Nationwide Trends and Cost Implications of Switching Between Infliximab Products

ABSTRACT

Objectives: The introduction of infliximab biosimilars in the US has helped curb health care costs through competitive pricing. Many insurance payers have mandated switches from the originator to an infliximab biosimilar citing cost savings. This study assessed the cost savings to insurance payers and patients associated with switching infliximab products using a commercial claims database.

Study Design: This is a retrospective cohort study of commercially insured patients who received multiple infliximab products between 2015 and 2021 using administrative claims data.

Methods: Infliximab outpatient claims from 2015 to 2021 were reviewed using the Merative MarketScan Commercial Claims and Encounters Database. Patients who switched infliximab products were identified by changes in Current Procedural Terminology codes. Cost savings to insurance payers and patients were calculated with infliximab product switches.

Results: A total of 1785 patients underwent at least 1 infliximab product switch, with the majority occurring in 2021. Of the first-time switches, 92% (n = 1642) were from the infliximab originator to a biosimilar, with 72% (n = 1286) switching to infliximab-dyyb (Inflectra; Celltrion, Inc). Thirteen percent (n = 232) underwent 2 or more switches. Insurance payers saw a peak savings from product switching in 2019, with a median (IQR) of $1088 ($612-$1888) saved per infusion. Savings decreased to $61 (–$321 to $639) per infusion in 2021. Median patient out-of-pocket savings remained $0 throughout the study.

Conclusions: Switching to infliximab biosimilars increased over the study period. Cost savings for insurers peaked in 2019 but were negligible by 2021. Patients did not experience any savings from switching. Because nonmedical switching burdens providers and risks patient harm without clear economic benefits, mandatory switches demand greater system transparency to prioritize patient welfare.

Am J Manag Care. 2026;32(8):e294-e301.

doi:10.37765/ajmc.2026.89995

Takeaway Points

• Patients with commercial insurance from 2015 to 2021 did not experience any out-of-pocket savings from switching infliximab products.
• Insurance payers saw peak savings from infliximab product switching in 2019, with a median (IQR) of $1088 ($612-$1888) saved per infusion. Savings decreased to $61 (−$321 to $639) per infusion in 2021. If insurance payers are mandating infliximab product switches, it implies the existence of financial incentives not readily apparent in claims data. This highlights the need for greater transparency within the commercial health care system to ensure that patient welfare remains central to formulary and coverage decisions.
• Four percent of patients receiving an infliximab product in the Merative MarketScan Commercial Claims and Encounters Database from 2015 to 2021 received at least 2 different infliximab products, with more than half of all switches occurring in 2021.

Infliximab (Remicade; Janssen Biotech, Inc) is a monoclonal antibody that has become a cornerstone in the management of various inflammatory diseases such as rheumatoid arthritis and inflammatory bowel disease. It targets tumor necrosis factor-α to reduce inflammation and alleviate symptoms.¹ Approved by the FDA in 1998, infliximab is highly effective¹ but also very costly, thus prompting the ongoing development of biosimilars.^2,3 Infliximab biosimilars are highly similar to the originator infliximab biologic, offering comparable safety and efficacy at a lower cost.⁴ Initially, the cost of biosimilars was estimated to be 20% to 50% less than that of the originator biologic.^5,6 Real-world data have demonstrated that the introduction of the first infliximab biosimilar in 2016 and its increased usage led to a decrease in the price of both the originator and biosimilars over the first 5 years.^7,8 Our previous study using the Merative MarketScan Commercial Claims and Encounters Database found health care cost savings of at least $260 million to $842 million in the US over the first 5 years of infliximab biosimilar usage, with all infliximab products priced very similar to each other by 2021.⁷

With multiple infliximab biosimilars now available in the US, many insurance payers are mandating that patients switch between infliximab products to reduce costs. Multiple adult and pediatric studies have found that switching between infliximab products is safe and does not impact disease control.^9-12 However, the insurance and patient cost savings associated with switching between infliximab products have not yet been studied.

The objectives of this study were to evaluate predictors of switches and to assess cost savings associated with a product switch to both insurance payers and patients using a large commercial claims database.

