LAUSR

Abstract Aims: To estimate real world healthcare costs and resource utilization of rheumatoid arthritis (RA) patients associated with targeted disease modifying anti-rheumatic drugs (tDMARD) switching in general and switching to abatacept specifically. Materials and methods: RA patients initiating a tDMARD were identified in IMS PharMetrics Plus health insurance claims data (2010–2016), and outcomes measured included monthly healthcare costs per patient (all-cause, RA-related) and resource utilization (inpatient stays, outpatient visits, emergency department [ED] visits). Generalized linear models were used to assess (i) average monthly costs per patient associated with tDMARD switching, and (ii) among switchers only, costs of switching to abatacept vs tumor necrosis factor inhibitors (TNFi) or other non-TNFi. Negative binomial regressions were used to determine incident rate ratios of resource utilization associated with switching to abatacept. Results: Among 11,856 RA patients who initiated a tDMARD, 2,708 switched tDMARDs once and 814 switched twice (to a third tDMARD). Adjusted average monthly costs were higher among patients who switched to a second tDMARD vs non-switchers (all-cause: $4,785 vs $3,491, p < .001; RA-related: $3,364 vs $2,297, p < .001). Monthly RA-related costs were higher for patients switching to a third tDMARD compared to non-switchers remaining on their second tDMARD ($3,835 vs $3,383, p < .001). Switchers to abatacept had significantly lower RA-related monthly costs vs switchers to TNFi ($3,129 vs $3,436, p = .021), and numerically lower all-cause costs ($4,444 vs $4,741, p = 0.188). Switchers to TNFi relative to abatacept had more frequent inpatient stays after switch (incidence rate ratio (IRR) = 1.85, p = .031), and numerically higher ED visits (IRR = 1.32, p = .093). Outpatient visits were less frequent for TNFi switchers (IRR = 0.83, p < .001) compared to switchers to abatacept. Limitations and conclusions: Switching to another tDMARD was associated with higher healthcare costs. Switching to abatacept, however, was associated with lower RA-related costs, fewer inpatient stays, but more frequent outpatient visits compared to switching to a TNFi.