A COST-EFFICACY COMPARISON OF ADALIMUMAB AND ETANERCEPT IN THE TREATMENT OF RHEUMATOID ARTHRITIS

Background: Etanercept and adalimumab are indicated in the treatment of rheumatoid arthritis (RA). Both have demonstrated improved effectiveness in reducing symptoms, retarding joint destruction, and improving physical function and health-related quality of life. Each has different attributes regarding safety, tolerability, effectiveness, and cost. Cost-efficacy analyses can be used to compare the value of similar treatments.Objectives: The purpose of this study was to compare the cost-efficacy of adalimumab and etanercept in the treatment of RA, using the American College of Rheumatology (ACR) response criteria as the efficacy endpoint.Methods: A cost-efficacy analysis was conducted comparing adalimumab and etanercept. The perspective was that of a United States (US) managed care organization. The time horizon was one year. Inputs to the model were chosen from comparable clinical trials. Efficacy endpoints were ACR20 and ACR50, available from trial reports and the package inserts at six months and assumed to remain constant at one year. Treatment scenarios were the regimens from package inserts. For adalimumab, the dosage regimens were 40mg every other week (qow), 40mg every week (qw), and 40mg qow with methotrexate (MTX) 15mg qw. For etanercept, the dosage regimens were 25mg twice weekly (biw) and 25mg biw with MTX 15mg qw. Adverse events as reported in the package inserts and the costs to treat them were also incorporated into the model. The rate of serious adverse events was assumed to be 5% for each drug; the rate of minor adverse events was assumed to be the same as upper respiratory infections (29% for etanercept and 17% for adalimumab). Medication costs were based upon US average wholesale price. Other costs were those published by Medicare and in the Medstat DRG Guide. Sensitivity analyses were conducted on drug costs, adverse event rates, and efficacy measures to test for robustness of the results.Results: Results are presented in US$. Etanercept (E) and adalimumab (A) in the selected treatment and dosage scenarios are compared in the table, based on the annual cost of therapy, the ACR20 or ACR50 response rates, and the annual cost per responder. Cost Efficacy Results Based on ACR20 and ACR50 Response Rates Treatment scenario Annual Cost ACR20 Cost Per ACR50 Cost Per of Response ACR20 Response ACR50 Therapy Rate Responder Rate Responder E 25mg biw 17413 0.59 29369 0.40 43319 A 40mg qow 17400 0.46 40672 0.22 78643 A 40mg qw 34644 0.53 65218 0.35 98758 E 25mg biw + MTX 18578 0.71 26167 0.39 47636 A 25mg qow + MTX 18566 0.63 29468 0.39 47605 ]Conclusion: This analysis suggests that, overall, the most cost-efficacious therapy for treatment of rheumatoid arthritis is etanercept.Citation: , volume , supplement , year 2003, page Session: Health services, economics and outcome research