Optimal decision making in a dynamic model of community health

This paper presents results from a preliminary system dynamics simulation model of a hypothetical community in poor health and suffering from a "syndemic" of intertwined afflictions. Prevention science has moved from an emphasis on single diseases and epidemics toward a more systemic, ecological perspective, including the concept of causal feedback. From this perspective, afflictions may be seen as being affected by - but also as affecting over time - adverse living conditions and the community's internal capability to address its health and social problems. System dynamics provides a methodology for translating this feedback view into testable form and analyzing its implications, including those involving policy decisions. Our simulation model is relatively compact, containing only three stocks and about 100 variables overall, including some thirty constants that specify fixed aspects of the community, the cluster of afflictions, the effectiveness of problem-fighting efforts, and the cost-effectiveness of potential outside assistance from government and philanthropies. The model is based on the literature and the observations of public health officials, researchers, and community health advocates, but has not yet been verified and refined through case study application. Nonetheless, optimization and sensitivity testing of the model have generated logically defensible hypotheses about the dynamic impacts on community health of various types of outside assistance and their relative benefits. One such hypothesis is that the first priority for outside assistance in communities that are weak and struggling against multiple afflictions should be to assist in building community strength, perhaps even before substantial assistance is provided for direct fighting of prevalent diseases. Another possibility suggested by the model is that outside assistance aimed directly at improving living conditions may have downsides (time lags, unintended side effects) that render such assistance less beneficial in the absence of widespread citizen participation than other types of assistance for health improvement.