METHODS

Database

Using the Merative MarketScan Commercial Claims and Encounters Database, we obtained infliximab outpatient claims from January 1, 2015, to December 31, 2021. The Merative MarketScan Research Databases collect data from more than 263 million unique patients in the US and contain deidentified, longitudinal, patient-level claims and specialty data from inpatient, outpatient, and prescription drug services.¹³

Study Design: Inclusion and Exclusion Criteria

This study was a retrospective secondary data analysis. Outpatient infliximab claims were identified in the MarketScan database using Current Procedural Terminology (CPT) codes (eAppendix Table 1 [eAppendix available at ajmc.com]) from January 1, 2015, to December 31, 2021, for any individual aged 0 to 64 years.¹⁴ The inclusion and exclusion criteria applied to the data set were the same as in our previous study using the same MarketScan database, which evaluated the impact of the introduction of infliximab biosimilars on the cost of all infliximab products.⁷ Patients were excluded if specific data were missing (the patient identification number or the patient’s health care plan). Additionally, patients were excluded if they had a capitated health plan. Claims were included if the cost and dosage were present. Any patient who had a switch between infliximab products with a simultaneous gap in therapy lasting longer than 16 weeks was excluded because this study aimed to evaluate cost savings from switching, not new starts or reinductions.

Patients were identified as having switched infliximab products if there were claims with at least 2 different infliximab CPT codes under a unique patient identification number. The first CPT code created for infliximab biosimilars, Q5102, was a generic CPT code used for any infliximab biosimilar until March 31, 2018, after which unique codes were assigned to each biosimilar.¹⁴ Claims for Q5102 from November 1, 2016, to June 30, 2017, were assumed to be for infliximab-dyyb (Inflectra; Celltrion, Inc). Claims from July 1, 2017, to March 31, 2018, were excluded because both infliximab-dyyb and infliximab-abda (Renflexis; Samsung Bioepis Co, Ltd) were available, making it impossible to determine which product the patient received during that interval.

Demographic Data Collected

Demographic data, including patient age, geographic region, and International Classification of Diseases, Ninth Revision (ICD-9) and International Statistical Classification of Diseases, Tenth Revision (ICD-10) codes were recorded for each patient’s first infliximab claim. ICD-9 and ICD-10 codes for FDA-approved infliximab indications (Crohn disease, ulcerative colitis, rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis, and plaque psoriasis [eAppendix Table 2]) were captured from the first infusion. Patients treated for non–FDA-approved indications were recorded as “other.” For patients receiving the medication for multiple FDA-approved indications, each indication was recorded separately.

Cost Differences With Switching

The primary outcome of interest was evaluating the cost savings to insurance payers and patients associated with switching from one infliximab product to another. Cost savings were calculated as:

Cost savings = Cost of final infusion of infliximab product 1
– Cost of first infusion of infliximab product 2

The cost savings to insurance payers and patient out-of-pocket (OOP) costs were analyzed by savings per infusion and savings per vial. MarketScan reports the cost data for outpatient claims as “total cost,” which is the sum of the cost to insurance, a patient’s OOP cost, and coordination of benefits. OOP costs for patients are defined as the co-payment, coinsurance, and deductible added together. Cost to insurance is what the insurance payer was billed for the infliximab product, not necessarily what was actually paid.

Secondary outcomes included time spent on each infliximab product, identifying trends of infliximab product switching and evaluating the number of infliximab product switches per patient. Time spent from initiation of the second product was calculated until the end of the study period, discontinuation, a subsequent switch, or a change in insurance coverage.

Predictors for Switching Infliximab Products

We evaluated whether patient factors (adult vs pediatric, sex, age, geographic region in the US, indication, and health care plan type) predicted switching between infliximab products by comparing patients who switched with those who did not. Patients who did not switch were identified from our previous study, which used MarketScan data to evaluate costs for all infliximab products, regardless of whether a switch occurred.⁷

Statistical Analyses

We summarized continuous variables as median (IQR) and categorical variables as frequencies (%). Differences in pre- to postswitch doses were tested using a signed rank test. Univariable logistic regression models were fit to assess the association of demographic and clinical characteristics with having a switch. Additionally, a multivariable model predicting the odds of a switch was fit using a backward selection approach. Initially, variables that were significant in the univariable models were included in the multivariable model. Variables were removed if they were not significant in the multivariable model and were determined not to be confounders of the relationship between the other variables in the model and the outcome. A change of any OR by greater than 20% was used as a cutoff to determine whether a variable was a confounder. All statistical analyses were conducted using SAS 9.4 (SAS Institute Inc).

