Budget impact analysis of switching to digital mammography in a population-based breast cancer screening program: a discrete event simulation model

Abstract

Objective: To assess the budgetary impact of switching from screen-film mammography to full-field digital mammography in a population-based breast cancer screening program.

Methods: A discrete-event simulation model was built to reproduce the breast cancer screening process (biennial mammographic screening of women aged 50 to 69 years) combined with the natural history of breast cancer. The simulation started with 100,000 women and, during a 20-year simulation horizon, new women were dynamically entered according to the aging of the Spanish population. Data on screening were obtained from Spanish breast cancer screening programs. Data on the natural history of breast cancer were based on US data adapted to our population. A budget impact analysis comparing digital with screen-film screening mammography was performed in a sample of 2,000 simulation runs. A sensitivity analysis was performed for crucial screening-related parameters. Distinct scenarios for recall and detection rates were compared.

Results: Statistically significant savings were found for overall costs, treatment costs and the costs of additional tests in the long term. The overall cost saving was 1,115,857€ (95%CI from 932,147 to 1,299,567) in the 10th year and 2,866,124€ (95%CI from 2,492,610 to 3,239,638) in the 20th year, representing 4.5% and 8.1% of the overall cost associated with screen-film mammography. The sensitivity analysis showed net savings in the long term.

Conclusions: Switching to digital mammography in a population-based breast cancer screening program saves long-term budget expense, in addition to providing technical advantages. Our results were consistent across distinct scenarios representing the different results obtained in European breast cancer screening programs.

Figure 1. Flow chart of the conceptual model (screening [a] and natural history of cancer [b]).

TN: true negative, FP: false positive, TP: true positive, FN: false negative.

Figure 2. Budget impact analysis.

Differences in cost between screen-film and digital mammography, by type of cost and year. Positive differences indicate cost savings with digital mammography.

Figure 3. Sensitivity analysis results.

DM better (n = 921 runs): Digital mammography higher detection rate and lower recall rate, or digital higher detection rate and similar recall rate, or digital lower recall rate and similar detection rate. SFM better (n = 469 runs): Screen-film mammography higher detection rate and lower recall rate, or SFM higher detection rate and similar recall rate, or SFM lower recall rate and similar detection rate. Intermediate scenario (n = 610 runs, not shown): Digital higher detection rate and SFM lower recall rate, or digital lower recall rate and SFM higher detection rate, or both similar detection and recall rates. CI: Confidence Interval.