Cost-effectiveness of adding magnetic resonance imaging to rheumatoid arthritis management

Abstract

Background: Early, aggressive treatment of rheumatoid arthritis (RA) improves outcomes but confers increased risk. Risk stratification to target aggressive treatment of high-risk individuals with early RA is considered important to optimize outcomes while minimizing clinical and monetary costs. Some advocate the addition of magnetic resonance imaging (MRI) to standard RA risk stratification with clinical markers for patients early in the disease course. Our objective was to determine the incremental cost-effectiveness of adding MRI to standard risk stratification in early RA.

Methods: Using a decision analysis model of standard risk stratification with or without MRI, followed by escalated standard treatment protocols based on treatment response, we estimated 1-year and lifetime quality-adjusted life-years, RA-related costs, and incremental cost-effectiveness ratios (with MRI vs without MRI) for RA patients with fewer than 12 months of disease and no baseline radiographic erosions. Inputs were derived from the published literature. We assumed a societal perspective with 3.0% discounting.

Results: One-year and lifetime incremental cost-effectiveness ratios for adding MRI to standard testing were $204,103 and $167,783 per quality-adjusted life-year gained, respectively. In 1-way sensitivity analyses, model results were insensitive to plausible ranges for every variable except MRI specificity, which published data suggest is below the threshold for MRI cost-effectiveness. In probabilistic sensitivity analyses, most simulations produced lifetime incremental cost-effectiveness ratios in excess of $100,000 per quality-adjusted life-year gained, a commonly cited threshold.

Conclusion: Under plausible clinical conditions, adding MRI is not cost-effective compared with standard risk stratification in early-RA patients.

Figure 1

Model decision trees. Risk-stratification tree represents risk stratification (standard testing with and without magnetic resonance imaging [MRI]) and “treat all” arms. Positive test result leads to baseline combination therapy. Treatment tree represents treatment regimens including optimized methotrexate monotherapy, escalated as needed; combination therapy of 2 or more traditional disease-modifying drugs (eg, triple therapy with hydroxychloroquine sulfate, sulfasalazine, and methotrexate); and biologic therapy (with methotrexate). Lack of treatment response (see text) leads to treatment escalation (from tier 1 to 2 and tier 2 to 3). ACR50 indicates American College of Rheumatology criteria for a 50% improvement in disease activity; RA, rheumatoid arthritis.

Figure 2

Threshold analysis for variables to which model output was sensitive in 1-way sensitivity analysis. Each horizontal bar represents the complete range of values for the variables listed on the vertical axis. Shaded areas represent those values that produced favorable (ie, <$100 000 per quality-adjusted life-year gained) incremental cost-effectiveness ratios (in dollars per quality-adjusted life-year gained) for a given strategy. For example, when the probability of remission after 6 months of methotrexate therapy is greater than 23.0%, standard risk stratification only is favored over the other strategies. Arrows indicate base case assumptions. MRI indicates magnetic resonance imaging; RA, rheumatoid arthritis.

Figure 3

Graphic depiction of test performance assumptions under which magnetic resonance imaging (MRI) plus standard risk stratification is the favored strategy (gray volume). Axes display plausible ranges for MRI sensitivity (horizontal) and specificity (depth) and standard risk stratification sensitivity (vertical, top) and specificity (vertical, bottom). Gray volume represents assumptions under which MRI is favored (ie, yields incremental cost-effectiveness ratios <$100 000 per quality-adjusted life-years gained [in dollars per quality-adjusted life-years gained]); the remaining space reflects assumptions under which standard risk stratification only is preferred.

Figure 4

Acceptability curve of the cost-effectiveness of adding magnetic resonance imaging (MRI) to standard risk stratification according to willingness to pay. The vertical axis represents the probability of cost-effectiveness, defined as producing an incremental cost-effectiveness ratio (ICER) below the willingness-to-pay threshold (in dollars per quality-adjusted life-years gained) listed on the horizontal axis for the MRI (solid line) and “treat all” (dotted line) strategies, respectively. For example, at an ICER threshold of $100 000 per quality-adjusted life-year gained, less than 10.0% of simulations yielded ICERs below $100 000 for the “treat all” strategy and less than 20.0% for the MRI strategy compared with standard risk stratification only.

Figure 5

Incremental cost-effectiveness ratio (ICER) scatterplot of adding magnetic resonance imaging (MRI) to standard risk stratification. Incremental effectiveness (in quality-adjusted life-years [QALYs]) and lifetime rheumatoid arthritis–related costs are plotted on the horizontal and vertical axes, respectively. Each dot represents the ICER for 1 simulation. The ellipse represents a 95% confidence ellipse around the ICERs (dots) for the MRI strategy compared with standard risk stratification only. The dashed line represents the commonly cited cost-effectiveness threshold of $100 000 per QALY gained, and every dot above this line exceeds this threshold. Therefore, only the dots located on the lower right of this diagonal dashed line represent cost-effective simulations for MRI compared with standard risk stratification at a threshold of $100 000 per QALY gained. These dots correlate with the less than 20.0% of simulations producing cost-effective ICERs for the MRI strategy in Figure 4. Data presented are for the lifetime analysis.