Julie Vallée

Incidence of Stroke and Socioeconomic Neighborhood Characteristics: An Ecological Analysis of Dijon Stroke Registry

Background and Purpose— Studies have shown higher stroke incidence in areas with higher levels of deprivation. We aimed to determine the pattern of association between various area socioeconomic status (SES) indicators and stroke incidence in specific sex and age groups. Methods— Data are from the Dijon stroke registry for the period 1995 to 2003. The analyses included 1255 cases aged older than 40 (median age, 76.8). Poisson regression was used to model stroke incidence according to the SES level of 61 small areas. Results— Among women, stroke incidence was higher in neighborhoods with large income inequality (incidence rate ratio, 1.34; P=0.003), higher proportions of unemployed (1.24; P=0.02), of non-French nationals (1.21, P=0.02), and of rented housing (1.31; P=0.03). Areas with a higher proportion of people aged older than 60 were associated with lower stroke incidence (incidence rate ratio, 0.72; P=0.01). Analysis by specific age-groups showed stronger effects among the 60- to 74-year-olds. Among men, no associations between SES and stroke incidence were identified overall but analysis by age groups showed significant effect among the 40- to 59-year-olds. In this age group, incidence rate ratios were 1.47 for unemployment (P=0.01), 1.86 for no car ownership (P=0.02), and 1.56 for income inequality (P=0.01). Among stroke cases, no trend in vascular risk factors prevalence according to area SES was identified. Conclusions— Variations of stroke incidence were more marked for the SES indicators of wealth and of income inequality. They were apparent at an earlier age in men and showed a stronger gradient among women.

Spatial distribution and risk factors of dengue and Japanese encephalitis virus infection in urban settings: the case of Vientiane, Lao PDR

Objectives  To evaluate the prevalence of flavivirus infection in Vientiane city (Lao PDR), to describe the spatial distribution of infection within this city, and to explore the link between flavivirus seroprevalence and urbanization levels of residential neighbourhoods.

The ‘constant size neighbourhood trap’ in accessibility and health studies

In literature on neighbourhood effects and resources accessibility, the number of neighbourhood resources to which residents may have access are often estimated from spatial units whose constant size fails to account for unique ways residents experience their neighbourhoods. To investigate this ‘constant size neighbourhood trap’, we compared numbers of healthcare resources included in Constant Size Buffers (CSBs) and in Perceived Neighbourhood Polygons (PNPs) from cognitive neighbourhood data collected among 653 residents of the Paris metropolitan area. We observed that residents of deprived and peripheral areas had smaller PNPs than their counterparts. Studying residents assessments of the quantity of neighbourhood practitioners, we then assessed the validity of using PNPs rather than CSBs to estimate number of neighbourhood resources. Lastly, resource inequalities across the Paris metropolitan area were found to be far wider when considering PNPs rather than CSBs. Using constant neighbourhood delineation can lead to inaccurately measured individual accessibility to neighbourhood resources and to downplay the extent of inequalities in urban resources.

Contrasting Spatial Distribution and Risk Factors for Past Infection with Scrub Typhus and Murine Typhus in Vientiane City, Lao PDR

Background The aetiological diagnostic of fevers in Laos remains difficult due to limited laboratory diagnostic facilities. However, it has recently become apparent that both scrub and murine typhus are common causes of previous undiagnosed fever. Epidemiological data suggests that scrub typhus would be more common in rural areas and murine typhus in urban areas, but there is very little recent information on factors involved in scrub and murine typhus transmission, especially where they are sympatric - as is the case in Vientiane, the capital of the Lao PDR. Methodology and Principal Findings We therefore determined the frequency of IgG seropositivity against scrub typhus (Orientia tsutsugamushi) and murine typhus (Rickettsia typhi), as indices of prior exposure to these pathogens, in randomly selected adults in urban and peri-urban Vientiane City (n = 2,002, ≥35 years). Anti-scrub and murine typhus IgG were detected by ELISA assays using filter paper elutes. We validated the accuracy of ELISA of these elutes against ELISA using serum samples. The overall prevalence of scrub and murine typhus IgG antibodies was 20.3% and 20.6%, respectively. Scrub typhus seropositivity was significantly higher among adults living in the periphery (28.4%) than in the central zone (13.1%) of Vientiane. In contrast, seroprevalence of murine typhus IgG antibodies was significantly higher in the central zone (30.8%) as compared to the periphery (14.4%). In multivariate analysis, adults with a longer residence in Vientiane were at significant greater risk of past infection with murine typhus and at lower risk for scrub typhus. Those with no education, living on low incomes, living on plots of land with poor sanitary conditions, living in large households, and farmers were at higher risk of scrub typhus and those living in neighborhoods with high building density and close to markets were at greater risk for murine typhus and at lower risk of scrub typhus past infection. Conclusions This study underscores the intense circulation of both scrub and murine typhus in Vientiane city and underlines difference in spatial distribution and risk factors involved in the transmission of these diseases.

