Conceptualization and measurement of environmental exposure in epidemiology: Accounting for activity space related to daily mobility

A systematic review of correlates of sedentary behaviour in adults aged 18-65 years: a socio-ecological approach

Background

Recent research shows that sedentary behaviour is associated with adverse cardio-metabolic consequences even among those considered sufficiently physically active. In order to successfully develop interventions to address this unhealthy behaviour, factors that influence sedentariness need to be identified and fully understood. The aim of this review is to identify individual, social, environmental, and policy-related determinants or correlates of sedentary behaviours among adults aged 18–65 years.

Methods

PubMed, Embase, CINAHL, PsycINFO and Web of Science were searched for articles published between January 2000 and September 2015. The search strategy was based on four key elements and their synonyms: (a) sedentary behaviour (b) correlates (c) types of sedentary behaviours (d) types of correlates. Articles were included if information relating to sedentary behaviour in adults (18–65 years) was reported. Studies on samples selected by disease were excluded. The full protocol is available from PROSPERO (PROSPERO 2014:CRD42014009823).

Results

74 original studies were identified out of 4041: 71 observational, two qualitative and one experimental study. Sedentary behaviour was primarily measured as self-reported screen leisure time and total sitting time. In 15 studies, objectively measured total sedentary time was reported: accelerometry (n = 14) and heart rate (n = 1). Individual level factors such as age, physical activity levels, body mass index, socio-economic status and mood were all significantly correlated with sedentariness. A trend towards increased amounts of leisure screen time was identified in those married or cohabiting while having children resulted in less total sitting time. Several environmental correlates were identified including proximity of green space, neighbourhood walkability and safety and weather.

Conclusions

Results provide further evidence relating to several already recognised individual level factors and preliminary evidence relating to social and environmental factors that should be further investigated. Most studies relied upon cross-sectional design limiting causal inference and the heterogeneity of the sedentary measures prevented direct comparison of findings. Future research necessitates longitudinal study designs, exploration of policy-related factors, further exploration of environmental factors, analysis of inter-relationships between identified factors and better classification of sedentary behaviour domains.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-016-2841-3) contains supplementary material, which is available to authorized users.

Destinations That Older Adults Experience Within Their GPS Activity Spaces Relation to Objectively Measured Physical Activity

Identifying the relevant geography is an ongoing obstacle to effectively evaluate the influence of neighborhood built environment on physical activity. We characterized density and diversity of destinations that 77 older adults experienced within individually representative GPS activity spaces and traditional residential buffers and assessed their associations with accelerometry-measured physical activity. Traditional residential buffers had lower destination density and diversity than activity spaces. Activity spaces based only on pedestrian and bicycling trips had higher destination densities than all-mode activity spaces. Regardless of neighborhood definition, adjusted associations between destinations and physical activity generally failed to reach statistical significance. However, within pedestrian and bicycling-based activity spaces each additional destination type was associated with 243.3 more steps/day (95% confidence interval (CI) 36.0, 450.7). Traditional buffers may not accurately portray the geographic space or neighborhood resources experienced by older adults. Pedestrian and bicycling activity spaces elucidate the importance of destinations for facilitating active transportation.

Assessing opportunities for physical activity in the built environment of children: interrelation between kernel density and neighborhood scale

BACKGROUND

Built environment studies provide broad evidence that urban characteristics influence physical activity (PA). However, findings are still difficult to compare, due to inconsistent measures assessing urban point characteristics and varying definitions of spatial scale. Both were found to influence the strength of the association between the built environment and PA.

METHODS

We simultaneously evaluated the effect of kernel approaches and network-distances to investigate the association between urban characteristics and physical activity depending on spatial scale and intensity measure. We assessed urban measures of point characteristics such as intersections, public transit stations, and public open spaces in ego-centered network-dependent neighborhoods based on geographical data of one German study region of the IDEFICS study. We calculated point intensities using the simple intensity and kernel approaches based on fixed bandwidths, cross-validated bandwidths including isotropic and anisotropic kernel functions and considering adaptive bandwidths that adjust for residential density. We distinguished six network-distances from 500 m up to 2 km to calculate each intensity measure. A log-gamma regression model was used to investigate the effect of each urban measure on moderate-to-vigorous physical activity (MVPA) of 400 2- to 9.9-year old children who participated in the IDEFICS study. Models were stratified by sex and age groups, i.e. pre-school children (2 to <6 years) and school children (6-9.9 years), and were adjusted for age, body mass index (BMI), education and safety concerns of parents, season and valid weartime of accelerometers.

RESULTS

Association between intensity measures and MVPA strongly differed by network-distance, with stronger effects found for larger network-distances. Simple intensity revealed smaller effect estimates and smaller goodness-of-fit compared to kernel approaches. Smallest variation in effect estimates over network-distances was found for kernel intensity measures based on isotropic and anisotropic cross-validated bandwidth selection.

