Cost-effectiveness of MRI compared to mammography for breast cancer screening in a high risk population

Abstract

Background: Breast magnetic resonance imaging (MRI) is a sensitive method of breast imaging virtually uninfluenced by breast density. Because of the improved sensitivity, breast MRI is increasingly being used for detection of breast cancer among high risk young women. However, the specificity of breast MRI is variable and costs are high. The purpose of this study was to determine if breast MRI is a cost-effective approach for the detection of breast cancer among young women at high risk.

Methods: A Markov model was created to compare annual breast cancer screening over 25 years with either breast MRI or mammography among young women at high risk. Data from published studies provided probabilities for the model including sensitivity and specificity of each screening strategy. Costs were based on Medicare reimbursement rates for hospital and physician services while medication costs were obtained from the Federal Supply Scale. Utilities from the literature were applied to each health outcome in the model including a disutility for the temporary health state following breast biopsy for a false positive test result. All costs and benefits were discounted at 5% per year. The analysis was performed from the payer perspective with results reported in 2006 U.S. dollars. Univariate and probabilistic sensitivity analyses addressed uncertainty in all model parameters.

Results: Breast MRI provided 14.1 discounted quality-adjusted life-years (QALYs) at a discounted cost of $18,167 while mammography provided 14.0 QALYs at a cost of $4,760 over 25 years of screening. The incremental cost-effectiveness ratio of breast MRI compared to mammography was $179,599/QALY. In univariate analysis, breast MRI screening became < $50,000/QALY when the cost of the MRI was < $315. In the probabilistic sensitivity analysis, MRI screening produced a net health benefit of -0.202 QALYs (95% central range: -0.767 QALYs to +0.439 QALYs) compared to mammography at a willingness-to-pay threshold of $50,000/QALY. Breast MRI screening was superior in 0%, < $50,000/QALY in 22%, > $50,000/QALY in 34%, and inferior in 44% of trials.

Conclusion: Although breast MRI may provide health benefits when compared to mammographic screening for some high risk women, it does not appear to be cost-effective even at willingness to pay thresholds above $120,000/QALY.

Figures

Figure 1

The Markov model. This model considers one cycle to be a full year, accounting for each time a patient underwent screening. Note that each breast is tracked independently, but patient state is determined by occurrence or no occurrence of cancer in the first breast.

Figure 2

Tornado diagram of univariate analyses. This Tornado diagram shows the degree to which uncertainty in individual variables affects ICER.

Figure 3

Incremental cost and effectiveness of MRI over mammography. This scatter plot shows the distribution of 10,000 trials form the Monte Carlo simulation.

Figure 4

Net health benefit acceptability curves. This graph shows the proportion of trials that attained cost-effectiveness for a given strategy for willingness-to-pay thresholds up to $200,000/QALY.