DETERMINANTS OF COST-EFFECTIVENESS OF ADALIMUMAB FOR RHEUMATOID ARTHRITIS

Purpose:

Rheumatoid Arthritis (RA) can be treated with TNF-α inhibitors after the failure of conventional disease-modifying antirheumatic drugs like Methotrexate. Cost-effectiveness estimates vary widely around the world. In Germany, the clinical use of TNF-α inhibitors grew from 2 % of treated RA patients in 2000 to 20 % in 2008. In 2012, Adalimumab was the most popular TNF-α inhibitor and the best selling drug in the German statutory health insurance system with net expenditure of € 581 mn. We aim to analyze the determinants of cost-effectiveness of Adalimumab for the treatment of RA in Germany.

Method:

We set up an individual patient sampling lifetime model to simulate 10,000 hypothetical patients. Initially, patients can achieve one of three responses according to American College of Rheumatology criteria or fail the therapy. Each response is associated with an initial improvement in functional status. In each cycle, treatment might be discontinued due to loss of efficacy or adverse events. Extensive sensitivity analysis investigates the effects of baseline age and functional status, cost and health effects discounting, methods for estimating quality of life and time horizon.

Result:

In the base case, patients gain 7.07 quality-adjusted life years (QALYs) with conventional synthetic therapy and 9.92 QALYs if Adalimumab combination therapy is added to the treatment algorithm. The incremental cost-utility ratio (ICUR) is € 24,492 based on German list prices. After deduction of mandatory rebates and taxes, the ICUR is only € 17,277. Adalimumab combination therapy lowers indirect costs from € 162,698 to € 134,363. The ICUR based on total costs is € 14,550 (€ 7,335 after deducting taxes and rebates). Sensitivity analyses shows that Adalimumab combination therapy becomes a dominant treatment option for younger baseline populations, i.e. Adalimumab is both more effective and less expensive for baseline age 30 due to savings in indirect costs.

Conclusion:

Cost-effectiveness of Adalimumab combination therapy in Germany compares favorably to analyses in other countries. Our complex probabilistic model shows that incorporation of indirect costs and a sufficiently long simulation horizon are necessary to capture the complete range of possible outcomes and the associated longterm benefits of biological treatment. The most important determinant of cost-effectiveness is savings in indirect costs. Adalimumab combination therapy is most cost-effective for societies with high indirect costs.