CONCLUSION

We found a strong variation in the association between the built environment and PA of children based on the choice of intensity measure and network-distance. Kernel intensity measures provided stable results over various scales and improved the assessment compared to the simple intensity measure. Considering different spatial scales and kernel intensity methods might reduce methodological limitations in assessing opportunities for PA in the built environment.

Accounting for the daily locations visited in the study of the built environment correlates of recreational walking (the RECORD Cohort Study)

BACKGROUND

Understanding how built environment characteristics influence recreational walking is of the utmost importance to develop population-level strategies to increase levels of physical activity in a sustainable manner.

PURPOSE

This study analyzes the residential and non-residential environmental correlates of recreational walking, using precisely geocoded activity space data.

METHODS

The point-based locations regularly visited by 4365 participants of the RECORD Cohort Study (Residential Environment and CORonary heart Disease) were collected between 2011 and 2013 in the Paris region using the VERITAS software (Visualization and Evaluation of Regular Individual Travel destinations and Activity Spaces). Zero-inflated negative binomial regressions were used to investigate associations between both residential and non-residential environmental exposure and overall self-reported recreational walking over 7 days.

RESULTS

Density of destinations, presence of a lake or waterway, and neighborhood education were associated with an increase in the odds of reporting any recreational walking time. Only the density of destinations was associated with an increase in time spent walking for recreational purpose. Considering the recreational locations visited (i.e., sports and cultural destinations) in addition to the residential neighborhood in the calculation of exposure improved the model fit and increased the environment-walking associations, compared to a model accounting only for the residential space (Akaike Information Criterion equal to 52797 compared to 52815).

CONCLUSIONS

Creating an environment supportive to walking around recreational locations may particularly stimulate recreational walking among people willing to use these facilities.

Does the effect of walkable built environments vary by neighborhood socioeconomic status?

OBJECTIVE

To examine socioeconomic status as a moderator of the relationship between the built environment and active transportation such as walking or cycling using measures of built environment exposure derived from individuals transport trips.

METHODS

The 2008 Montreal Origin-destination (OD) survey provided origin-destination coordinates for a sample of 156,700 participants. We selected participants from this survey that had traveled within the census metropolitan area of Montreal the day preceding the interview, and that were between 18-65 years of age. Measures of connectivity, land-use mix, and density of business and services were collected using 400-m buffers of the trip routes. Logistic regression was used to model the relationship between built environment variables and active transportation.

RESULTS

Trip routes in the 2nd, 3rd, and 4th quartile of density of business and services or connectivity translated into greater odds of taking AT (compared to a trip in the lowest quartile). Trip routes in the 2nd, 3rd, and 4th quartile of land-use mix translated into lower odds of taking AT. Trips in the highest quartiles of connectivity and density of business and services were found to have a weaker association with active transportation if the individual undergoing the trip was from a low SES neighborhood.

CONCLUSION

Our results suggest that previous studies finding no effect modification may have been due to the limitation of measurements of exposures to the residential neighborhood.

Putting Families Into Place: Using Neighborhood-Effects Research and Activity Spaces to Understand Families

Neighborhood is an important context in which individuals and families are embedded. Yet family studies researchers have been relatively slow to incorporate spatial approaches into family science. Although limited theoretical and methodological attention has been devoted to families in neighborhood-effects research, family scholars can contribute greatly to theories about neighborhood effects, and neighborhood-effects research can help move the field of family studies forward. This article reviews the theories, applications, and limitations of research on neighborhood effects and discusses how family studies can benefit from incorporating a spatial perspective from neighborhood-effects research. I then present an innovative methodology-referred to as activity spaces-emerging in neighborhood-effects research, and I discuss how this approach can be used to better understand the complexity and heterogeneity of families. Last, I highlight ways to incorporate space into family studies by "putting families into place."

A qualitative geographical information systems approach to explore how older people over 70 years interact with and define their neighbourhood environment

A growing body of literature explores the relationship between the built environment and health, and the methodological challenges of understanding these complex interactions across the lifecourse. The impact of the neighbourhood environment on health and behaviour amongst older adults has received less attention, despite this age group being potentially more vulnerable to barriers in their surrounding social and physical environment. A qualitative geographical information systems (QGIS) approach was taken to facilitate the understanding of how older people over 70 in 5 UK towns interact with their local neighbourhood. The concept of neighbourhood changed seasonally and over the lifecourse, and was associated with social factors such as friends, family, or community activities, rather than places. Spaces stretched further than the local, which is problematic for older people who rely on variable public transport provision. QGIS techniques prompted rich discussions on interactions with and the meanings of ‘place’ in older people.

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Neighbourhoods become increasingly important to older people's wellbeing.

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Older people associate neighbourhood with people and activities rather than places.

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Neighbourhoods are dynamic; change seasonally and over the lifecourse.

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Qualitative GIS produces rich data on older people's interactions with place and space.

