Is there an association between spatial access to parks/green space and childhood overweight/obesity in Calgary, Canada?

International Journal of Behavioral Nutrition and Physical Activity Is there an association between spatial access to parks/green space and childhood overweight/obesity in Calgary, Canada? Melissa L Potestio 2 Alka B Patel 2 Christopher D Powell 1 Deborah A McNeil 0 R Daniel Jacobson 3 Lindsay McLaren 2 0 University of Calgary, Faculty of Nursing and Population and Public Health, Alberta Health Services , 2888 Shaganappi Trail NW Calgary, Alberta, T3B 6A8 , Canada 1 University of Calgary, Bachelor of Health Sciences program, (at time of writing) Faculty of Medicine , 3330 Hospital Drive NW Calgary, Alberta, T2N 4N1 , Canada 2 University of Calgary, Department of Community Health Sciences, Faculty of Medicine , 3330 Hospital Drive NW Calgary, Alberta, T2N 4N1 , Canada 3 University of Calgary, Department of Geography, Faculty of Social Sciences , 2500 University Drive NW, Calgary, AB, T2N 1N4 , Canada Background: The recent increase in childhood obesity is expected to add significantly to the prevalence of chronic diseases. We used multivariate multilevel analysis to examine associations between parks/green space and childhood overweight/obesity across communities in Calgary, Canada, a city characterized by intensified urban sprawl and high car use. Methods: Body Mass Index was calculated from measured height and weight data obtained from 6,772 children (mean age = 4.95 years) attending public health clinics for pre-school vaccinations. Each child's home postal code was geocoded using ESRI ArcGIS 9.2. We examined four measures of spatial access to parks/green space (based on Geographic Information Systems): 1) the number of parks/green spaces per 10,000 residents, 2) the area of parks/green space as a proportion of the total area within a community, 3) average distance to a park/green space, and 4) the proportion of parks/green space service area as a proportion of the total area within a community. Analyses were adjusted for dissemination area median family income (as a proxy for an individual child's family income) community-level education, and community-level proportion of visible minorities. Results: In general, parks/green space at the community level was not associated with overweight/ obesity in Calgary, with the exception of a marginally significant effect whereby a moderate number of parks/green spaces per 10,000 residents was associated with lower odds of overweight/obesity. This effect was non-significant in adjusted analyses. Conclusion: Our null findings may reflect the popularity of car travel in Calgary, Canada and suggest that the role built environment characteristics play in explaining health outcomes may differ depending on the type of urban environment being studied. - Background Recently the public health literature has seen an increasing number of studies investigating the relationship between various attributes of place and the health of populations [1-5]. This type of research strives to explain geographic variations in health outcomes as a function of both place and the individual characteristics of people living in that place [6,7]. As one example, there has been growing interest in understanding the role of residential environments in enhancing and constraining physical activity and influencing obesity[8]. This is particularly relevant considering evidence of a notable increase in the prevalence of obesity in Canadian children over recent decades[9,10]. Increasing prevalence of childhood obesity raises concern because childhood obesity has implications for health during childhood and into adulthood[11,12]. Increased childhood BMI, which often tracks into adulthood, has an important influence on adult morbidity, notably for cardiovascular disease, diabetes, and some cancers[12]. The increasing prevalence of pediatric obesity has drawn attention to children's decreasing physical activity levels[13]. Research has shown that physical activity levels established in youth tend to track into adulthood, and physical activity promotion in youth may facilitate a carryover of healthful habits into adulthood[14]. Promotion of physical activity is therefore a priority in current public health policies. However, to promote physical activity among children, its determinants need to be understood. From an ecological perspective, behaviours are not only affected by personal characteristics (e.g., age) but by interactions with the larger social and cultural contexts in which children live [15-17]. Research to test assertions of this perspective have examined how aspects of the built environment put some children at increased risk for obesity by encouraging the consumption of energy-dense foods and discouraging physical activity[15,17-19]. Disparities in chronic disease risk factors, such as obesity, may be partially attributed to neighbourhood environments that are poor in resources that could support healthy behaviours[20]. Neighbourhoods may have an impact on obesity and related health behaviours of young children in particular, as they spend much time in these environments[21]. For example, Liu and colleagues (2007) concluded that after controlling for individual socio-demographic variables and neighbourhood socioeconomic status, measures of decreased vegetation significantly predicted overweight in children [22]. A Canadian study explored whether aspects of neighbourhood design and spatial access to physical activity facilities were associated with body weight status among young children and found that increased walkability of neighbourhoods and intersection density were associated with lower odds of being overweight/obese among preschool girls but not boys[23]. Another Canadian study found that after controlling for individual/family factors, children living in the 'lowest-income' (i.e., largest proportion of people living below the low income cut-off) neighbourhood had an increasing BMI percentile over time compared to those children living in a 'middle-income' neighbourhood[24]. However, the mechanisms by which this occurred are unclear. Ferreira and colleagues (2006) conducted a systematic review on environmental correlates of youth physical activity[25]. Among these studies, features of the built environment such as access to equipment, facilities, or programmes were investigated most often, but were generally unrelated to physical activity. However, other studies that measured spatial access to recreational facilities, including parks, have shown that access is associated with increased physical activity in youth [26-28]. Some studies that examine the association between spatial access, measured either objectively or subjectively, to various types of recreational space (e.g., indoor facilities, outdoor parks) and childhood overweight/obesity status, show significant inverse associations [26,27]. For example, Veugelers and colleagues (2008) found that grade five children in Nova Scotia, Canada, who lived in neighbourhoods where parents p (...truncated)