All cost data were adjusted for inflation using the Consumer Price Index for medical care to reflect prices in December 2021 US$.¹⁵

RESULTS

Baseline Data and Demographics

From 2015 to 2021, 2175 unique patients were identified with multiple CPT codes for infliximab products in the MarketScan database (eAppendix Table 1). A total of 328 (15%) patients were excluded because they had a gap in infliximab therapy of more than 16 weeks between product switches. After applying all exclusion criteria, 1785 patients met inclusion criteria. Their median (IQR) age was 40 (26-52) years, and 52% were female (Table 1). Eleven percent of switches (n = 191) occurred in pediatric patients (< 18 years). The median (IQR) preswitch dosages for adult patients (500 [400-600] mg) and pediatric patients (400 [300-500] mg) were similar. There was a significant difference in median (IQR) dosage before (500 [400-700] mg) and after (500 [400-700] mg) switching (P < .0001), but that difference was not clinically meaningful. The highest number of patients had Crohn disease (47%; n = 838), followed by ulcerative colitis (24%; n = 420). Among those who switched, 61% had a preferred provider organization (PPO) for their insurance plan type (Table 1).

Switching Infliximab Products

The majority of infliximab switches occurred in 2021, with 944 patients (53%) making a switch, followed by 2019 with 416 patients (23%) (Table 1). Prior to switching, patients remained on their initial infliximab product for a median (IQR) duration of 18 (9-36) months, during which they had a median (IQR) of 11 (5-19) infusion claims. However, this duration may be underestimated because data collection began in 2015 and some patients may have initiated treatment even earlier. Following the switch, patients received the second infliximab product for a median (IQR) of 5 (3-17) months, with a median (IQR) of 3 (2-7) claims.

Eighty-seven percent (n = 1553) experienced a single infliximab product switch, whereas 13% (n = 232) underwent 2 or more switches. Of those who switched at least once, 92% (n = 1642) initially received the originator infliximab product (Table 2). The most common subsequent products that patients were switched to included infliximab-dyyb (72%; n = 1286) and infliximab-abda (12.7%; n = 227) (Table 2).

Of the 232 patients who had 2 or more switches, 78% (n = 181) switched back to the infliximab originator with the second switch (eAppendix Table 3). Of the 232 patients who underwent multiple infliximab product switches, 62% (n = 144) of these 232 patients had previously switched to infliximab-dyyb. Of the 1642 patients who began treatment with the originator and switched to a biosimilar, 181 (11%) switched back to infliximab originator with their second switch (eAppendix Table 4).

Insurance and Patients Cost Savings With Infliximab Switches

Insurance payers experienced the greatest cost savings from infliximab switching in 2019, with a median (IQR) savings of $1088 ($612-$1888) per infusion (Figure 1 [A]) and $189 ($179-$241) per vial (Figure 1 [B]). Although the highest proportion of switches (53%) occurred in 2021, the median (IQR) cost savings that year dropped significantly to $61 (–$321 to $639) per infusion (Figure 1 [A]) and to $13 (–$57 to $125) per vial (Figure 1 [B]).

Figure 2 highlights the cost impact of switching between infliximab formulations. From 2018 to 2020, switching from the originator to any infliximab biosimilar consistently yielded substantial savings per infusion and per vial, regardless of the biosimilar selected (Figure 2 [A]). However, in 2021, these savings diminished considerably. In fact, switching from the originator to infliximab-axxq (Avsola; Amgen, Inc) resulted in a median (IQR) cost increase of $388 (–$581 to –$243) per infusion and an increase of $81 (–$81 to –$72) per vial (Figure 2 [A]). Switches between biosimilars or from infliximab-dyyb to the originator generally resulted in negligible cost savings per infusion and per vial (Figure 2 [B]). Notably, throughout the study period, patients did not experience any OOP savings when switching infliximab products, with a median OOP savings of $0 per infusion and per vial.