Neighborhood environments, mobility, and health: Towards a new generation of studies in environmental health research

While public policies seek to promote active transportation, there is a lack of information on the social and environmental factors associated with the adoption of active transportation modes. Moreover, despite the consensus on the importance of identifying obesogenic environmental factors, most published studies only take into account residential neighborhoods in the definition of exposures. There are at least three major reasons for incorporating daily mobility in public health research: (i) to identify specific population groups, including socially disadvantaged populations, who experience mobility or spatial accessibility deficits; (ii) to study the environmental determinants of transportation habits and investigate the complex relationships between transportation (as a source of physical activity, pollutants, and accidents) and physical activity and health; and (iii) to improve the assessment of spatial accessibility to resources and exposure to environmental hazards by accounting for daily trajectories for a better understanding of their health effects. There is urgent need to develop novel methods to better assess daily mobility. The RECORD Study relies on (i) an electronic survey of regular mobility to assess the chronic exposure to environmental conditions over a relatively long period, and (ii) Global Positioning System tracking to evaluate precisely acute environmental exposures over a much shorter period. The present article argues that future research should combine these two approaches. Gathering scientific evidence on the relationships between the environments, mobility/transportation, and health should allow public health and urban planning decision makers to better take into account the individual and environmental barriers to the adoption of active transportation and to define innovative intervention strategies addressing obesogenic environments to reduce disparities in excess weight.

Inequalities in cervical cancer screening for women with or without a regular consulting in primary care for gynaecological health, in Paris, France.

OBJECTIVES To describe the individual characteristics associated with the absence of cervical smear (CCST); to investigate the role of residential neighbourhood, particularly practitioner density; and to explore changes in individual and contextual determinants after taking regular consulting in primary care for gynaecological health (RCGH) into account. METHODS DATA 1843 adult women from the SIRS survey conducted in 2005 in the Paris metropolitan area. Multilevel logistic regressions analysed factors associated with never-screening. RESULTS 10% of the women had never undergone CCST. Being single, less educated, of foreign origin, with no children, and without health insurance, having never worked, having never undergone a serious health problem and/or having nobody in their circle with cancer were associated with no CCST. Once adjusted on individual characteristics, living in a middle- (OR=1.95; IC=1.05-3.62) or in a lower-class neighbourhood (OR=2.31; IC=1.26-4.25) was associated with increased risks of never-screening, but neighbourhood physician density was not. Interactions were found between socioeconomic status and RCGH. Individual- and neighbourhood-level associations with CCST were different for women with or without an RCGH. CONCLUSION This study analysed individual and contextual inequalities in CCST practice in the Paris metropolitan area. To benefit from an RCGH did not seem to reduce all the social inequalities in CCST practice.

Investigating the effects of medical density on health-seeking behaviours using a multiscale approach to residential and activity spaces: Results from a prospective cohort study in the Paris metropolitan area, France

BackgroundWhen measuring neighbourhood effects on health, it is both incorrect to treat individuals as if they were static and tied to their residential neighbourhood and to consider neighbourhoods rigid places whose geographical scales can be delineated a priori. We propose here to investigate the effects of residential medical density on health-seeking behaviours, taking into account the mono/polycentric structure of individual activity space (i.e., the space within which people move in the course of their daily activities) and exploring various neighbourhood units based on administrative delineations and regular grids.MethodsWe used data collected in the SIRS cohort study, which was carried out over a 5-year period (2005–2010) among a representative population living in 50 census blocks in the Paris metropolitan area. In the 662 women who lived in the same census blocks during the follow-up period and who had reported a recent cervical screening at baseline, we studied the association between residential medical density and individual activity space and the incidence of delayed cervical screening (> 3 years) in multilevel logistic regression models after adjustment for potential confounders.ResultsAmong the 662 women studied, there were 94 instances of delayed cervical screening in 2010 (14%). The women who indicated that their activity space was concentrated within their neighbourhood of residence were significantly more at risk for an incident delayed cervical screening. No significant association was found between residential medical density and the incidence of delayed cervical screening. However, we observed a significant interaction between individual activity space and residential medical density. Indeed, women living in neighbourhoods with a low medical density had a significantly higher risk of delayed screening, but only if they reported that their daily activities were centred within their neighbourhood of residence. Lastly, a sensitivity analysis exploring various neighbourhood spatial units revealed that the incidence of delayed screening was better modelled when residential medical densities were calculated from a 1400 × 1400 metre grid or from adjacent census blocks.ConclusionThis analysis underscores the view that people and neighbourhoods should be considered interacting entities. Using unsuitable neighbourhood units or neglecting the mono/polycentric structure of activity space would result in downplaying the importance of access to local health resources when addressing inequalities in health-seeking behaviours.

