Decrease in U.S. Deaths from Coronary Disease

To the Editor: Ford et al. (June 7 issue)1 have developed a statistical model, called IMPACT, which explains almost 90% of the observed decrease in deaths from coronary heart disease in the United States in the 20 years from 1980 to 2000. This model, which has been validated and reproduced mainly in developed countries, is so robust that some of its findings are similar to those of the earlier Nurses' Health Study,2 especially the proportional contributions of smoking and obesity to heart disease (13% and 8%, respectively). However, the model does not explain almost 10% of the observed decrease in deaths. The reduction in particulate air pollution, for example, explains from 18 to 76% of the decline in deaths from both coronary heart disease and coronary vascular disease.3,4 No doubt the U.S. outdoor air quality has improved substantially since 1980. An Irish study performed after the ban on burning coal showed a 10% decline in deaths from coronary vascular disease.5 Therefore, it would be worth considering air pollution in the IMPACT model, data that could be integrated into a comprehensive Chronic Disease Risk Model, thereby using such "gold standard" dynamic epidemiologic models as population-specific, evidence-based policy models.


Zubair Kabir, M.D., Ph.D.
Harvard School of Public Health
Boston, MA 02115
zkabir@hsph.harvard.edu