Multiple contexts of exposure: Activity spaces, residential neighborhoods, and self-rated health

Although health researchers have made progress in detecting place effects on health, existing work has largely focused on the local residential neighborhood and has lacked a temporal dimension. Little research has integrated both time and space to understand how exposure to multiple contexts - where adults live, work, shop, worship, and seek healthcare - influence and shape health and well-being. This study uses novel longitudinal data from the Los Angeles Family and Neighborhood Survey to delve deeper into the relationship between context and health by considering residential and activity space neighborhoods weighted by the amount of time spent in these contexts. Results from multilevel cross-classified logistic models indicate that contextual exposure to disadvantage, residential or non-residential, is independently associated with a higher likelihood of reporting poor or fair health. We also find support for a contextual incongruence hypothesis. For example, adults living in the most disadvantaged neighborhoods are more likely to report poor or fair health when they spend time in more advantaged neighborhoods than in more disadvantaged ones, while residents of more advantaged neighborhoods report worse health when they spend time in more disadvantaged areas. Our results suggest that certain types of place-based cumulative exposures are associated with a sense of relative neighborhood deprivation that potentially manifests in worse health ratings.

Theory and data for simulating fine-scale human movement in an urban environment

Individual-based models of infectious disease transmission depend on accurate quantification of fine-scale patterns of human movement. Existing models of movement either pertain to overly coarse scales, simulate some aspects of movement but not others, or were designed specifically for populations in developed countries. Here, we propose a generalizable framework for simulating the locations that an individual visits, time allocation across those locations, and population-level variation therein. As a case study, we fit alternative models for each of five aspects of movement (number, distance from home and types of locations visited; frequency and duration of visits) to interview data from 157 residents of the city of Iquitos, Peru. Comparison of alternative models showed that location type and distance from home were significant determinants of the locations that individuals visited and how much time they spent there. We also found that for most locations, residents of two neighbourhoods displayed indistinguishable preferences for visiting locations at various distances, despite differing distributions of locations around those neighbourhoods. Finally, simulated patterns of time allocation matched the interview data in a number of ways, suggesting that our framework constitutes a sound basis for simulating fine-scale movement and for investigating factors that influence it.

Systematic literature review of determinants of sedentary behaviour in older adults: a DEDIPAC study

Background

Older adults are the most sedentary segment of society and high sedentary time is associated with poor health and wellbeing outcomes in this population. Identifying determinants of sedentary behaviour is a necessary step to develop interventions to reduce sedentary time.

Methods

A systematic literature review was conducted to identify factors associated with sedentary behaviour in older adults. Pubmed, Embase, CINAHL, PsycINFO and Web of Science were searched for articles published between 2000 and May 2014. The search strategy was based on four key elements: (a) sedentary behaviour and its synonyms; (b) determinants and its synonyms (e.g. correlates, factors); (c) types of sedentary behaviour (e.g. TV viewing, sitting, gaming) and (d) types of determinants (e.g. environmental, behavioural). Articles were included in the review if specific information about sedentary behaviour in older adults was reported. Studies on samples identified by disease were excluded. Study quality was rated by means of QUALSYST. The full review protocol is available from PROSPERO (PROSPERO 2014: CRD42014009823). The analysis was guided by the socio-ecological model framework.

Results

Twenty-two original studies were identified out of 4472 returned by the systematic search. These included 19 cross-sectional, 2 longitudinal and 1 qualitative studies, all published after 2011. Half of the studies were European. The study quality was generally high with a median of 82 % (IQR 69–96 %) using Qualsyst tool. Personal factors were the most frequently investigated with consistent positive association for age, negative for retirement, obesity and health status. Only four studies considered environmental determinants suggesting possible association with mode of transport, type of housing, cultural opportunities and neighbourhood safety and availability of places to rest. Only two studies investigated mediating factors. Very limited information was available on contexts and sub-domains of sedentary behaviours.

Conclusion

Few studies have investigated determinants of sedentary behaviour in older adults and these have to date mostly focussed on personal factors, and qualitative studies were mostly lacking. More longitudinal studies are needed as well as inclusion of a broader range of personal and contextual potential determinants towards a systems-based approach, and future studies should be more informed by qualitative work.

Electronic supplementary material

The online version of this article (doi:10.1186/s12966-015-0292-3) contains supplementary material, which is available to authorized users.

