Jamie Pearce

Neighbourhoods and health: a GIS approach to measuring community resource accessibility

Objective: Recent studies suggest an association between the contextual attributes of neighbourhoods and the health status of residents. However, there has been a scarcity of studies that have directly measured the material characteristics of neighbourhoods theorised to have an impact on health and health inequalities. This paper describes the development of an innovative methodology to measure geographical access to a range of community resources that have been empirically linked to health. Geographical information systems (GIS) were applied to develop precise measures of community resource accessibility for small areas at a national scale. Design: Locational access to shopping, education, recreation, and health facilities was established for all 38 350 census meshblocks across New Zealand. Using GIS, distance measures were calculated from the population weighted centroid of each meshblock to 16 specific types of facilities theorised as potentially health related. From these data, indices of community resource accessibility for all New Zealand neighbourhoods were constructed. Results: Clear regional variations in geographical accessibility to community resources exist across the country, particularly between urban and rural areas of New Zealand. For example, the average travel time to the nearest food shop ranged from less than one minute to more than 244 minutes. Noticeable differences were also apparent between neighbourhoods within urban areas. Conclusions: Recent advances in GIS and computing capacity have made it feasible to directly measure access to health related community resources at the neighbourhood level. The construction of access indices for specific community resources will enable health researchers to examine with greater precision, variations in the material characteristics of neighbourhoods and the pathways through which neighbourhoods impact on specific health outcomes.

The contextual effects of neighbourhood access to supermarkets and convenience stores on individual fruit and vegetable consumption

Background: It is often suggested that neighbourhood access to food retailers affects the dietary patterns of local residents, but this hypothesis has not been adequately researched. We examine the association between neighbourhood accessibility to supermarkets and convenience stores and individuals’ consumption of fruit and vegetables in New Zealand. Methods: Using geographical information systems, travel times from the population-weighted centroid of each neighbourhood to the closest supermarket and convenience store were calculated for 38 350 neighbourhoods. These neighbourhood measures of accessibility were appended to the 2002–3 New Zealand Health Survey of 12 529 adults. Results: The consumption of the recommended daily intake of fruit was not associated with living in a neighbourhood with better access to supermarkets or convenience stores. Similarly, access to supermarkets was not related to vegetable intake. However, individuals in the quartile of neighbourhoods with the best access to convenience stores had 25% (OR 0.75, 95% CI 0.60% to 0.93%) lower odds of eating the recommended vegetable intake compared to individuals in the base category (worst access). Conclusion: This study found little evidence that poor locational access to food retail provision is associated with lower fruit and vegetable consumption. However, before rejecting the commonsense notion that neighbourhood access to fruit and vegetables affects personal consumption, research that measures fruit and vegetable access more precisely and directly is required.

Role of physical activity in the relationship between urban green space and health

OBJECTIVES Local availability of green space has been associated with a wide range of health benefits. Possible causative mechanisms underpinning the green space and health relationship include the provision of physical activity opportunities, the stress-relieving effects of nature and the facilitation of social contacts. This study sought to investigate whether urban green space was related to individual-level health outcomes, and whether levels of physical activity were likely to be a mediating factor in any relationships found. STUDY DESIGN Cross-sectional analysis of anonymized individual health survey responses. METHODS Neighbourhood-level green space availability was linked to 8157 respondents to the New Zealand Health Survey 2006/07 on the basis of their place of residence. Adjusted multilevel models were constructed for four health outcomes which are plausibly related to green space via physical activity: cardiovascular disease; overweight; poor general health; and poor mental health (Short Form 36). RESULTS The greenest neighbourhoods had the lowest risks of poor mental health [odds ratio (OR) 0.81, 95% confidence interval (CI) 0.66-1.00]. Cardiovascular disease risk was reduced in all neighbourhoods with >15% green space availability (e.g. OR 0.80, 95% CI 0.64-0.99 for those with 33-70% green space), However, a dose-response relationship was not found. Green space availability was not related to overweight or poor general health. Overall, levels of physical activity were higher in greener neighbourhoods, but adjustment for this only slightly attenuated the green space and health relationships. CONCLUSIONS Neighbourhood green space was related to better cardiovascular and mental health in a New Zealand Health Survey, independent of individual risk factors. Although physical activity was higher in greener neighbourhoods, it did not fully explain the green space and health relationship.

