Mark Daniel

Association between smoking, insulin resistance and β-cell function in a North-western First Nation

Aims  Aboriginal peoples have a high prevalence of smoking and are at major risk for diabetes. The role of insulin resistance vs. compromised β‐cell function in the link between smoking and glycaemic disease is not clear. This study tested whether relations between insulin resistance and β‐cell function differ between current smokers, former smokers and non‐smokers, and if having diabetes modifies smoking‐related effects.

The effect of adherence on the association between depressive symptoms and mortality among HIV-infected individuals first initiating HAART.

Objective:To determine the impact of depressive symptoms on mortality among HIV/AIDS patients first initiating HAART and the potential role of patient adherence as a confounder and effect modifier in this association. Methods:The study comprised HIV-positive individuals who were first prescribed HAART between August 1996 and June 2002. Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression Scale. Cox proportional hazards models were used to determine the association between depressive symptoms, adherence and all-cause mortality while controlling for several baseline confounding factors. Results:A total of 563 participants met the study inclusion criteria. Of these subjects, 51% had depressive symptoms at baseline and 23% of participants were less than 95% adherent in the first year of follow-up. The overall all-cause mortality rate was 10%. Multivariate analysis showed that individuals with depressive symptoms and adherence < 95% were 5.90 times (95% confidence interval, 2.55–13.68) more likely to die than adherent patients with no depressive symptoms. The estimated median model-based survival probabilities stratified by adherence and depressive symptoms levels ranged from 81% (interquartile range, 72–89%) for depressive symptoms and adherence < 95% to 97% (interquartile range, 94–98%) for no depressive symptoms and adherence ≥ 95%. Conclusion:The results indicate that both depressive symptoms and adherence were associated with shorter survival among individuals with HIV accessing HAART. Given the high prevalence of depressive symptoms in HIV-positive patients and a strong association with adherence, the findings support improvement in the diagnosis and treatment of depression as well as adherence in order to maximize the effectiveness of HAART.

Partnerships and coalitions for community-based research.

Address correspondence to Dr. Green, Office on Smoking and Health, CDC, 4770 Buford Hwy, MS K-50, Atlanta GA 30341-3717; tel. 770-488-5701; fax 770-488-5767; e-mail . WHAT HAVE SEVERAL DECADES OF HEALTH EDUCATION, PROMOTION, and engagement with community and academic partners taught us about community-based research in public health? We know that some lessons derive from specific studies,1,2 others from reviews of international research literature,3,4 and still others from guides that help practitioners apply their apparent lessons.5 This commentary blends the findings of these various studies, reviews, and guides with general principles and guidelines that have emerged from our combined experience and observa tions in academic, foundation, federal, state, and local situations in the United States, Canada, Australia, and other countries. Our comments center on community-based partnerships, coalitions, and infrastructure building, but we emphasize that horizontal commu nity coalitions and partnerships must be based on strong vertical rela tionships between local entities and their state and national counter parts or headquarter organizations. We assume that university-based researchers are often, but not necessarily or always, part of community based partnership. In order to answer our first question, we pose additional questions: Why is some partnering essential to community-based research? How much partnering is needed to facilitate the research, community planning, and execution of programs? What are the principles and components of good community partnerships, and how do they fit with the principles of participatory research and the particular demands of academic-community partnerships? What are some cautions for partnerships that become large coalitions? Finally, what lessons have the large community trials in chronic disease prevention taught us?

Using experienced activity spaces to measure foodscape exposure

Researchers are increasingly interested in understanding how food environments influence eating behavior and weight-related health outcomes. Little is known about the dose-response relationship between foodscapes and behavior or weight, with measures of food exposure having mainly focused on fixed anchor points including residential neighborhoods, schools, or workplaces. Recent calls have been made to extend the consideration of environmental influences beyond local neighborhoods and also to shift away from place-based, to people-based, measures of exposure. This report presents analyses of novel activity-space measures of exposure to foodscapes, combining travel survey data with food store locations in Montreal and Quebec City, Canada. The resulting individual activity-space experienced foodscape exposure measures differ from traditional residential-based measures, and show variations by age and income levels. Furthermore, these activity-space exposure measures once modeled, can be used as predictors of health outcomes. Hence, travel surveys can be used to estimate environmental exposure for health survey participants.

