摘要：Objectives. We used cartograms to visually communicate the state-specific prevalence of obesity and its association with socioeconomic variables over time to benefit and inform decisions by national health policymakers who address geographic and social inequities in health. Methods. We generated density-equalizing maps, known as cartograms (in which geographic regions are sized in proportion to some variable), that illustrate indicators of population and educational attainment. We also provide an innovative presentation of the obesity choropleth map (which presents values for areas by shading). Results. The maps depict the absolute burden of obesity, the inverse association between obesity and education, and geographic patterns in the prevalence of obesity over time. Conclusions. The prevalence of obesity in the United States continues to increase. These cartograms can help stakeholders interpret surveillance data and their relation to demographic and socioeconomic characteristics to inform decisions. Several national surveys have shown that prevalence rates for obesity continue to increase. 1 , 2 Not surprisingly, this prevalence is not uniformly distributed; obesity disproportionately affects some groups in the United States. 3 , 4 Among adult men, no significant differences in obesity prevalence are seen among racial/ethnic groups. 1 , 5 , 6 However, both non-Hispanic Black and Mexican American women have a higher prevalence of obesity. 1 , 5 , 6 Among adult women, poverty and low educational levels are also associated with a higher prevalence of obesity. 5 Data from public health surveillance, often summarized in large, traditional tables, can be difficult to interpret and may not show the information in a meaningful way. One common solution is to display trends in the prevalence of obesity via maps. For instance, researchers have used choropleth maps (which present percentages for areas through the use of color, saturation, and lightness) to show changes in state-specific prevalence of obesity over time. 7 Several limitations and critiques have been noted for choropleth maps, however. 8 , 9 For example, large areas (often sparsely populated) tend to visually dominate smaller (often densely populated) areas, 10 – 14 leading to potential misinterpretation of the burden of obesity. Moreover, obesity is most highly concentrated among certain subpopulations, not only minorities but also the poor, 15 and these related factors are difficult to depict on choropleth maps. The use of density-equalizing maps, or cartograms, minimizes such limitations by transforming the size and sometimes the shape of political areas (in this case, states) so they are proportional to another variable; traditionally, the variable is population, but other variables could be used. Cartograms are relatively new to public health but have been used successfully to map patterns of chronic disease, including the distribution of Wilms tumors in New York State, 16 mortality patterns of cerebrovascular disease in North Carolina, 17 and associations between both lung cancer and leukemia and the Rocky Flats plant site in Colorado. 10 Other successful cartograms have been developed to analyze the spatial distribution of cryptosporidiosis among AIDS patients in San Francisco, California, 18 and to characterize the spatial distribution of late-state and in situ breast cancer among women in the San Francisco Bay Area. 19 Innovative mapping applications, including cartograms, can be used in public health to improve understanding of health problems and for exploratory analysis of data. 20 , 21 For our exploratory study, we used cartograms and other cartographic techniques to visually communicate the pattern of obesity prevalence and its association with socioeconomic variables over time. Our density-equalizing cartograms of population and education indicators show the prevalence of obesity, and an innovative presentation of the choropleth map shows change in obesity prevalence over time.