Neighbourhood access to open spaces and the physical activity of residents: A national study

OBJECTIVE Increasing population levels of physical activity is high on the health agenda in many countries. There is some evidence that neighbourhood access to public open space can increase physical activity by providing easier and more direct access to opportunities for exercise. This national study examines the relationship between travel time access to parks and beaches, BMI and physical activity in New Zealand neighbourhoods. METHODS Access to parks and beaches, measured in minutes taken by a car, was calculated for 38,350 neighbourhoods nationally using Geographic Information Systems. Multilevel regression analyses were used to establish the significance of access to these recreational amenities as a predictor of BMI, and levels of physical activity and sedentary behaviour in the 12,529 participants, living in 1178 neighbourhoods, of the New Zealand Health Survey 2002/3. RESULTS Neighbourhood access to parks was not associated with BMI, sedentary behaviour or physical activity, after controlling for individual-level socio-economic variables, and neighbourhood-level deprivation and urban/rural status. There was some evidence of a relationship between beach access and BMI and physical activity in the expected direction. CONCLUSIONS This study found little evidence of an association between locational access to open spaces and physical activity.

Using Geographic Information Systems (GIS) to assess the role of the built environment in influencing obesity: a glossary

Features of the built environment are increasingly being recognised as potentially important determinants of obesity. This has come about, in part, because of advances in methodological tools such as Geographic Information Systems (GIS). GIS has made the procurement of data related to the built environment easier and given researchers the flexibility to create a new generation of environmental exposure measures such as the travel time to the nearest supermarket or calculations of the amount of neighbourhood greenspace. Given the rapid advances in the availability of GIS data and the relative ease of use of GIS software, a glossary on the use of GIS to assess the built environment is timely. As a case study, we draw on aspects the food and physical activity environments as they might apply to obesity, to define key GIS terms related to data collection, concepts, and the measurement of environmental features.

The association between green space and cause-specific mortality in urban New Zealand: an ecological analysis of green space utility

BackgroundThere is mounting international evidence that exposure to green environments is associated with health benefits, including lower mortality rates. Consequently, it has been suggested that the uneven distribution of such environments may contribute to health inequalities. Possible causative mechanisms behind the green space and health relationship include the provision of physical activity opportunities, facilitation of social contact and the restorative effects of nature. In the New Zealand context we investigated whether there was a socioeconomic gradient in green space exposure and whether green space exposure was associated with cause-specific mortality (cardiovascular disease and lung cancer). We subsequently asked what is the mechanism(s) by which green space availability may influence mortality outcomes, by contrasting health associations for different types of green space.MethodsThis was an observational study on a population of 1,546,405 living in 1009 small urban areas in New Zealand. A neighbourhood-level classification was developed to distinguish between usable (i.e., visitable) and non-usable green space (i.e., visible but not visitable) in the urban areas. Negative binomial regression models were fitted to examine the association between quartiles of area-level green space availability and risk of mortality from cardiovascular disease (n = 9,484; 1996 - 2005) and from lung cancer (n = 2,603; 1996 - 2005), after control for age, sex, socio-economic deprivation, smoking, air pollution and population density.ResultsDeprived neighbourhoods were relatively disadvantaged in total green space availability (11% less total green space for a one standard deviation increase in NZDep2001 deprivation score, p < 0.001), but had marginally more usable green space (2% more for a one standard deviation increase in deprivation score, p = 0.002). No significant associations between usable or total green space and mortality were observed after adjustment for confounders.ConclusionContrary to expectations we found no evidence that green space influenced cardiovascular disease mortality in New Zealand, suggesting that green space and health relationships may vary according to national, societal or environmental context. Hence we were unable to infer the mechanism in the relationship. Our inability to adjust for individual-level factors with a significant influence on cardiovascular disease and lung cancer mortality risk (e.g., diet and alcohol consumption) will have limited the ability of the analyses to detect green space effects, if present. Additionally, green space variation may have lesser relevance for health in New Zealand because green space is generally more abundant and there is less social and spatial variation in its availability than found in other contexts.

A national study of the association between neighbourhood access to fast-food outlets and the diet and weight of local residents

Differential locational access to fast-food retailing between neighbourhoods of varying socioeconomic status has been suggested as a contextual explanation for the social distribution of diet-related mortality and morbidity. This New Zealand study examines whether neighbourhood access to fast-food outlets is associated with individual diet-related health outcomes. Travel distances to the closest fast-food outlet (multinational and locally operated) were calculated for all neighbourhoods and appended to a national health survey. Residents in neighbourhoods with the furthest access to a multinational fast-food outlet were more likely to eat the recommended intake of vegetables but also be overweight. There was no association with fruit consumption. Access to locally operated fast-food outlets was not associated with the consumption of the recommended fruit and vegetables or being overweight. Better neighbourhood access to fast-food retailing is unlikely to be a key contextual driver for inequalities in diet-related health outcomes in New Zealand.