Predictors for Switching Infliximab Products

From 2015 to 2021, 39,986 patients in the MarketScan database received only 1 infliximab product and did not undergo a product switch (Table 3). Overall, approximately 4% of patients in the database experienced at least 1 infliximab product switch.

Factors associated with significantly greater odds of having at least 1 switch in univariable models included male sex; residing in the Midwest, the South, or an “unknown” region compared with the West; having Crohn disease; and having a consumer-directed health plan, high-deductible health plan, other plan, or PPO plan compared with a point-of-service plan (Table 3). Factors associated with significantly lower odds of at least 1 switch in univariable models included rheumatoid arthritis and psoriasis diagnoses. The factors that remained significant in a multivariable model were sex, region, rheumatoid arthritis, psoriasis, and plan type.

DISCUSSION

Biosimilars were introduced into the market to reduce health care costs by offering lower-priced alternatives to the originator biologic and fostering competition.^5,6 Initially, infliximab biosimilars were less expensive than the infliximab originator.⁷ However, as biosimilar utilization increased by 2019, the infliximab originator responded by also reducing its price.⁷ In December 2017, the price per vial of the infliximab originator was $1091; by December 2021, it had decreased by 62.0% to $415.⁷ Infliximab is dosed by weight, so the pediatric population most likely drove down median cost savings per infusion, accounting for 11% of the switchers, but it did not affect cost savings per vial. Between 2019 and 2021, the cost of both the infliximab originator and biosimilars continued to decline, resulting in minimal pricing differences between them by 2021.^7,8,16

The introduction of biosimilars increased competition, driving down the prices of both the originator and the 3 biosimilars on the market, achieving the goal to generate cost savings. In addition, the potential for patients established on the originator to switch to a biosimilar further pressured pharmaceutical companies to price their products competitively, thereby discouraging switching and providing additional cost savings. As a result, the cost savings from biosimilars stem more from the availability of multiple infliximab products than from switching from one product to another.

Despite this narrowing price gap, insurance payers have increasingly mandated that patients switch infliximab products, typically from the originator to a biosimilar, as a cost-containment strategy. This study established strict exclusion criteria, excluding 15% of patients who had a switch between infliximab products with a therapy gap exceeding 16 weeks. This is a limitation that could affect switching cost savings. During this study period (2015-2021), 4% of patients receiving infliximab in the MarketScan database underwent a product switch, with more than half occurring in 2021. Patients with Crohn disease were more likely to undergo a product switch, and patients with rheumatoid arthritis and psoriasis were less likely. This is most likely due to specific insurance policies. It is unknown why these policies might differ across autoimmune disorders. There were also regional differences, with patients living in the West region less likely to undergo a switch. This could be due to insurance plans in different states/regions having different policies that could affect drug coverage.

Numerous adult and pediatric studies have demonstrated that switching between infliximab products is both safe and effective,^9-12 but does switching infliximab products lead to meaningful health care savings for insurance payers, patients, or both?

In this study, patient OOP costs remained at a median of $0 throughout all infliximab product switches, indicating no direct financial benefit to patients. Insurance payers, on the other hand, experienced peak savings in 2019, with a median of $1088 saved per infusion and $189 per vial. However, by 2021, these savings had diminished significantly, becoming negligible in most cases.

In some instances, switching proved more costly for payers. For example, switching from infliximab-abda to the originator in 2018 or from infliximab-axxq to infliximab-dyyb in 2021 resulted in increased costs rather than cost savings.

The minimal ongoing savings to both insurance payers and patients raise questions about the rationale for switching patients between infliximab products. A change in infliximab products necessitates extensive communication from providers and nursing staff, who must educate patients and families about biosimilars, address concerns regarding safety and efficacy, and manage expectations around the switch. Given the lack of overall cost savings, it seems that mandated product switching by payers may impose a disproportionate burden on both patients and the health care system.

The responsibility for patient education and reassurance falls heavily on health care providers. This dynamic not only strains clinical resources but also increases the risk of the nocebo effect, where patients may experience adverse outcomes driven by negative expectations rather than pharmacologic differences.^17-19 Additionally, the administrative workload associated with switching, such as processing prior authorizations and updating treatment orders, further exacerbates provider burnout and diverts time from direct patient care.

