J Stockton

P65 Association of food outlet density and obesity: a cross-sectional study of urban areas in mexico

Background Obesity is an important and highly prevalent risk factor for non-communicable diseases in both developed and developing countries. Obesity prevalence is influenced by a complex, multifaceted system of determinants among which the food retailing and advertising environment is pivotal. Current food environments are often characterised by pervasive exposure to unprecedented availability and marketing of energy-rich and nutrient-poor foods. Mexico has one of the highest obesity rates in the world: 70% of the population is overweight or obese. The country has experienced a dietary and food retail transition involving increased high-calorie-dense food and drink availability. The aims of this study were 1) to analyse the associations between total food outlet density and BMI; 2) to examine the association of the retail food environment index (RFEI) and obesity; and 3) to study the association of the density of individual food outlets and obesity in Mexican adults in urban areas. Methods The National Institute of Statistics and Geography in Mexico provided geographical and food outlet data; BMI, calculated from anthropometric measurements, and socio-economic characteristics of a nationally-representative sample of adults aged 18+, came from participants in the National Health and Nutrition Survey in Mexico (ENSANUT) 2012. I calculated densities of supermarkets, restaurants, chain and non-chain convenience stores, and fruit and vegetable stores in total and by individual type per 1000 people per census tract area, using ArcGIS. I calculated RFEI, the ratio of ‘unhealthy’ to ‘healthy’ food outlets. Using multilevel linear regression, I analysed the relationship between density of food outlet types and obesity using complex survey design in STATA14. All analyses were adjusted for sex, age, socioeconomic status and physical activity. Results Both non-chain convenience store density [β=3.10, 95% CI 0.97 to 5.23, p=0.004] and non-chain combined with chain-type convenience store density [β=2.71, 95% CI 0.63 to 4.80, p=0.011] were significantly associated with obesity. Total food outlet density showed no significant association with obesity. However, the RFEI was associated with higher levels of obesity [β=0.040, 95% CI 0.00049 to 0.02, p=0.040]. Conclusion Convenience stores, which offer a greater availability of energy dense foods with low nutrient content, pose a risk to higher levels of obesity. A balance of healthier food outlets versus non-healthy food outlets could decrease the risk of obesity in urban areas of Mexico.

P136 Close residential proximity to busy roads may deter local walking among adults: Results from a survey of three Southeast England neighbourhoods

Background Traffic and transport infrastructure can signal an area’s socially beneficial economic vitality. They can also cause harm by inhibiting pedestrian mobility of nearby residents. Living near busy roads is associated with increased cardiovascular mortality. The pathways of community severance (the negative impacts of traffic and transport on local people’s health) are unclear owing to inadequate metrics. We investigated the association between residential proximity to busy roads and perceived ability to walk locally, using a novel cross-sectional survey developed to measure community severance. Methods Participants (N = 441; aged ≥18 y; 54% female) were randomly selected from addresses in three Southeast England neighbourhoods identified as likely to be affected by community severance, each bisected by a major road. A questionnaire was administered to measure participants’ demographic, socioeconomic and health characteristics, travel behaviours, and perceptions of neighbourhood traffic and transport infrastructure. Distance along the road and path network from each participant’s home address to their self-reported busiest local road was calculated using ArcGIS software. Associations between this distance and the extent to which traffic speed and volume affected participants’ perceived ability to walk locally were estimated by logistic regression. Results Traffic speed was reported by 23% of participants, and traffic volume by 24%, as often/ always affecting their ability to walk locally, and both factors were significantly associated with worse self-rated health. Compared with participants who lived >400 m from their busiest road (the reference category), those who lived ≤100 m from it had three times higher odds of reporting that their ability to walk locally was often/ always affected by traffic speed (OR 3.5, 1.7–6.9). A similar result was found for traffic volume (3.4, 1.7–6.8). These associations were attenuated after adjustment for demographic and socioeconomic factors (2.7, 1.3–5.6; 2.9, 1.4–6.0 respectively). Using the same reference group, the odds of participants living >100 m to ≤200 m from their busiest road reporting impaired walking were around twice as high for traffic speed (2.3, 1.1–4.8) and for volume (2.5, 1.2–5.1) but adjustment rendered these associations non-significant (1.6, 0.8–3.5; 1.9, 0.9–4.0 respectively). Conclusion Closer residential proximity to a road considered the busiest locally is associated with greater likelihood that local traffic speed and volume will often or always affect residents’ ability to walk in the area. Noise and air pollution likely explain much of the association between residential proximity to busy roads and poor health. A deterrent effect of busy roads on local walking, and therein health-promoting physical activity, warrants further investigation.

P54 The corner store: a major contributor to obesity in Mexico? Spatial analysis of the food environment and its association with obesity in Mexico

Background Obesity is a worldwide public health issue. Many factors contribute to this: a holistic approach is required to tackle it. Due to the rapid increase in obesity in many parts of the world, the food environment and its effect on obesity has been an increasing topic of study. Mexico has one of the highest prevalence rates of obesity in the world: 70% of the Mexican population is overweight or obese. Furthermore, the country has gone through a dietary and food retail transition. The aim of this ongoing study is to explore the association between the density of different food outlets and obesity in Mexican adults. Methods Geographical and food outlet data were obtained from the National Institute of Statistics and Geography in Mexico. For health data I used anthropometric measurements and socio-economic characteristics of adult participants (18+) from the National Health and Nutrition Survey in Mexico 2012. Densities of supermarkets, restaurants chain and non-chain convenience stores and fruit and vegetables stores were calculated per census tract area (CTA). Count of each food outlet type and the population in each CTA were used to calculate densities in ArcGIS. Regressions were undertaken to explore the association of BMI and the density of each food outlet type using complex survey design in STATA14. I classified CTAs as obesogenic or leptogenic according to the density and type of food outlets that predominated. All analyses were adjusted for sex, age, physical activity, socioeconomic status, education and deprivation. Results No significant associations were found between the density of supermarkets, fruit and vegetable stores, chain and non-chain convenience stores and obesity (BMI ≥ 30 kg/m2). However, the density of restaurants, including fast-food outlets, was significantly and negatively associated with obesity among women (β = −0.54 [95% CI −0.99, 0.08] P = 0.019). In regard to the food environment classification, CTAs that had a higher density of food outlets were also significantly and negatively associated with obesity (β = −1.43 [−2.18 to −0.68] P<0.01). Conclusion Food environments with a greater healthy food availability and diversity could be associated with lower BMIs. On the other hand, high density of food outlets which offer calorie-dense food, rich in saturated fats and high glycaemic foods and drinks, along with large portions could be a contributing factor to the problem of obesity in Mexico. Further geospatial analyses are ongoing.