Neighbourhood socioeconomic status, maternal education and adverse birth outcomes among mothers living near highways

Background: Residential proximity to highways is a potential proxy for exposure to traffic-related pollution that has been linked to adverse birth outcomes. We evaluated whether proximity to highway interacts with individual and neighbourhood socioeconomic status (SES) to influence birth outcomes. Methods: The study population consisted of all live singleton births in Montréal, Canada, from 1997 to 2001 (n = 99 819). Proximity was defined as residing within 200 m of a highway. Neighbourhood SES was measured for census tracts as the proportion of families below the low-income threshold. Individual SES was represented by maternal education. Using multilevel logistic regression, the odds of preterm birth (PTB), low birthweight (LBW) and small-for-gestational-age (SGA) birth were calculated for mothers residing in proximity to highways, accounting for individual and neighbourhood SES. Effect modification between SES and proximity to highway was tested for each outcome. Results: In wealthy neighbourhoods, proximity to highway was associated with an elevated odds of PTB (OR 1.58, 95% CI 1.23 to 2.04), LBW (OR 1.81, 95% CI 1.36 to 2.41) and SGA birth (OR 1.32, 95% CI 1.05 to 1.66). For highly educated mothers, proximity to highway was associated with PTB (OR 1.25, 95% CI 1.07 to 1.46) and LBW (OR 1.24, 95% CI 1.03 to 1.49), but the association was borderline for SGA birth (OR 1.15, 95% CI 1.00 to 1.32). Proximity to highway was not associated with birth outcomes in other maternal and neighbourhood SES categories. Conclusion: Counterintuitively, high SES mothers may be more likely than low SES mothers to experience adverse births associated with residential proximity to highway.

Social capital and core network ties: A validation study of individual-level social capital measures and their association with extra- and intra-neighborhood ties, and self-rated health

Research on social capital and health has assumed that measures of trust, participation, and perceived cohesion capture aspects of peoples neighborhood social connections. This study uses data on the personal networks of 2707 Montreal adults in 300 different neighborhoods to examine the association of socio-demographic and social capital variables with the likelihood of having core ties, core neighborhood ties, and high self-rated health (SRH). Persons with higher household income were more likely to have core ties, but less likely to have core neighborhood ties. Persons with greater diversity in extra-neighborhood network capital were more likely to have core ties, and persons with greater diversity in intra-neighborhood network capital were more likely to have core neighborhood ties. Generalized trust, perceived neighborhood cohesion, and extra-neighborhood network diversity were shown associated with high SRH. Conventional measures of social capital may not capture network mechanisms. Findings suggest a critical appraisal of the mechanisms linking social capital and health, and the further delineation of network and psychosocial mechanisms in understanding these links.

Field validation of listings of food stores and commercial physical activity establishments from secondary data.

BackgroundFood- and activity-related establishments are increasingly viewed as neighbourhood resources that potentially condition health-related behaviour. The primary objective of the current study was to establish, using ground truthing (on-site verification), the validity of measures of availability of food stores and physical activity establishments that were obtained from commercial database and Internet searches. A secondary objective was to examine differences in validity results according to neighbourhood characteristics and commercial establishment categories.MethodsLists of food stores and physical activity-related establishments in 12 census tracts within the Montreal metropolitan region were compiled using a commercial database (n = 171 establishments) and Internet search engines (n = 123 establishments). Ground truthing through field observations was performed to assess the presence of listed establishments and identify those absent. Percentage agreement, sensitivity (proportion of establishments found in the field that were listed), and positive predictive value (proportion of listed establishments found in the field) were calculated and contrasted according to data sources, census tracts characteristics, and establishment categories.ResultsAgreement with field observations was good (0.73) for the commercial list, and moderate (0.60) for the Internet-based list. The commercial list was superior to the Internet-based list for correctly listing establishments present in the field (sensitivity), but slightly inferior in terms of the likelihood that a listed establishment was present in the field (positive predictive value). Agreement was higher for food stores than for activity-related establishments.ConclusionCommercial data sources may provide a valid alternative to field observations and could prove a valuable tool in the evaluation of commercial environments relevant to eating behaviour. In contrast, this study did not find strong evidence in support of commercial and Internet data sources to represent neighbourhood opportunities for active lifestyle.