Obesity-Promoting Food Environments and the Spatial Clustering of Food Outlets Around Schools

BACKGROUND The increasing prevalence of overweight and obesity in school-aged children is potentially linked to contextual influences such as the food environment around schools. The proximity of fast-food and convenience stores to schools may enhance access to unhealthy foods and have a negative impact on diet. PURPOSE This study used spatial cluster analysis to determine whether food outlets are clustered around schools and evaluated the extent of food outlet clustering by school and school neighborhood sociodemographic characteristics. METHODS The locations in 2008 of all schools, fast-food outlets, and convenience stores in five urban regions across New Zealand were geocoded. Using GIS analysis conducted in 2009, the number and proportion of outlets within 400-m and 800-m road distance around each school was calculated. The spatial clustering of food outlets within 1.5 km of schools was determined using a multi-type K-function. Food outlet type, school level, SES, the degree of population density, and commercial land use zoning around each school were compared. RESULTS Primary/intermediate schools had a total proportion of 19.3 outlets per 1000 students within 800 m compared to 6.6 for secondary schools. The most socially deprived quintile of schools had three times the number and proportion of food outlets compared to the least-deprived quintile. There was a high degree of clustering of food outlets around schools, with up to 5.5 times more outlets than might be expected. Outlets were most clustered up to 800 m from schools and around secondary schools, socially deprived schools, and schools in densely populated and commercially zoned areas. CONCLUSIONS Food environments in New Zealand within walking proximity to schools are characterized by a high density of fast-food outlets and convenience stores, particularly in more-socially deprived settings. These obesogenic environments provide ready access to obesity-promoting foods that may have a negative impact on student diet and contribute to inequalities in health.

A national study of neighbourhood access to gambling opportunities and individual gambling behaviour

Objective: To investigate associations between neighbourhood accessibility to gambling outlets (non-casino gaming machine locations, sports betting venues and casinos) and individual gambling behaviour in New Zealand. Design: A Geographical Information Systems (GIS) measure of neighbourhood access to gambling venues. Two-level logistic regression models were fitted to examine the effects of neighbourhood access on individual gambling behaviour after controlling for potential individual- and neighbourhood-level confounding factors. Setting: 38 350 neighbourhoods across New Zealand. Participants: 12 529 respondents of the 2002/03 New Zealand Health Survey. Results: Compared with those living in the quartile of neighbourhoods with the furthest access to a gambling venue, residents living in the quartile of neighbourhoods with the closest access were more likely (adjusted for age, sex, socio-economic status at the individual-level and deprivation, urban/rural status at the neighbourhood-level) to be a gambler (OR 1.60, 95% CI 1.20 to 2.15) or problem gambler (OR 2.70, 95% CI 1.03 to 7.05). When examined independently, neighbourhood access to venues with non-casino gaming machines (gambling: OR 1.67, 95% CI 1.28 to 2.18; problem gambling: OR 2.71, 95% CI 1.45 to 5.07) and sports betting venues (gambling: OR 1.67, 95% CI 1.28 to 2.18; problem gambling: OR 2.71, 95% CI 1.45 to 5.07) were similarly related. Conclusions: Neighbourhood access to opportunities for gambling is related to gambling and problem gambling behaviour, and contributes substantially to neighbourhood inequalities in gambling over and above-individual level characteristics.

Neighborhood built environment and transport and leisure physical activity: findings using objective exposure and outcome measures in New Zealand.

Background: Evidence of associations between neighborhood built environments and transport-related physical activity (PA) is accumulating, but few studies have investigated associations with leisure-time PA. Objective: We investigated associations of five objectively measured characteristics of the neighborhood built environment—destination access, street connectivity, dwelling density, land-use mix and streetscape quality—with residents’ self-reported PA (transport, leisure, and walking) and accelerometer-derived measures of PA. Methods: Using a multicity stratified cluster sampling design, we conducted a cross-sectional survey of 2,033 adults who lived in 48 New Zealand neighborhoods. Multilevel regression modeling, which was adjusted for individual-level (sociodemographic and neighborhood preference) and neighborhood-level (deprivation) confounders, was used to estimate associations of built environment with PA. Results: We found that 1-SD increases in destination access, street connectivity, and dwelling density were associated with any versus no self-reported transport, leisure, or walking PA, with increased odds ranging from 21% [street connectivity with leisure PA, 95% confidence interval (CI): 0%, 47%] to 44% (destination accessibility with walking, 95% CI: 17%, 79%). Among participants who self-reported some PA, a 1-SD increase in street connectivity was associated with a 13% increase in leisure PA (95% CI: 0, 28%). SD increases in destination access, street connectivity, and dwelling density were each associated with 7% increases in accelerometer counts. Conclusions: Associations of neighborhood destination access, street connectivity, and dwelling density with self-reported and objectively measured PA were moderately strong, indicating the potential to increase PA through changes in neighborhood characteristics.