Volume 4: No. 3, July 2007
Charting Plausible Futures for Diabetes Prevalence in the United States: A Role for System Dynamics Simulation Modeling
Figure 1 graphs the trend of diabetes prevalence between 1980 and 2003, along with
Healthy People objectives for 2000 and 2010 as well as simulation results from three experiments discussed in the narrative. The x axis is calibrated for years between 1980 and 2010. The y axis indicates the number of people with diagnosed diabetes per 1000 population. It is labeled in increments of ten. Three prevalence lines are graphed: (1) reported, (2)
Healthy People objectives, and (3) simulated scenarios.
Figure 1 gives the following data points:
Reported prevalence: 1987, 33.8; 1997, 39.2; 2000, 44.6; in 2003, 48.9 Healthy People objective: 2000, 30.8; 2010, 25.0 Simulated: in 2010, 59.1 under the status quo scenario; 63.2 under meets the
Healthy People detection objective 5-4 scenario; 52.3 under the meets
Healthy People onset objective 5-2 scenario.
Figure 1. Diagnosed prevalence of diabetes per 1000 total population, United States, 1980–2003 (8), with
Healthy People 2000 and
Healthy People 2010 objectives (2,3), and simulation model output, 2003–2010 (13).
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Figure 2 is a stock-and-flow diagram describing the incidence, diagnosis, and prevalence of a disease in a population. It includes three mutually exclusive population stocks as well as the related rates of change among them.
The first stock, labeled Population Without Disease, has a single outflow for the rate of People Developing Disease (or initial onset), which in turn, is the only inflow into the stock of Undiagnosed Prevalence. Undiagnosed Prevalence has a single outflow rate for Diagnosed Onset, leading to the final stock of Diagnosed Prevalence.
There are two outflows from Diagnosed Prevalence, one for deaths and another for recovery, which returns people back to the Population without Disease.
Figure 2. Generic stock-and-flow structure for diagnosed prevalence of a disease.
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