Sampling in health geography: reconciling geographical objectives and probabilistic methods. An example of a health survey in Vientiane (Lao PDR)

BackgroundGeographical objectives and probabilistic methods are difficult to reconcile in a unique health survey. Probabilistic methods focus on individuals to provide estimates of a variables prevalence with a certain precision, while geographical approaches emphasise the selection of specific areas to study interactions between spatial characteristics and health outcomes. A sample selected from a small number of specific areas creates statistical challenges: the observations are not independent at the local level, and this results in poor statistical validity at the global level. Therefore, it is difficult to construct a sample that is appropriate for both geographical and probability methods.MethodsWe used a two-stage selection procedure with a first non-random stage of selection of clusters. Instead of randomly selecting clusters, we deliberately chose a group of clusters, which as a whole would contain all the variation in health measures in the population. As there was no health information available before the survey, we selected a priori determinants that can influence the spatial homogeneity of the health characteristics. This method yields a distribution of variables in the sample that closely resembles that in the overall population, something that cannot be guaranteed with randomly-selected clusters, especially if the number of selected clusters is small. In this way, we were able to survey specific areas while minimising design effects and maximising statistical precision.ApplicationWe applied this strategy in a health survey carried out in Vientiane, Lao Peoples Democratic Republic. We selected well-known health determinants with unequal spatial distribution within the city: nationality and literacy. We deliberately selected a combination of clusters whose distribution of nationality and literacy is similar to the distribution in the general population.ConclusionThis paper describes the conceptual reasoning behind the construction of the survey sample and shows that it can be advantageous to choose clusters using reasoned hypotheses, based on both probability and geographical approaches, in contrast to a conventional, random cluster selection strategy.

The added value of accounting for activity space when examining the association between tobacco retailer availability and smoking among young adults

Background Despite a declining prevalence in many countries, smoking rates remain consistently high among young adults. Targeting contextual influences on smoking, such as the availability of tobacco retailers, is one promising avenue of intervention. Most studies have focused on residential or school neighbourhoods, without accounting for other settings where individuals spend time, that is, their activity space. We investigated the association between tobacco retailer availability in the residential neighbourhood and in the activity space, and smoking status. Methods Cross-sectional baseline data from 1994 young adults (aged 18–25) participating in the Interdisciplinary Study of Inequalities in Smoking (Montreal, Canada, 2011–2012) were analysed. Residential and activity locations served to derive two measures of tobacco retailer availability: counts within 500 m buffers and proximity to the nearest retailer. Prevalence ratios for the association between each tobacco retailer measure and smoking status were estimated using log-binomial regression. Results Participants encountering high numbers of tobacco retailers in their residential neighbourhood, and both medium and high retailer counts in their activity space, were more likely to smoke compared to those exposed to fewer retailers. While residential proximity was not associated with smoking, we found 36% and 42% higher smoking prevalence among participants conducting activities within medium and high proximity to tobacco retailers compared to those conducting activities further from such outlets. Conclusions This study adds to the sparse literature on contextual correlates of smoking among young adults, and illustrates the added value of considering individuals’ activity space in contextual studies of smoking.

Understanding the role of contrasting urban contexts in healthy aging: an international cohort study using wearable sensor devices (the CURHA study protocol)

BackgroundGiven the challenges of aging populations, calls have been issued for more sustainable urban re-development and implementation of local solutions to address global environmental and healthy aging issues. However, few studies have considered older adults’ daily mobility to better understand how local built and social environments may contribute to healthy aging. Meanwhile, wearable sensors and interactive map-based applications offer novel means for gathering information on people’s mobility, levels of physical activity, or social network structure. Combining such data with classical questionnaires on well-being, physical activity, perceived environments and qualitative assessment of experience of places opens new opportunities to assess the complex interplay between individuals and environments. In line with current gaps and novel analytical capabilities, this research proposes an international research agenda to collect and analyse detailed data on daily mobility, social networks and health outcomes among older adults using interactive web-based questionnaires and wearable sensors.Methods/DesignOur study resorts to a battery of innovative data collection methods including use of a novel multisensor device for collection of location and physical activity, interactive map-based questionnaires on regular destinations and social networks, and qualitative assessment of experience of places. This rich data will allow advanced quantitative and qualitative analyses in the aim to disentangle the complex people-environment interactions linking urban local contexts to healthy aging, with a focus on active living, social networks and participation, and well-being.DiscussionThis project will generate evidence about what characteristics of urban environments relate to active mobility, social participation, and well-being, three important dimensions of healthy aging. It also sets the basis for an international research agenda on built environment and healthy aging based on a shared and comprehensive data collection protocol.