Mathematical Model Aims to Improve Cost-Effectiveness of Rheumatology Treatment

Biological therapies for moderate to severe rheumatoid arthritis have significantly improved treatment and prognosis. However, the high cost of treatment may be a barrier to access. Researchers led by Devin Incerti, a health economist and data scientist at the Innovation and Value Initiative in Oakland, Calif., are developing a cost-effectiveness mathematical model to align prices with value. They shared their latest findings with attendees at the 2017 annual meeting of the American College of Rheumatology (ACR) and the Association of Rheumatology Health Professionals (ARHP).

In their abstract titled, “Open-Source Consensus-Based Models to Improve the Cost-Effectiveness of Rheumatology Care,” the authors said the literature lacks consensus on such models, and that estimates of treatment value vary widely. In addition, they said, because new evidence regarding biologics is being generated rapidly, any model that estimates value must continually evolve and update as well. They called for “transparent, flexible, and accessible cost-effectiveness models that shed light on the implications of different modeling approaches.”

The researchers developed an open-source set of cost-effectiveness models and made it publicly available on GitHub and as an R package. They also created a web application where users can run the model online, modifying their own parameter values and structural assumptions. They then applied a number of different plausible modeling assumptions to their model to compare the cost-effectiveness of a standard sequence of six biologic treatments to conventional disease-modifying antirheumatic drugs (cDMARDs).

They found that incremental cost-effectiveness ratios ranged from less than $100,000 to about $300,000. The modeling system predicted that biologics would be more cost-effective than conventional DMARDS when:

  • Biologics had a larger effect on the Health Assessment Questionnaire (HAQ) Disability Index score at six months.
  • Increases in HAQ score were assumed to lead to larger increases in mortality.
  • The drop in clinical efficacy after each treatment failure was smaller.
  • The HAQ score of patients receiving conventional DMARDs progressed more quickly over time.
  • Biologics were discounted more from their wholesale acquisition cost.
  • Productivity losses were larger.

Subgroup analyses also found that that biologics would be more cost-effectiveness in younger patients, with incremental cost-effectiveness ratios ranging from $100,00 at age 35 to $165,000 at age 70.

The authors called for additional cost-effectiveness studies and processes that will encourage collaboration, reduce diversity in modeling approaches, and apply new evidence in biologics.