OBJECTIVES : Medicare coverage rules regarding infusible biological disease modifying anti-rheumatic drugs (bDMARDs) under Part B (medical benefit) and self-injectable bDMARDs under Part D (drug benefit) have stimulated the use of these drugs (about 57% of bDMARD users). Our objective is to assess overall utilization and compare healthcare costs, per Medicare, associated with infusible vs. self-injectable bDMARDs, among rheumatoid arthritis (RA) Medicare beneficiaries.

METHODS : We analyzed the 5% Medicare Chronic Conditions Warehouse database (2006-2015) using a retrospective cohort study design. The study cohort consisted of continuously enrolled, fee-for-service beneficiaries with RA. Healthcare costs for both infusible and self-injectable bDMARDs were attributed to all RA-related drug and direct medical costs incurred during the treatment duration. We used t-test to compare the unadjusted costs attributed to infusible and self-injectable drugs. The incremental cost of infusible bDMARDs was derived in the multivariate analysis, using a generalized liner model. All costs were converted to 2015 US dollars, per Consumer Price Index.

RESULTS : Among 39,224 Medicare beneficiaries with RA who were treated with anti-rheumatic drugs between 2006 and 2015, 14.6% (N=5,727) used infusible and 11.5% (N=4,527) used self-injectable bDMARDs. The unadjusted mean total healthcare cost among infusible bDMARD users was $ 51,904 and was $ 79,031 among self-injectable bDMARD users. The adjusted mean total healthcare cost for beneficiaries using infusible bDMARDs was $ 7,116.5 and $ 7,742 per person for those using self-injectable bDMARDs (p<0.05); with an average duration of 26.2 months and 23.7 months respectively. The medical cost was 9.3% higher among infusible bDMARD users (p<0.05) while the drug cost was equivalent among the two classes.

CONCLUSIONS : Overall, bDMARDs accounted for about one third of RA treatment for Medicare beneficiaries with RA. Although the drug cost was equivalent, infusible bDMARDs were associated with significantly higher medical costs as compared to self-injectable treatments.