Abstract for: A Dynamic Model for Understanding Long-Term Trends in Prostate Cancer Screening
Widespread population screening for disease remains controversial. Whereas guidelines for routine screening should be based on medical evidence, evidence often has relatively low impact on practice and has led to ongoing controversy and conflict over appropriate guidelines among scientists, clinicians, and patient advocacy groups. There are significant variations in clinical practice, including evidence of over-screening for some diseases, and under-screening for some others. To explain the patterns of over/under screening, fluctuating guidelines, low adherence to guidelines, and conflict between scientists and other groups, I develop the first explicit broad boundary feedback theory of the dynamics of medical screening, tested in a formal mathematical model. The model presents an extended case study specific to PSA screening for prostate cancer, including realistic presentations for the fundamental tradeoff between test sensitivity and specificity, natural progression of the disease, and respective changes in population size and composition. While the screening debate is not specific to the United States, we mainly treat the problem within the U.S. context.