Social Inequalities in Food Exposure Around Schools in an Urban Area

BACKGROUND The obesity epidemic among children and youth, and the social gradient in this relationship, could be related to differential exposure to food sources in primary environments. Although the positive association between area-level deprivation and fast-food outlets offering high-calorie foods has been well documented, few studies have evaluated food sources around school settings. PURPOSE This study evaluated the relationships among food sources around schools, neighborhood income, and commercial density. METHODS A GIS was used to derive measures of exposure to fast-food outlets, fruit and vegetable stores, and full-service restaurants near primary and secondary schools in Montreal, Canada, in 2005. Food source availability was analyzed in 2009 in relation to neighborhood income for the area around schools, accounting for commercial density. RESULTS For the 1168 schools identified, strong neighborhood income gradients were observed in relation to food sources. Relative to the highest income-quartile schools, the odds of a fast-food outlet being located within 750 m of a low income-quartile school was 30.9 (95% CI=19.6, 48.9). Similar relationships were observed for full-service restaurants (OR=77, 95% CI=35, 169.3) and fruit and vegetable stores (OR=29.6, 95% CI=18.8, 46.7). These associations were reduced, but remained significant in models accounting for commercial density. CONCLUSIONS Food source exposure around schools is inversely associated with neighborhood income, but commercial density partly accounts for this association. Further research is necessary to document food consumption among youth attending schools in relation to nearby food source opportunities.

Association between Activity Space Exposure to Food Establishments and Individual Risk of Overweight

Objective Environmental exposure to food sources may underpin area level differences in individual risk for overweight. Place of residence is generally used to assess neighbourhood exposure. Yet, because people are mobile, multiple exposures should be accounted for to assess the relation between food environments and overweight. Unfortunately, mobility data is often missing from health surveys. We hereby test the feasibility of linking travel survey data with food listings to derive food store exposure predictors of overweight among health survey participants. Methods Food environment exposure measures accounting for non-residential activity places (activity spaces) were computed and modelled in Montreal and Quebec City, Canada, using travel surveys and food store listings. Models were then used to predict activity space food exposures for 5,578 participants of the Canadian Community Health Survey. These food exposure estimates, accounting for daily mobility, were used to model self-reported overweight in a multilevel framework. Median Odd Ratios were used to assess the proportion of between-neighborhood variance explained by such food exposure predictors. Results Estimates of food environment exposure accounting for both residential and non-residential destinations were significantly and more strongly associated with overweight than residential-only measures of exposure for men. For women, residential exposures were more strongly associated with overweight than non-residential exposures. In Montreal, adjusted models showed men in the highest quartile of exposure to food stores were at lesser risk of being overweight considering exposure to restaurants (OR = 0.36 [0.21–0.62]), fast food outlets (0.48 [0.30–0.79]), or corner stores (0.52 [0.35–0.78]). Conversely, men experiencing the highest proportion of restaurants being fast-food outlets were at higher risk of being overweight (2.07 [1.25–3.42]). Women experiencing higher residential exposures were at lower risk of overweight. Conclusion Using residential neighbourhood food exposure measures may underestimate true exposure and observed associations. Using mobility data offers potential for deriving activity space exposure estimates in epidemiological models.

Use of a new public bicycle share program in Montreal, Canada.

BACKGROUND Cycling contributes to physical activity and health. Public bicycle share programs (PBSPs) increase population access to bicycles by deploying bicycles at docking stations throughout a city. Minimal research has systematically examined the prevalence and correlates of PBSP use. PURPOSE To determine the prevalence and correlates of use of a new public bicycle share program called BIXI (name merges the word BIcycle and taXI) implemented in May 2009 in Montreal, Canada. METHODS A total of 2502 adults were recruited to a telephone survey in autumn 2009 via random-digit dialing according to a stratified random sampling design. The prevalence of BIXI bicycle use was estimated. Multivariate logistic regression allowed for identification of correlates of use. Data analysis was conducted in spring and summer 2010. RESULTS The unweighted mean age of respondents was 47.4 (SD=16.8) years and 61.4% were female. The weighted prevalence for use of BIXI bicycles at least once was 8.2%. Significant correlates of BIXI bicycle use were having a BIXI docking station within 250 m of home, being aged 18-24 years, being university educated, being on work leave, and using cycling as the primary mode of transportation to work. CONCLUSIONS A newly implemented public bicycle share program attracts a substantial fraction of the population and is more likely to attract younger and more educated people who currently use cycling as a primary transportation mode.