still did not receive preventive treatment.