The relevance of commuter and work/school exposure in an epidemiological study on traffic-related air pollution

Exposure during transport and at non-residential locations is ignored in most epidemiological studies of traffic-related air pollution. We investigated the impact of separately estimating NO2 long-term outdoor exposures at home, work/school, and while commuting on the association between this marker of exposure and potential health outcomes. We used spatially and temporally resolved commuter route data and model-based NO2 estimates of a population sample in Basel, Switzerland, to assign individual NO2-exposure estimates of increasing complexity, namely (1) home outdoor concentration; (2) time-weighted home and work/school concentrations; and (3) time-weighted concentration incorporating home, work/school and commute. On the basis of their covariance structure, we estimated the expectable relative differences in the regression slopes between a quantitative health outcome and our measures of individual NO2 exposure using a standard measurement error model. The traditional use of home outdoor NO2 alone indicated a 12% (95% CI: 11-14%) underestimation of related health effects as compared with integrating both home and work/school outdoor concentrations. Mean contribution of commuting to total weekly exposure was small (3.2%; range 0.1-13.5%). Thus, ignoring commute in the total population may not significantly underestimate health effects as compared with the model combining home and work/school. For individuals commuting between Basel-City and Basel-Country, ignoring commute may produce, however, a significant attenuation bias of 4% (95% CI: 4-5%). Our results illustrate the importance of including work/school locations in assessments of long-term exposures to traffic-related air pollutants such as NO2. Information on individuals' commuting behavior may further improve exposure estimates, especially for subjects having lengthy commutes along major transportation routes.

Urban happiness: context-sensitive study of the social sustainability of urban settings

Previous studies have reported multifaceted, controversial social outcomes of densely built urban settings. Social sustainability of urban environments have rarely been studied in a context-sensitive manner, identifying the specific ways urban structural characteristics contribute to the behavioural, experiential and well-being outcomes. In this study, an online public participation geographic information system (PPGIS) methodology allowed the place-based study of urban and suburban contexts in the metropolitan region of Helsinki, Finland. Respondents ( N = 3119) located their meaningful places and reported the experiential and well-being outcomes. GIS-based measures of urban structures were calculated within a 500m buffer around their homes. Structural equation modeling was used to assess the contextual variation and the mediational role accessibility and perceived environmental quality play in linking urban structural characteristics with well-being outcomes. Our findings indicated that although increasing urban density was associated with shorter distances to everyday services in both urban and suburban settings, the experiential and well-being outcomes varied. In the urban context, easy access to services contributed to higher perceived environmental quality and positive well-being outcomes, whereas in the suburban setting, the closeness of services decreased the experiential and well-being outcomes. Perceived environmental quality was strongly associated with well-being in both contexts. We concluded that densely built urban neighborhoods can also support social sustainability, but the processes vary between suburban and urban settings. A challenge remains for urban planners on how to improve accessibility and related positive experiential outcomes in suburban contexts.

A framework for using GPS data in physical activity and sedentary behavior studies

Global Positioning Systems (GPS) are applied increasingly in activity studies, yet significant theoretical and methodological challenges remain. This article presents a framework for integrating GPS data with other technologies to create dynamic representations of behaviors in context. Using more accurate and sensitive measures to link behavior and environmental exposures allows for new research questions and methods to be developed.

Changes in mode of travel to work: a natural experimental study of new transport infrastructure

BACKGROUND

New transport infrastructure may promote a shift towards active travel, thereby improving population health. The purpose of this study was to determine the effect of a major transport infrastructure project on commuters' mode of travel, trip frequency and distance travelled to work.

METHODS

Quasi-experimental analysis nested within a cohort study of 470 adults working in Cambridge, UK. The intervention consisted of the opening of a guided busway with a path for walking and cycling in 2011. Exposure to the intervention was defined as the negative of the square root of the shortest distance from home to busway. The outcome measures were changes in commute mode share and number of commute trips - both based on a seven-day travel-to-work record collected before (2009) and after (2012) the intervention - and change in objective commute distance. The mode share outcomes were changes in the proportions of trips (i) involving any active travel, (ii) involving any public transport, and (iii) made entirely by car. Separate multinomial regression models were estimated adjusting for commute and sociodemographic characteristics, residential settlement size and life events.

RESULTS

Proximity to the busway predicted an increased likelihood of a large (>30 %) increase in the share of commute trips involving any active travel (relative risk ratio [RRR] 1.80, 95 % CI 1.27, 2.55) and a large decrease in the share of trips made entirely by car (RRR 2.09, 95 % CI 1.35, 3.21), as well as a lower likelihood of a small (<30 %) reduction in the share of trips involving any active travel (RRR 0.47, 95 % CI 0.28, 0.81). It was not associated with changes in the share of commute trips involving any public transport, the number of commute trips, or commute distance.

CONCLUSIONS

The new infrastructure promoted an increase in the share of commuting trips involving active travel and a decrease in the share made entirely by car. Further analysis will show the extent to which the changes in commute mode share were translated into an increase in time spent in active commuting and consequent health gain.

The role of the local retail food environment in fruit, vegetable and sugar-sweetened beverage consumption in Brazil

Objective

To examine the relationship between the local retail food environment and consumption of fruits and vegetables (FV) and sugar-sweetened beverages (SSB) in São Paulo, Brazil, as well as the moderation effects of income in the studied relationships.

Design

Cross-sectional study design that drew upon neighbourhood- and individual-level data. For each participant, community (density and proximity) and community food environment (availability, variety, quality and price) measures of FV and SSB were assessed in retail food stores and specialized fresh produce markets within 1·6 km of their homes. Poisson generalized estimating equations (GEE) were used to model the associations of food consumption with food environment measures, adjusted by individual-level characteristics.

