Background/Purpose: Rheumatoid arthritis (RA), a chronic inflammatory disorder, causes a significant decrease in quality of life. Recently developed biologic agents (BAs) have caused a considerable economic burden to society. Several previous studies have investigated the cost-effectiveness of specific BAs; however, they have not adequately considered BA utilization under real-life conditions. In actual clinical conditions, various individual patient-based factors influence BA utilization and timing of selecting, switching, or discontinuing agents. Previous studies on specific BAs considering only a few aspects of the conditions of RA patients in actual clinical practice were frequently based on controlled trials. In this study, we investigated the cost-effectiveness of selecting BAs followed by switching to other BAs or methotrexate (MTX) under actual clinical conditions using RA cohort database, the Institute of Rheumatology, Rheumatoid Arthritis (IORRA).

Methods: A Markov model-based probabilistic simulation from a societal perspective was conducted using a hypothetical population of 10,000 patients. Patients who had failed more than one disease-modifying antirheumatic drug (DMARD) and for whom BAs were selected started one of the four BAs (adalimumab, etanercept, infliximab, and tocilizumab) used in Japan in 2010, switched to other BAs or MTX, or discontinued all drugs comprised the BA group. Patients similar in background to the BA group who started MTX following discontinuation of all drugs comprised the comparator group (MTX group). Almost all model parameters were determined with respect to each group, except those related to effects and costs of the four BAs and MTX, based on clinical data extracted by the matching method from the IORRA. Health states in the model were defined on the basis of physical dysfunction levels stratified according to the Japanese version of the Health Assessment Questionnaire (J-HAQ), which corresponded to cost and utility. Lifetime costs, quality-adjusted life years (QALY), and incremental cost-effectiveness ratio (ICER) were calculated. The threshold ICER was assumed to be 5.0-6.0 million JPY (1 USD = 88 JPY in 2010). A lifetime horizon and a discount rate of 3% per year for both health benefits and costs were assumed. We also conducted a probabilistic sensitivity analysis.

Results: Clinical data from two groups of 454 patients each were used for calculating model parameters (percentages of patients in the BA group started adalimumab, etanercept, infliximab, and tocilizumab were 17.3%, 45.9%, 24.3%, and 12.5%, respectively). Lifetime costs in the BA and MTX groups were 34.8 and 24.1 million JPY and QALYs were 11.4 and 9.3, respectively. The average period with acceptable disability defined by J-HAQ <1.1 was longer in the BA group (15.8 years) than that in the MTX group (10.4 years). The ICER was 5.04 million JPY, with 75.8-89.1% probability of falling below 5.0-6.0 million JPY, respectively, according to probabilistic sensitivity analysis.

Conclusion: This study demonstrated that selecting BAs is cost-effective for RA patients who had failed more than one DMARD according to the analysis of data obtained from an observational cohort representing daily clinical practice in Japan.

ACR Meeting Abstracts - https://acrabstracts.org/abstract/evaluation-of-the-cost-effectiveness-of-rheumatoid-arthritis-treatment-with-biologic-agents-using-the-iorra-cohort-database/