The association between sidewalk length and walking for different purposes in established neighborhoods.

BACKGROUND: Walking in neighborhood environments is undertaken for different purposes including for transportation and leisure. We examined whether sidewalk availability was associated with participation in, and minutes of neighborhood-based walking for transportation (NWT) and recreation (NWR) after controlling for neighborhood self-selection. METHOD: Baseline survey data from respondents (n = 1813) who participated in the RESIDential Environment (RESIDE) project (Perth, Western Australia) were used. Respondents were recruited based on their plans to move to another neighborhood in the following year. Usual weekly neighborhood-based walking, residential preferences, walking attitudes, and demographics were measured. Characteristics of the respondent's baseline neighborhood were measured including transportation-related walkability and sidewalk length. A Heckman two-stage modeling approach (multivariate Probit regression for walking participation, followed by a sample selection-bias corrected OLS regression for walking minutes) estimated the relative contribution of sidewalk length to NWT and NWR. RESULTS: After adjustment, neighborhood sidewalk length and walkability were positively associated with a 2.97 and 2.16 percentage point increase in the probability of NWT participation, respectively. For each 10 km increase in sidewalk length, NWT increased by 5.38 min/wk and overall neighborhood-based walking increased by 5.26 min/wk. Neighborhood walkability was not associated with NWT or NWR minutes. Moreover, sidewalk length was not associated with NWR minutes. CONCLUSIONS: Sidewalk availability in established neighborhoods may be differentially associated with walking for different purposes. Our findings suggest that large investments in sidewalk construction alone would yield small increases in walking.

How important is the land use mix measure in understanding walking behaviour? Results from the RESIDE study.

BACKGROUND: Understanding the relationship between urban design and physical activity is a high priority. Different representations of land use diversity may impact the association between neighbourhood design and specific walking behaviours. This study examined different entropy based computations of land use mix (LUM) used in the development of walkability indices (WIs) and their association with walking behaviour. METHODS: Participants in the RESIDential Environments project (RESIDE) self-reported mins/week of recreational, transport and total walking using the Neighbourhood Physical Activity Questionnaire (n = 1798). Land use categories were incrementally added to test five different LUM models to identify the strongest associations with recreational, transport and total walking. Logistic regression was used to analyse associations between WIs and walking behaviour using three cut points: any (> 0 mins), ≥ 60 mins and ≥ 150 mins walking/week. RESULTS: Participants in high (vs. low) walkable neighbourhoods reported up to almost twice the amount of walking, irrespective of the LUM measure used. However, different computations of LUM were found to be relevant for different types and amounts of walking (i.e., > 0, ≥ 60 or ≥ 150 mins/week). Transport walking (≥ 60 mins/week) had the strongest and most significant association (OR = 2.24; 95% CI:1.58-3.18) with the WI when the LUM included 'residential', 'retail', 'office', 'health, welfare and community', and 'entertainment, culture and recreation'. However, any (> 0 mins/week) recreational walking was more strongly associated with the WI (OR = 1.36; 95% CI:1.04-1.78) when land use categories included 'public open space', 'sporting infrastructure' and 'primary and rural' land uses. The observed associations were generally stronger for ≥ 60 mins/week compared with > 0 mins/week of transport walking and total walking but this relationship was not seen for recreational walking. CONCLUSIONS: Varying the combination of land uses in the LUM calculation of WIs affects the strength of relationships with different types (and amounts) of walking. Future research should examine the relationship between walkability and specific types and different amounts of walking. Our results provide an important first step towards developing a context-specific WI that is associated with recreational walking. Inherent problems with administrative data and the use of entropy formulas for the calculation of LUM highlight the need to explore alternative or complimentary measures of the environment.

Cost-effectiveness implications of GP intervention to promote physical activity: evidence from Perth, Australia.

BACKGROUND: Physical inactivity is a major risk factor for many chronic diseases including diabetes, cardiovascular diseases and some cancers. It is estimated that, in Australia, physical inactivity contributes to 13,500 annual deaths and incurs an annual cost of AU$ 21 billion to the health care system. The cost of physical inactivity to the Western Australian (WA) economy is estimated to be about AU$ 2.1 billion. Increased burden of physical inactivity has motivated health professionals to seek cost effective intervention to promote physical activity. One such strategy is encouraging general practitioners (GPs) to advocate physical activity to the patients who are at high risk of developing chronic diseases associated with physical inactivity. This study intends to investigate the cost-effectiveness of a subsidy program for GP advice to promote physical activity. METHODOLOGY: The percentage of population that could potentially move from insufficiently active to sufficiently active, on GP advice was drawn from the Western Australian (WA) Premier's Physical Activity Taskforce (PATF) survey in 2006. Population impact fractions (PIF) for diseases attributable to physical inactivity together with disability adjusted life years (DALYs) and health care expenditure were used to estimate the net cost of intervention for varying subsidies. Cost-effectiveness of subsidy programs were evaluated in terms of cost per DALY saved at different compliance rates. RESULTS: With a 50% adherence to GP advice, an annual health care cost of AU$ 24 million could be potentially saved to the WA economy. A DALY can be saved at a cost of AU $ 11,000 with a AU$ 25 subsidy at a 50% compliance rate. Cost effectiveness of such a subsidy program decreases at higher subsidy and lower compliance rates. CONCLUSION: Implementing a subsidy for GP advice could potentially reduce the burden of physical inactivity. However, the cost-effectiveness of a subsidy program for GP advice depends on the percentage of population who comply with GP advice.

The influence of socioeconomic and environmental determinants on health and obesity: a West Virginia case study.

A recursive system of ordered self assessed health together with BRFSS data were used to investigate health and obesity in the Appalachian state of West Virginia. Implications of unobserved heterogeneity and endogeneity of lifestyle outcomes on health were investigated. Obesity was found to be an endogenous lifestyle outcome associated with impaired health status. Risk of obesity is found to increase at a decreasing rate with per capita income and age. Intervention measures which stimulate human capital development, diet-disease knowledge and careful land use planning may improve health and obesity outcomes in Appalachia in particular and rural America in general.