Setting

São Paulo, Brazil.

Subjects

Adults (n 1842) residing in the same census tracts (n 52) in São Paulo, Brazil as those where the neighbourhood-level measures were taken.

Results

FV availability in neighbourhoods was associated with regular FV consumption (≥5 times/week; prevalence ratio=1·41; 95 % CI 1·19, 1·67). Regular FV consumption prevalence was significantly lower among lower-income individuals living in neighbourhoods with fewer supermarkets and fresh produce markets (P-interaction <0·05). A greater variety of SSB was associated with a 15 % increase in regular SSB consumption (≥5 times/week) prevalence, after adjustment for confounding variables.

Conclusions

Our findings suggest that the local retail food environment is associated with FV and SSB consumption in a Brazilian urban sample.

From the concrete to the intangible: understanding the diverse experiences and impacts of new transport infrastructure

BACKGROUND

Changes to the environment that support active travel have the potential to increase population physical activity. The Cambridgeshire Guided Busway is an example of such an intervention that provides new traffic-free infrastructure for walking, cycling and public transport. This qualitative investigation explored the diverse experiences of new transport infrastructure and its impacts on active travel behaviours.

METHODS

Thirty-eight adult participants from the Commuting and Health in Cambridge natural experimental study were purposively selected according to their demographic and travel behaviour change characteristics and invited to participate in semi-structured interviews between February and June 2013. A mixed-method, following-a-thread approach was used to construct two contrasting vignettes (stories) to which the participants were asked to respond as part of the interviews. Inductive thematic qualitative analysis of the interview data was performed with the aid of QSR NVivo8.

RESULTS

Perceptions of the busway's attributes were important in shaping responses to it. Some participants rarely considered the new transport infrastructure or described it as unappealing because of its inaccessibility or inconvenient routing. Others located more conveniently for access points experienced the new infrastructure as an attractive travel option. Likewise, the guided buses and adjacent path presented ambiguous spaces which were received in different ways, depending on travel preferences. While new features such as on board internet access or off-road cycling were appreciated, shortcomings such as overcrowded buses or a lack of path lighting were barriers to use. The process of adapting to the environmental change was discussed in terms of planning and trialling new behaviours. The establishment of the busway in commuting patterns appeared to be influenced by whether the anticipated benefits of change were realised.

CONCLUSIONS

This study examined the diverse responses to an environmental intervention that may help to explain small or conflicting aggregate effects in quantitative outcome evaluation studies. Place and space features, including accessibility, convenience, pleasantness and safety relative to the alternative options were important for the acceptance of the busway. Our findings show how environmental change supporting active travel and public transport can encourage behaviour change for some people in certain circumstances.

Combined measure of neighborhood food and physical activity environments and weight-related outcomes: The CARDIA study

Engagement in healthy lifestyle behaviors likely reflects access to a diverse and synergistic set of food and physical activity resources, yet most research examines discrete characteristics. We characterized neighborhoods with respect to their composition of features, and quantified associations with diet, physical activity (PA), body mass index (BMI), and insulin resistance (IR) in a longitudinal biracial cohort (n=4143; aged 25-37; 1992-2006). We used latent class analysis to derive population-density-specific ( Collapse

Key Words

• Diet
• Insulin resistance
• Neighborhood
• Obesity
• Physical activity

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MESH Headings

• Adult
• Body Mass Index
• Diet
• Environment
• Exercise
• Female
• Food Supply
• Health Behavior
• Humans
• Insulin Resistance
• Longitudinal Studies
• Male
• Obesity/epidemiology
• Residence Characteristics
• United States/epidemiology

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Grants

• AG0005 NIA NIH HHS
• P30 DK079626 NIDDK NIH HHS
• HHSN268201300025C NHLBI NIH HHS
• P30DK56350 NIDDK NIH HHS
• HHSN268201300027C NHLBI NIH HHS
• R01 HL114091 NHLBI NIH HHS
• R01HL104580 NHLBI NIH HHS
• P30 DK056350 NIDDK NIH HHS
• K12 HD043488 NICHD NIH HHS
• R01 HL104580 NHLBI NIH HHS
• HHSN268201300026C NHLBI NIH HHS
• P30 ES010126 NIEHS NIH HHS
• HHSN268200900041C NHLBI NIH HHS
• HHSN268201300028C NHLBI NIH HHS
• R24 HD050924 NICHD NIH HHS
• HHSN268201300029C NHLBI NIH HHS
• P30ES010126 NIEHS NIH HHS
• R24HD050924 NICHD NIH HHS

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Affiliation(s)

