Modelling the cost effectiveness of TNF-alpha antagonists in the management of rheumatoid arthritis: results from the British Society for Rheumatology Biologics Registry

Abstract

Objective: To evaluate the cost effectiveness of TNF-alpha antagonist therapies for rheumatoid arthritis (RA) in the United Kingdom using data from the British Society for Rheumatology Biologics Registry (BSRBR).

Methods: A simulation model is constructed to quantify the cost effectiveness of the TNF-alpha antagonist therapies (infliximab, etanercept and adalimumab) as a group versus traditional disease-modifying anti-rheumatic drugs, with a time horizon over the full patient lifetime. Participants are UK NHS patients in the BSRBR with RA who have failed at least two traditional disease-modifying anti-rheumatic drugs. The BSRBR aims to recruit all RA patients starting on a TNF-alpha antagonist agent and follows them 6 monthly via consultant and patient administered questionnaires. Data collected include disease activity scores (DAS28), the Health Assessment Questionnaire and the SF-36. Costs include drug, monitoring and hospitalisations. Benefits are measured in disability and quality of life improvements. The main outcome measure is the incremental cost per quality adjusted life-year gained (discounted).

Results: The basecase cost per quality adjusted life-year gained by using TNF-alpha antagonist therapies is estimated at pound23 882, with probabilistic uncertainty analysis suggesting that the probability that treatments are below 30,000 pounds per QALY is around 84%. The results are most sensitive to assumptions concerning long-term disability progression, discount rates and the validity or otherwise of SF6D derived utility measures. Subgroup analysis, monotherapy versus combination with methotrexate, and a limited analysis of sequential therapy with two TNF-alpha antagonist agents, suggest cost-effectiveness ratios around 20,000 pounds to 30,000 pounds.

Conclusions: The BSRBR data provide valuable evidence for estimating cost-effectiveness. The analysis concludes that current policies and practice for the use of TNF-alpha antagonist therapies, after RA patients have failed at least two traditional disease-modifying anti-rheumatic drugs, appear cost-effective in the context of the NICE re-appraisal of 2006 for England and Wales, thus supporting their decision to continue their reimbursement. Decision-makers worldwide might adapt this analysis because differential costs, discount rates and other factors could affect results. There remains uncertainty, particularly on long-term disease progression. Further data collection using the BSRBR is recommended, together with a revision to this analysis when data become available.