Letters Section Editor: Robert M. Golub, MD, Senior Editor.
In Reply: Citing data on driving distances, Dr Hanson argues that US residents may be less healthy due to a more sedentary lifestyle or greater pollution associated with more reliance on cars. Since the United States is spatially larger and less densely populated than England and because differences in driving distances partially reflect that, it is more useful to go directly to data on exercise and pollution. Among all conventional health risk factors, our inability to control for exercise is the most unfortunate. For example, even after controlling for body mass index, exercise is protective for diabetes because of its role in retarding the development of insulin resistance. The difficulty is that exercise was not defined in comparable ways in the 2 countries. Fortunately, starting in its 2004 wave, the Health Retirement Survey has adopted measures of exercise that more closely match those in the English Longitudinal Study of Aging (ELSA), which we intend to incorporate in future work.
Banks J, Marmot M, Oldfield Z, Smith JP. Comparison of Health Status Between the United States and England—Reply. JAMA. 2006;296(19):2312-2313. doi:10.1001/jama.296.19.2313-a