Katie A Meyer Department of Nutrition, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
Janne Boone-Heinonen Public Health and Preventive Medicine, Oregon Health and Science University, Portland, OR, United States
Kiyah J Duffey Department of Human Nutrition, Foods, and Exercise, Virginia Polytechnic Institute, Blacksburg, VA, United States
Daniel A Rodriguez Department of City and Regional Planning, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
Catarina I Kiefe Quantitative Health Sciences, University of Massachusetts Medical School, Worcester, MA, United States
Cora E Lewis Division of Preventive Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
Penny Gordon-Larsen Department of Nutrition, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States; Carolina Population Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States

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Anonymisation of address coordinates for microlevel analyses of the built environment: a simulation study

BACKGROUND

Data privacy is a major concern in spatial epidemiology because exact residential locations or parts of participants' addresses such as street or zip codes are used to perform geospatial analyses. To overcome this concern, different levels of aggregation such as census districts or zip code areas are mainly used, though any spatial aggregation leads to a loss of spatial variability. For the assessment of urban opportunities for physical activity that was conducted in the IDEFICS (Identification and prevention of dietary- and lifestyle-induced health effects in children and infants) study, macrolevel analyses were performed, but the use of exact residential addresses for micro-level analyses was not permitted by the responsible office for data protection. We therefore implemented a spatial blurring to anonymise address coordinates depending on the underlying population density.

METHODS

We added a standard Gaussian distributed error to individual address coordinates with the variance σ² depending on the population density and on the chosen k-anonymity. 1000 random point locations were generated and repeatedly blurred 100 times to obtain anonymised locations. For each location 1 km network-dependent neighbourhoods were used to calculate walkability indices. Indices of blurred locations were compared to indices based on their sampling origins to determine the effect of spatial blurring on the assessment of the built environment.

RESULTS

Spatial blurring decreased with increasing population density. Similarly, mean differences in walkability indices also decreased with increasing population density. In particular for densely-populated areas with at least 1500 residents per km², differences between blurred locations and their sampling origins were small and did not affect the assessment of the built environment after spatial blurring.

CONCLUSIONS

This approach allowed the investigation of the built environment at a microlevel using individual network-dependent neighbourhoods, while ensuring data protection requirements. Minor influence of spatial blurring on the assessment of walkability was found that slightly affected the assessment of the built environment in sparsely-populated areas.

A novel assessment of adolescent mobility: a pilot study

Background

The accurate measurement of daily mobility and travel to destinations beyond the residential neighbourhood has been identified as an important but almost systematically overlooked factor when investigating the relationship between exposure to the built environment and physical activity. The recent development of VERITAS – a web-based application nested within a computer-assisted personal interview – allows researchers to assess daily mobility, travel to regular destinations, and perceived neighbourhood boundaries using interactive mapping technology. The aims of this pilot study were to (1) demonstrate the feasibility and functionality of using VERITAS in an adolescent sample, and (2) compare urban form characteristics and geometric features of the perceived neighbourhood with traditional neighbourhood delimitations.

Methods

Data were collected and analysed for twenty-eight participants (14 male, 15.9 ± 1.48 years) in 2013. Participants underwent anthropometric assessment before completing a custom-designed VERITAS protocol under the supervision of trained interview technicians. Regularly visited destinations, school travel routes, transportation modes, travel companions, and perceived neighbourhood boundaries were assessed. Data were imported into ArcGIS and street network distances between the home and each geolocated destination were generated. Convex hull activity spaces were derived from destinations. Urban form variables and geometric characteristics were compared between the perceived neighbourhood, existing meshblocks, 1 mile Euclidean buffers, and 1 km network buffers.

Results

In total, 529 destinations were geolocated, 58% of which were outside the perceived neighbourhood boundary. Active travel was inversely associated with distance to destinations (r = −.43, p < .05) and traveling with adults (r = −.68, p < .01). Urban form and geometric characteristics of the perceived neighbourhood were different from those in other neighbourhood delimitations.

Conclusions

This study demonstrates the feasibility of using VERITAS to assess mobility within adolescent populations. Our results also illustrate the potential novelty and use of user-defined spaces, and highlight the limitations of relying on restricted definitions of place (i.e., administrative or residential-focused neighbourhoods) when assessing environmental exposure.

Associations between BMI and home, school and route environmental exposures estimated using GPS and GIS: do we see evidence of selective daily mobility bias in children?

Background

This study examined whether objective measures of food, physical activity and built environment exposures, in home and non-home settings, contribute to children’s body weight. Further, comparing GPS and GIS measures of environmental exposures along routes to and from school, we tested for evidence of selective daily mobility bias when using GPS data.

Methods

This study is a cross-sectional analysis, using objective assessments of body weight in relation to multiple environmental exposures. Data presented are from a sample of 94 school-aged children, aged 5–11 years. Children’s heights and weights were measured by trained researchers, and used to calculate BMI z-scores. Participants wore a GPS device for one full week. Environmental exposures were estimated within home and school neighbourhoods, and along GIS (modelled) and GPS (actual) routes from home to school. We directly compared associations between BMI and GIS-modelled versus GPS-derived environmental exposures. The study was conducted in Mebane and Mount Airy, North Carolina, USA, in 2011.

