摘要：Objectives. We investigated whether moving to neighborhoods with closer proximity of destinations and greater street connectivity was associated with more walking, a greater probability of meeting the “Every Body Walk!” campaign goals (≥ 150 minutes/week of walking), and reductions in body mass index (BMI). Methods. We linked longitudinal data from 701 participants, who moved between 2 waves of the Multi-Ethnic Study of Atherosclerosis (2004–2012), to a neighborhood walkability measure (Street Smart Walk Score) for each residential location. We used fixed-effects models to estimate if changes in walkability resulting from relocation were associated with simultaneous changes in walking behaviors and BMI. Results. Moving to a location with a 10-point higher Walk Score was associated with a 16.04 minutes per week (95% confidence interval [CI] = 5.13, 29.96) increase in transport walking, 11% higher odds of meeting Every Body Walk! goals through transport walking (adjusted odds ratio = 1.11; 95% CI = 1.02, 1.21), and a 0.06 kilogram per meters squared (95% CI = −0.12, −0.01) reduction in BMI. Change in walkability was not associated with change in leisure walking. Conclusions. Our findings illustrated the potential for neighborhood infrastructure to support health-enhancing behaviors and overall health of people in the United States. A recent report by the National Academy of Sciences showed that people in the United States live shorter lives and have consistently worse health than people in other high-income countries. 1 A high burden of obesity, diabetes, and cardiovascular disease was identified as contributing to the United States’ health disadvantages. 1 The report encouraged researchers and policymakers to identify the environmental factors that might be contributing to a high prevalence of these conditions in the United States, including the extent to which environmental conditions common in many communities shape the behavioral antecedents of cardiovascular disease. Although international comparisons on levels of physical activity across countries are often inconclusive because of measurement differences, 2–4 the United States differs starkly from many other high-income countries in the extent to which residents engage in active travel, such as through walking or bicycling. For example, the overall bicycle share of work trips is currently 3 times higher in Canada than in the United States, 5 and the percentage of total trips by bicycle and foot are lower in the United States than in Ireland, France, Great Britain, Norway, Denmark, Finland, Germany, Sweden, Spain, Netherlands, and Switzerland. 6 Research indicates that walking is the most common leisure activity performed by adults and can be an important component of physical activity. 7–10 Consistent with this evidence, in April 2013, the US Surgeon General announced the “Every Body Walk!” campaign ( http://www.everybodywalk.org ) to promote walking as a simple and effective form of physical activity. The success of campaigns to promote walking is likely to be strongly influenced by whether environmental conditions make walking feasible and safe. 11–13 In 2 international studies across 11 countries, fewer US participants reported having many shops within walking distance or transit stops within 10 to 15 minutes of their home than their international peers. 13,14 A comparison of global cities between 1980 and 1990 also revealed that cities in the United States have accelerated dramatically in their dependence on the automobile, with little improvements in transit use, 15 and that per capita automobile use and average gasoline consumption in the United States are 2 times higher than those in Australian cities, 4 times higher than those in European cities, and 10 times higher than those in Asian cities. 15,16 Additional disparities within the United States exist, with rates of walking and bicycling differing across various cities and states 6 ; counties with high poverty and low education are less likely to implement local pedestrian- and bicycle-related projects using federal transportation funding. 17 Although several reviews indicate that measures of neighborhood walkability (such as self-reported walkability, accessibility to destinations, and street connectivity) are cross-sectionally associated with walking, 18–20 physical activity, 18,21–23 and body mass index (BMI), 21,24,25 these studies cannot be used to draw policy-relevant causal inferences partly because of the impossibility of determining the temporal relation between neighborhood walkability and walking behavior. 18–25 Studies that examine how changes in environmental conditions are related to changes in behaviors are therefore needed. A major challenge in estimating the causal effects of environments on health is accounting for the possibility that persons with predispositions to certain behaviors choose to live in certain types of neighborhoods. 26–31 Randomized studies of environmental interventions (such as increasing walkability) are logistically challenging and unlikely to be feasible on a large scale. Hence, reliance on rigorous use of observational data is necessary. Very few cohort studies have longitudinal assessments of changes in the environment to allow investigations of associations between neighborhood change and health-related outcomes. 32–34 Because built environments often change slowly, the impact can be practically examined by investigating changes occurring as part of residential relocation. 18,30,35–45 Although longitudinal studies do not completely overcome the effect of self-selection on the associations observed, 18 they have the potential to improve causal evidence, especially if they investigate the impact of changes in neighborhood conditions on changes in health. We used data from a population-based and multiethnic longitudinal study conducted in 6 diverse areas of the United States to investigate whether changes in environmental features associated with residential relocation were linked to simultaneous changes in walking for transport or for leisure in adults. The presence of such a relationship would provide strong support for consideration of land use, development, and transportation policies as levers to increase physical activity in the United States. More generally, it would lend greater credence to the notion that at least some of the US health disadvantages could be the unintended consequence of a range of policy and development decisions that engineered physically active lifestyles, such as walking, out of the lives of some US adults.
