1. . Associations between natural amenities, physical activity, and body mass index in rural and urban North Carolina counties Stephanie B. Jilcott 1, PhD, Justin B. Moore 1, MS, PhD, Kindal A. Shores 2, PhD, Satomi Imai 1, PhD, David A. McGranahan 3, PhD 1 Department of Public Health, Brody School of Medicine, and 2 Department of Recreation and Leisure Studies, East Carolina University 3 Economic Research Service, United States Department of Agriculture American Public Health Association, November 9 th, 2010 Introduction Methods Results Conclusions References Area natural amenities (NA),including pleasant climate, 1 topographical variation, 2 and proximity to water, 3 have been linked to greater physical activity (PA) and lower body mass index (BMI) among local residents. The mechanisms linking NA to lower BMI are unclear. A study testing the mediating effect of PA on the association between green space and general health, was inconclusive. 4 The Natural Amenities Scale (NAS) is a composite, objective composite measure of the pleasantness of the local physical environment. 5 There are 2 implications stemming from examination of relationships between natural amenities, PA, and BMI: (1)From an epidemiological perspective, natural amenities may moderate relationships between the built environment and both PA and BMI. (2)If low-income and minority residents are more likely to live in areas with fewer natural amenities, socio-economic health disparities may be compounded by residential location. Therefore, the purpose of this analysis was to examine associations between county-level natural amenities, PA, and mean weighted BMI among all 100 counties in North Carolina (NC). The Natural Amenities Scale: sum of six items, including average January temperature, average January days of sun, low January to July average temperature gain, low average July humidity, topographical variation, and the ratio of water area to land area. Covariates: Percentage of rural residents, percentage of black residents, median age, and median household income, obtained from Census 2000 via the “Log in to North Carolina” (LINC) website (http://linc.state.nc.us/).http://linc.state.nc.us/ Self-reported PA: From NC Behavioral Risk Factor Surveillance System (BRFSS). Percent meeting the PA levels recommended at the time of the survey (moderate PA for 30 minutes/ day or vigorous PA for 20 minutes/day), termed “percent meeting PA criteria.” County-level mean weighted BMI: Self-reported height and weight from NC BRFSS. BRFSS data were analyzed using SUDAAN. BRFSS data combined for years 2003, 2005, and 2007, in order to obtain stable estimates for counties with fewer sampled individuals. Examined bivariate associations between county-level natural amenities, PA, mean weighted BMI, and all covariates using Pearson correlation coefficients. Counties were weighted by population. Used linear regression analyses, with backwards elimination of non- significant covariates, to examine the association between BMI and natural amenities. As rural and minority individuals may have less access to recreation facilities and thus be more dependent on a supportive natural environment, we stratified analyses by counties above and below the median for proportion of rural residents (= 0.62) and above and below the median for proportion of black residents (= 0.22). Natural amenities were negatively correlated with the percent black residents and BMI, and positively correlated with median age and percent meeting PA criteria. (Table) County-level mean weighted BMI was positively correlated with percent rural, percent black, and median age, and negatively correlated with median household income, natural amenities, and percent meeting PA criteria. (Table) Table. Correlation between percent rural, percent black, median age, median household income, natural amenities, percent meeting PA criteria, and BMI (N=100). % rural % black Median age Median HH income Natural Amen- ities % meeting PA criteria BMI Percent rural---0.20* 0.52***-0.67*** 0.07-0.18 0.46*** Percent black---0.35**-0.10-0.62***-0.37** 0.33** Median age---0.32** 0.38***-0.20* 0.19* Median household income-- 0.07 0.23*-0.51*** Natural amenities-- 0.33**-0.36** Percent meeting PA criteria---0.45*** BMI-- *p<=0.05 **p<=0.001 ***p<=0.0001 In adjusted linear regression models, controlling for percent black and median age, the percent meeting PA criteria and natural amenities were positively associated (parameter estimate = 1.42 (0.56), p = 0.013). BMI and natural amenities were significantly negatively associated, when controlling for percent rural, percent black, and median household income (parameter estimate = -0.13 (0.06), p = 0.026). When multivariate analyses were stratified by proportion of rural residents, the significant relationship between natural amenities and BMI was attenuated for the less rural counties and remained significant for the more rural counties. When analyses were stratified by proportion of black residents, the significant relationship between natural amenities and BMI was attenuated for the counties with a lower proportion of black residents and remained significant for counties with a greater proportion. The current study provides support for the notion that an appealing natural environment is associated with a healthier weight. In the current analysis, holding all covariates constant, the difference in county-level mean weighted BMI between the lowest 10% for natural amenities score (-1.42) versus the highest 10% (2.20) is 0.47 kg/ m 2. Relationships between BMI and natural amenities were stronger in counties with greater proportions of minority and rural residents. Limitations: Ecological research design; data aggregated over multiple years; lack of control for self-selection of residents into counties. Future work should determine if disadvantaged residents are more likely to live in areas with fewer amenities,and if such residents are more dependent on a supportive PA environment. 1. Lin G, Spann S, Hyman D, Pavlik V. Climate amenity and BMI.[erratum appears in Obesity (Silver Spring). 2007 Oct;15(10):2520]. Obesity 2007;15(8):2120-7. 2. McGinn AP, Evenson KR, Herring AH, Huston SL. The relationship between leisure, walking, and transportation activity with the natural environment. Health Place. 2007;13(3):588-602. 3. Witten K, Hiscock R, Pearce J, Blakely T. Neighbourhood access to open spaces and the physical activity of residents: a national study. Prev Med. 2008;47(3):299-303. 4. Maas J, Verheij RA, Spreeuwenberg P, Groenewegen PP. Physical activity as a possible mechanism behind the relationship between green space and health: a multilevel analysis. BMC Public Health. 2008;8:206. 5. McGranahan D. Natural Amenities Drive Rural Population Change. In: Economic Research Service, United States Department of Agriculture; 1999. *Disclaimer: The views expressed here are those of the authors, and may not be attributed to the Economic Research Service or the U.S. Department of Agriculture.