Limitations

A key limitation in this study and the broader health care system is the lack of visibility into confidential agreements between insurers, pharmacy benefit managers (PBMs), and pharmaceutical manufacturers. The prices billed by pharmaceutical companies and the amounts paid by insurers are usually much lower for biologic medications due to PBM-negotiated rebates and discounts. These behind-the-scenes contracts may involve rebates or other financial arrangements that are not publicly reported, making it difficult to assess the true economic impact. This gap—the difference between list prices and net prices—has widened over time, especially for biologics facing biosimilar competition.^20,21 Nevertheless, if insurers are mandating product switches, it is reasonable to presume they perceive some form of benefit.

Second, this study is limited by the analysis of commercial insurance claims, which may limit the generalizability of the findings to patients with public insurance. Third, continuous insurance enrollment was not required for inclusion, which may introduce variability in the completeness of claims data. Fourth, interpreting OOP costs has its challenges due to the complexity of the US insurance system, including family members’ expenses and unrelated claims that can affect OOP costs. Fifth, MarketScan claims data do not capture patient savings from manufacturer-sponsored co-pay assistance or other financial support programs, which may lead to underestimation of actual patient savings. Despite these limitations, our findings are consistent with those of Feng et al, who analyzed MarketScan data from 2015 to 2018 and reported similar OOP costs among patients receiving infliximab originator and biosimilar products.¹⁶

Implications and Next Steps

Infliximab and other biologics have transformed the quality of life for patients with autoimmune conditions,^22-24 but affordability continues to be a significant problem.²⁵ Although biosimilars have increased infliximab utilization,⁸ access remains a barrier if patients still cannot afford their medication. Regulatory efforts are needed to advocate for patient savings and more transparency with insurance payers and PBMs. Our study found that patients have not seen any of these savings with infliximab biosimilars^7,16—yet are being required to switch infliximab products—and that insurance payers have not seen savings since 2019.

CONCLUSIONS

Infliximab biosimilars initially contributed to health care system savings by fostering market competition, which led to substantial price reductions for both the originator and biosimilar products. Initially, infliximab product switching contributed to health care cost savings for insurers, but by 2021, insurance payers saw minimal savings from switching patients between infliximab products. In the absence of meaningful cost reductions for either the health care system or patients, the practice of nonmedical switching imposes unnecessary administrative burdens on health care providers and may increase the risk of patient harm, particularly through the nocebo effect. If insurance payers continue to mandate such switches, these findings highlight the need for greater transparency within the commercial health care system, especially among insurers and PBMs, to ensure that patient welfare remains central to formulary and coverage decisions.

Author Affiliations: Department of Pediatric Gastroenterology, St Christopher’s Hospital for Children (SRP), Philadelphia, PA; Center for Biostatistics, Department of Biomedical Informatics, College of Medicine, The Ohio State University (MA-R), Columbus, OH; Biostatistics Resource (MA-R), Department of Pharmacy (MM), and Division of Gastroenterology, Hepatology, and Nutrition (RMM), Nationwide Children’s Hospital, Columbus, OH; Department of Pediatrics, The Ohio State University Abigail Wexner Research Institute at Nationwide Children’s Hospital (RMM), Columbus, OH.

Source of Funding: Nationwide Children’s Foundation.

Author Disclosures: Dr Maltz has received a Pfizer Inc biosimilar education grant and honoraria from Advent Health and the Crohn’s and Colitis Foundation. The remaining authors report no relationship or financial interest with any entity that would pose a conflict of interest with the subject matter of this article.

Authorship Information: Concept and design (SRP, MA-R, MM, RMM); acquisition of data (MA-R, RMM); analysis and interpretation of data (SRP, MA-R, MM, RMM); drafting of the manuscript (SRP, MA-R, MM, RMM); critical revision of the manuscript for important intellectual content (SRP, MA-R, MM, RMM); statistical analysis (MA-R, RMM); provision of patients or study materials (SRP); obtaining funding (SRP, RMM); and supervision (SRP, RMM).

Address Correspondence to: Samantha R. Paglinco, DO, St Christopher’s Hospital for Children, 160 E Erie Ave, Philadelphia, PA 19134. Email: samantha.paglinco@towerhealth.org.

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