Results

In adjusted regression models, greater school walkability was associated with significantly lower mean BMI. Greater home walkability was associated with increased BMI, as was greater school access to green space. Adjusted associations between BMI and route exposure characteristics were null. The use of GPS-actual route exposures did not appear to confound associations between environmental exposures and BMI in this sample.

Conclusions

This study found few associations between environmental exposures in home, school and commuting domains and body weight in children. However, walkability of the school neighbourhood may be important. Of the other significant associations observed, some were in unexpected directions. Importantly, we found no evidence of selective daily mobility bias in this sample, although our study design is in need of replication in a free-living adult sample.

Electronic supplementary material

The online version of this article (doi:10.1186/1476-072X-14-8) contains supplementary material, which is available to authorized users.

Generating GPS activity spaces that shed light upon the mobility habits of older adults: a descriptive analysis

Background

Measuring mobility is critical for understanding neighborhood influences on older adults’ health and functioning. Global Positioning Systems (GPS) may represent an important opportunity to measure, describe, and compare mobility patterns in older adults.

Methods

We generated three types of activity spaces (Standard Deviation Ellipse, Minimum Convex Polygon, Daily Path Area) using GPS data from 95 older adults in Vancouver, Canada. Calculated activity space areas and compactness were compared across sociodemographic and resource characteristics.

Results

Area measures derived from the three different approaches to developing activity spaces were highly correlated. Participants who were younger, lived in less walkable neighborhoods, had a valid driver’s license, had access to a vehicle, or had physical support to go outside of their homes had larger activity spaces. Mobility space compactness measures also differed by sociodemographic and resource characteristics.

Conclusions

This research extends the literature by demonstrating that GPS tracking can be used as a valuable tool to better understand the geographic mobility patterns of older adults. This study informs potential ways to maintain older adult independence by identifying factors that influence geographic mobility.

Electronic supplementary material

The online version of this article (doi:10.1186/1476-072X-13-51) contains supplementary material, which is available to authorized users.

Assessing patterns of spatial behavior in health studies: their socio-demographic determinants and associations with transportation modes (the RECORD Cohort Study)

Prior epidemiological studies have mainly focused on local residential neighborhoods to assess environmental exposures. However, individual spatial behavior may modify residential neighborhood influences, with weaker health effects expected for mobile populations. By examining individual patterns of daily mobility and associated socio-demographic profiles and transportation modes, this article seeks to develop innovative methods to account for daily mobility in health studies. We used data from the RECORD Cohort Study collected in 2011-2012 in the Paris metropolitan area, France. A sample of 2062 individuals was investigated. Participants' perceived residential neighborhood boundaries and regular activity locations were geocoded using the VERITAS application. Twenty-four indicators were created to qualify individual space-time patterns, using spatial analysis methods and a geographic information system. Three domains of indicators were considered: lifestyle indicators, indicators related to the geometry of the activity space, and indicators related to the importance of the residential neighborhood in the overall activity space. Principal component analysis was used to identify main dimensions of spatial behavior. Multilevel linear regression was used to determine which individual characteristics were associated with each spatial behavior dimension. The factor analysis generated five dimensions of spatial behavior: importance of the residential neighborhood in the activity space, volume of activities, and size, eccentricity, and specialization of the activity space. Age, socioeconomic status, and location of the household in the region were the main predictors of daily mobility patterns. Activity spaces of small sizes centered on the residential neighborhood and implying a large volume of activities were associated with walking and/or biking as a transportation mode. Examination of patterns of spatial behavior by individual socio-demographic characteristics and in relation to transportation modes is useful to identify populations with specific mobility/accessibility needs and has implications for investigating transportation-related physical activity and assessing environmental exposures and their effects on health.

Chronic air pollution and social deprivation as modifiers of the association between high temperature and daily mortality

BACKGROUND

Heat and air pollution are both associated with increases in mortality. However, the interactive effect of temperature and air pollution on mortality remains unsettled. Similarly, the relationship between air pollution, air temperature, and social deprivation has never been explored.

METHODS

We used daily mortality data from 2004 to 2009, daily mean temperature variables and relative humidity, for Paris, France. Estimates of chronic exposure to air pollution and social deprivation at a small spatial scale were calculated and split into three strata. We developed a stratified Poisson regression models to assess daily temperature and mortality associations, and tested the heterogeneity of the regression coefficients of the different strata. Deaths due to ambient temperature were calculated from attributable fractions and mortality rates were estimated.

RESULTS

We found that chronic air pollution exposure and social deprivation are effect modifiers of the association between daily temperature and mortality. We found a potential interactive effect between social deprivation and chronic exposure with regards to air pollution in the mortality-temperature relationship.

CONCLUSION

Our results may have implications in considering chronically polluted areas as vulnerable in heat action plans and in the long-term measures to reduce the burden of heat stress especially in the context of climate change.

