To estimate the incremental cost per quality-adjusted life-years (QALYs) for abatacept and rituximab, in combination with methotrexate, relative to methotrexate alone in patients with active rheumatoid arthritis (RA).
A patient-level simulation model was used to depict the progression of functional disability over the lifetimes of women aged 55-64 years with active RA and inadequate response to a tumor necrosis factor (TNF)-alpha antagonist therapy. Future health-state utilities and medical care costs were based on projected values of the Health Assessment Questionnaire Disability Index (HAQ-DI). Patients were assumed to receive abatacept or rituximab in combination with methotrexate until death or therapy discontinuation due to lack of efficacy or adverse events. HAQ-DI improvement at month 6, after adjustments for control drug (methotrexate) response, was derived from two clinical trials. Costs of medical care and biologic drugs, discounted at 3% annually, were from the perspective of a US third-party payer and expressed in 2007 US dollars.
Relative to methotrexate alone, abatacept/methotrexate and rituximab/methotrexate therapies were estimated to yield an average of 1.25 and 1.10 additional QALYs per patient, at mean incremental costs of $58,989 and $60,380, respectively. The incremental cost-utility ratio relative to methotrexate was $47,191 (95% CI $44,810-49,920) per QALY gained for abatacept/methotrexate and $54,891 (95% CI $52,274-58,073) per QALY gained for rituximab/methotrexate. At an acceptability threshold of $50,000 per QALY, the probability of cost effectiveness was 90% for abatacept and 0.0% for rituximab.
Abatacept was estimated to be more cost effective than rituximab for use in RA from a US third-party payer perspective. However, head-to-head clinical trials and long-term observational data are needed to confirm these findings.