Study details cost-effectiveness of rheumatoid arthritis treatments for Medicare recipients

Apr 15 2008

For elderly and disabled rheumatoid arthritis (RA) sufferers, the Medicare Prescription Drug Improvement and Modernization Act (MMA) brought the promise of better disease management with "biologic" drugs.

Prior to its passage in 2006, Medicare covered only one of the tumor necrosis factor á (TNFá) inhibitors, the infusion drug infliximab, also known by its brand name, Remicade. Since the MMA, most Medicare prescription drug plans offer coverage of the anti-TNFá self-injectables etanercept (Enbrel) and adalimumab (Humira), as well as the interleukin-1 receptor antagonist anakinra (Kineret). More effective at controlling the painful and crippling symptoms of RA than conventional disease-modifying antirheumatic drugs (DMARDs), biologic drugs are also more expensive. According to a recent study, this new class of therapies has increased the cost of treating a patient with RA in the United States 3-fold.

To help Medicare beneficiaries and their providers select the best-value treatment option, a team of researchers, supported by the Agency for Healthcare Research and Quality of the U.S. Department of Health and Human Services, developed a mathematical model to estimate the costs and benefits of etanercept, adalimumab, and anakinra compared with those of infliximab over a patient's lifetime. Their results, featured in the April 2008 issue of Arthritis & Rheumatism (www.interscience.wiley.com/journal/arthritis ), make a case for coverage of either etanercept or adalimumab over infliximab. In terms of effectiveness, the 3 TNFá inhibitors are nearly equal. Getting the same results with infliximab, however, requires paying more—roughly $13,000 more—per patient. Anakinra is substantially less costly than the anti-TNFá drugs but also less effective.

The researchers drew on data on RA patients from randomized controlled trials and a storehouse of self-reported patient information, the National Data Bank for Rheumatic Diseases. Starting with baseline characteristics—including disease duration and score on the disability index of the Health Assessment Questionnaire (HAQ DI)—of actual patients treated with each of the targeted biologic drugs, the model simulated a representative sample of 10,000 RA patients. Using these simulated patients, the model assessed the effectiveness of the 4 options, based on the level of American College of Rheumatology (ACR) response and the HAQ DI score for each patient. Beginning after a 6-month course of biology therapy, scores were taken every 6 months until withdrawal, due, for example, to loss of effectiveness or adverse event, and then, assuming a return to DMARD-based therapy, every 6 months throughout the remainder of the patient's life. The score for each patient was translated into quality-adjusted life years (QALYs), a measure of benefit that can be used across a wide range of diseases and treatments. The model then calculated the costs incurred for each Medicare patient, including the costs of the biologic drugs, physician visits, other medications, hospitalizations, radiographs, and laboratory work. Finally, the researchers compared the costs and QALYs generated by each of the 4 biologic agents.

In all simulations, anakinra was found to generate less QALYs than the TNFá inhibitors. Excluding anakinra to compare the costs of the 3 almost equally effective drug strategies, researchers used a range of $0 to $200,000 as the values a decision-maker may be willing to pay per additional QALY gained. Infliximab was the optimal strategy in only a handful of the simulations. If society were willing to pay as much as $50,000 per QALY, the probability that infliximab would be cost-effective is less than 1 percent.

“Our analysis suggests that the use of etanercept or adalimumab in place of infliximab as a first-line biologic agent is likely to be considered cost effective,” concludes the study's lead author, Dr. Allan J. Wailoo. Yet, as he acknowledges, this cost-effective analysis does have several limitations. For one, it does not consider whether any biologic agent is cost-effective compared with traditional DMARD therapy. For another, it focuses only on patients with established disease, averaging 7 or more years in duration. What's more, only very slight changes in the doses of etanercept and adalimumab were documented in the sample of RA patients on which the simulations were based. “Increases in doses will substantially influence the cost and cost-effectiveness of biologic drugs,” Dr. Wailoo notes, “and it is therefore recommended that this issue be monitored.”