Developing suitable buffers to capture transport cycling behavior

The association between neighborhood built environment and cycling has received considerable attention in health literature over the last two decades, but different neighborhood definitions have been used and it is unclear which one is most appropriate. Administrative or fixed residential spatial units (e.g., home-buffer-based neighborhoods) are not necessarily representative for environmental exposure. An increased understanding of appropriate neighborhoods is needed. GPS cycling tracks from 78 participants for 7 days form the basis for the development and testing of different neighborhood buffers for transport cycling. The percentage of GPS points per square meter was used as indicator of the effectiveness of a series of different buffer types, including home-based network buffers, shortest route to city center buffers, and city center-directed ellipse-shaped buffers. The results show that GPS tracks can help us understand where people go and stay during the day, which can help us link built environment with cycling. Analysis showed that the further people live from the city center, the more elongated are their GPS tracks, and the better an ellipse-shaped directional buffer captured transport cycling behavior. In conclusion, we argue that in order to be able to link built environment factors with different forms of physical activity, we must study the most likely area people use. In this particular study, to capture transport cycling, with its relatively large radius of action, city center-directed ellipse-shaped buffers yielded better results than traditional home-based network buffer types. The ellipse-shaped buffer types could therefore be considered an alternative to more traditional buffers or administrative units in future studies of transport cycling behavior.

Characteristics of residential areas and transportational walking among frail and non-frail Dutch elderly: does the size of the area matter?

Background

A residential area supportive for walking may facilitate elderly to live longer independently. However, current evidence on area characteristics potentially important for walking among older persons is mixed. This study hypothesized that the importance of area characteristics for transportational walking depends on the size of the area characteristics measured, and older person’s frailty level.

Methods

The study population consisted of 408 Dutch community-dwelling persons aged 65 years and older participating in the Elderly And their Neighborhood (ELANE) study in 2011–2012. Characteristics (aesthetics, functional features, safety, and destinations) of areas surrounding participants’ residences ranging from a buffer of 400 meters up to 1600 meters (based on walking path networks) were linked with self-reported transportational walking using linear regression analyses. In addition, interaction effects between frailty level and area characteristics were tested.

Results

An increase in functional features (e.g. presence of sidewalks and benches) within a 400 meter buffer, in aesthetics (e.g. absence of litter and graffiti) within 800 and 1200 meter buffers, and an increase of one destination per buffer of 400 and 800 meters were associated with more transportational walking, up to 2.89 minutes per two weeks (CI 1.07-7.32; p < 0.05). No differences were found between frail and non-frail elderly.

Conclusions

Better functional and aesthetic features, and more destinations in the residential area of community-dwelling older persons were associated with more transportational walking. The importance of area characteristics for transportational walking differs by area size, but not by frailty level. Neighbourhood improvements may increase transportational walking among older persons, thereby contributing to living longer independently.

How many walking and cycling trips made by elderly are beyond commonly used buffer sizes: results from a GPS study

In choosing appropriate buffer sizes to study environmental influences on physical activity, studies are hampered by insufficient insight into the distance elderly travel actively. This study aims at getting insight into the number of trips walked and cycled within various buffer sizes using GPS measures. Data were obtained from the Elderly And their Neighborhood study (Spijkenisse, the Netherlands (2011-2012)). Trip length and mode of transport were derived from the GPS data (N=120; total number of trips=337). Distance decay functions were fitted to estimate the percentage of trips to grocery stores within commonly used buffer sizes. Fifty percent of the trips walked had a distance of at least 729m; for trips cycled this was 1665m. Elderly aged under 75 years and those with functional limitations walked and cycled shorter distances than those over 75 years and those without functional limitations. Males cycled shorter distances than females. Distance decay functions may aid the selection of appropriate buffer sizes, which may be tailored to individual characteristics.

Detecting activity locations from raw GPS data: a novel kernel-based algorithm

Background

Health studies and mHealth applications are increasingly resorting to tracking technologies such as Global Positioning Systems (GPS) to study the relation between mobility, exposures, and health. GPS tracking generates large sets of geographic data that need to be transformed to be useful for health research. This paper proposes a method to test the performance of activity place detection algorithms, and compares the performance of a novel kernel-based algorithm with a more traditional time-distance cluster detection method.

Methods

A set of 750 artificial GPS tracks containing three stops each were generated, with various levels of noise.. A total of 9,000 tracks were processed to measure the algorithms’ capacity to detect stop locations and estimate stop durations, with varying GPS noise and algorithm parameters.

Results

The proposed kernel-based algorithm outperformed the traditional algorithm on most criteria associated to activity place detection, and offered a stronger resilience to GPS noise, managing to detect up to 92.3% of actual stops, and estimating stop duration within 5% error margins at all tested noise levels.

Conclusions

Capacity to detect activity locations is an important feature in a context of increasing use of GPS devices in health and place research. While further testing with real-life tracks is recommended, testing algorithms’ performance with artificial track sets for which characteristics are controlled is useful. The proposed novel algorithm outperformed the traditional algorithm under these conditions.