OBJECTIVES: Healthcare costs associated with the intravenous infusion (IV) vs subcutaneous injection (SC) of belimumab for systemic lupus erythematosus (SLE) and tocilizumab for rheumatoid arthritis (RA) were examined respectively.

METHODS: Medicare patients were identified up to 3 years after FDA approval dates of the IV and SC drug formulations from Medicare fee-for-service data. Mean inpatient, outpatient, and drug costs were descriptively compared to understand if the drug delivery system influenced costs. Costs were adjusted to 2024 dollars.

RESULTS: IV belimumab was examined between 2012-2014 (n=457,605, 615); SC belimumab was examined between 2018-2020 (n=255, 396, 546). IV tocilizumab was examined between 2011-2013 (n= 1484, 2294, 3013); SC tocilizumab was examined between 2013-2015 (n=367, 357, 307). Mean age was 70-71 years for both belimumab cohorts; over 88% female; was 73-74 years for both tocilizumab cohorts and over 80% female. For the IV belimumab cohort, inpatient costs were $31,918, $26,129, and $24,924 and decreased by 31% in the first year (2108) that SC belimumab was introduced. Subsequent years saw increases of 8% and 38%. Outpatient costs were $13,161, $12,784, and $11,374 during the IV belimumab period and saw consistent decreases ranging from 27-35%. Drug costs saw consistent increases moving from an IV to SC formulation of 23%, 28%, 35% annually.

For the IV tocilizumab cohort, inpatient costs were $21,561, $26,350, and $26,346 and increased by 2% the first year SC tocilizumab was introduced. Subsequent years saw increases of 3% and 13%. Outpatient costs were $11,327, $11,297, and $10,566 during the IV tocilizumab period and saw decreases ranging from 5-13%. Drug costs saw consistent increases moving from IV to a SC formulation from 41%, 36%, 32% annually.

CONCLUSIONS: While inpatient costs fluctuated, outpatient costs consistently decreased and therapy costs consistently increased for belimumab and tocilizumab transitioning from IV to SC in Medicare FFS.