gms | German Medical Science

Background: Anti-citrullinated protein antibody (ACPA)-positive (+) patients tend to develop more severe, erosive disease than ACPA-negative patients [1]. In an observational study using data from the largest real-world rheumatology registry (~43,000 patients) that explored ACPA status on RA treatment response to abatacept or a TNF inhibitor (TNFi), for a typical ACPA+ patient, mean (SE) changes from baseline in CDAI at 6 months were –8.8 for abatacept and –5.6 for a TNFi [2]. This study evaluated the costs and cost-effectiveness of treating ACPA+ patients with RA with abatacept versus a TNFi on background MTX.

Methods: An economic analysis was carried out investigating lifetime direct costs and quality-adjusted life years (QALYs) of ACPA+ patients with RA treated with abatacept or a TNFi in Germany. QALYs are a measure of disease burden, adjusted to reflect quality of life. As clinical outcomes data were from the registry study, a typical patient, whose baseline characteristics (female, age=57, BMI=30 kg/m², CDAI=20, 1 prior biologic) were based on the observational study, was modelled. CDAI changes at 6 months for each treatment were converted to HAQ changes, and disease progression was based on HAQ score changes over time. Discontinuation of therapy at 6 months was based on rates from the registry study. Mean time on treatment was derived from the literature [3]. In the base case, patients discontinuing abatacept or TNFi moved to standard care. Total non-drug direct medical costs and quality of life scores, correlated to HAQ scores, were calculated. Direct costs included hospitalizations and treatment costs. Differences in calculated costs and QALYs between abatacept and TNFi initiators were used to obtain the incremental cost-effectiveness ratio (cost per QALY gained). Annual costs of TNFi were calculated as a weighted average based on the distribution and costs of TNFi drugs in Germany (19,762€).

Results: Total lifetime costs for TNFi initiators were higher than for abatacept (85,278€ and 82,288€, respectively). Abatacept treatment also resulted in lower hospitalization costs. Based on a typical patient from the observational study, the total estimated QALYs for abatacept and TNFi initiators were 6.72 and 6.58, respectively. From a cost-effectiveness perspective, abatacept was the dominant strategy versus TNFi (less costly and more effective). In a sensitivity analysis assuming 100% biosimilar use for etanercept and infliximab, an incremental cost-effectiveness of 3004€/QALY was obtained.

Conclusion: Based on real-world data, abatacept is a cost-effective alternative to TNFi in ACPA+ patients with RA within the German healthcare system.