OBJECTIVES

Typically, medication adherence calculations include discontinuation when evaluating treatment outcomes. However, most cost-effectiveness analyses of sequences of rheumatoid arthritis(RA) treatment assume that patients will progress through the full sequence (full-sequence model). We aimed to determine if discontinuation of biological treatment (drop-out model) affects the short-term cost-effectiveness of sequences of therapeutic drugs for RA patients after failure of initial tumor necrosis factor inhibitor(TNFi).

METHODS

From the 2008-2016 Truven Health MarketScan Research database, we derived a cohort of patients who failed their first TNFi. We calculated probabilities of switching, continuing or discontinuing therapy and per cycle (6-months) drug-related and other health-care costs. We used the Birmingham RA Model formula to convert Health Assessment Questionnaire-Disability Index values, derived from an age-adjusted comorbidity index, to utilities. We created a microsimulation model and ran 10,000 patients through sequences of three drugs to determine the incremental cost-effectiveness of beginning with adalimumab(cycling) versus abatacept(swapping).

RESULTS

The Truven cohort (n=10,442, 80% female, mean age 52yrs) were on adalimumab (n=2,732, 26.1%) and abatacept (2,073(19.9%) for a median of 418 and 582 days respectively.15.2% and 13.8% stopped biological treatment thereafter. Over two years, swapping had a higher discounted cost($66,260 vs. $65,596) and QALY(0.92 vs. 0.91) with an ICER of $74,185/QALY gained. These costs are lower than those of the full-sequence model ($74,460 and $73,838) for similar QALY benefit (ICER: $96,030/QALY). Similarly, over 5 years the swapping ICER was $99,831/QALY in the drop-out model versus $150,872/QALY in the full-sequence model.

CONCLUSIONS

To our knowledge, this is the first time patients dropping out of sequence of treatment have been modeled. While this did not affect the direction of results, there was a large impact on the ICER which has repercussions for decision makers and coverage policy. Economic evaluation guidelines should be updated to recommend including discontinuation rates for more accurate ICERs.