Developing a Dynamic Model for Breast Cancer Screening Misperceptions and Feedback in Screening Mammography Debate: Anatomy of a Medical Decision

摘要

The debate about breast cancer screening has become so contentious that rational decision making has been compromised at both the individual and policy levels. The controversy is less about available scientific evidence than it is about (mis)perceptions, judgments and attitudes. There is disagreement about how to fairly describe the risk and how to avoid misperceptions that may distort real assessment of risk. The entire decision-making process has also been embedded in a highly charged socio-political system, dominated by single-issue advocacy groups. In this study we develop a feedback rich theory to explain the dynamic nature of the screening problem within the US context. Our model is tightly grounded in evidence base, parameterized for the US data and replicates the basic dynamics concerning breast cancer, including the diffusion dynamics for mammogram screening and the noncompliance with recommendations against screening. We demonstrate how a medical decision making-process is distorted by misperception of risks, over-awareness, and by other special features which further distort the quality of the discussion, like single-issue advocacy groups and gender politics. The entire system is shown to dynamically interact with available facts to cause a self-reinforcing over-awareness and over-screening trend for breast cancer in the US, which leads to over-diagnosis and over-treatment, i.e. the over-use of health services. The dominant feedbacks are shown to drive the system towards a balance that is not consistent with the optima. Lessons from this debate can be more generally applied to other policy problems that entail small degrees of risk and whose management is highly contentious. The dynamic model we developed for the screening problem can be used to enhance rational decision making and to improve the debate. It also provides an experimental platform to gain important insights into other policy issues in which there is, at very substantial cost, a huge benefit for only a few and a small amount of harm for a larger number of people.