Nancy A. Ross

Relation between income inequality and mortality in Canada and in the United States; cross sectional assessment using census data and vital statistics

Abstract Objective: To compare the relation between mortality and income inequality in Canada with that in the United States. Design: The degree of income inequality, defined as the percentage of total household income received by the less well off 50% of households, was calculated and these measures were examined in relation to all cause mortality, grouped by and adjusted for age. Setting: The 10 Canadian provinces, the 50 US states, and 53 Canadian and 282 US metropolitan areas. Results: Canadian provinces and metropolitan areas generally had both lower income inequality and lower mortality than US states and metropolitan areas. In age grouped regression models that combined Canadian and US metropolitan areas, income inequality was a significant explanatory variable for all age groupings except for elderly people. The effect was largest for working age populations, in which a hypothetical 1% increase in the share of income to the poorer half of households would reduce mortality by 21 deaths per 100 000. Within Canada, however, income inequality was not significantly associated with mortality. Conclusions: Canada seems to counter the increasingly noted association at the societal level between income inequality and mortality. The lack of a significant association between income inequality and mortality in Canada may indicate that the effects of income inequality on health are not automatic and may be blunted by the different ways in which social and economic resources are distributed in Canada and in the United States.

The determinants of First Nation and Inuit health: a critical population health approach.

Environmental dispossession disproportionately affects the health of Canadas Aboriginal population, yet little is known about how its effects are sustained over time. We use a critical population health approach to explore the determinants of health in rural and remote First Nation and Inuit communities, and to conceptualize the pathways by which environmental dispossession affects these health determinants. We draw from narrative analysis of interviews with 26 Community Health Representatives (CHRs) from First Nation and Inuit communities across Canada. CHRs identified six health determinants: balance, life control, education, material resources, social resources, and environmental/cultural connections. CHRs articulated the role of the physical environment for health as inseparable from that of their cultures. Environmental dispossession was defined as a process with negative consequences for health, particularly in the social environment. Health research should focus on understanding linkages between environmental dispossession, cultural identity, and the social determinants of health.

BMI and mortality: results from a National Longitudinal Study of Canadian adults.

Although a clear risk of mortality is associated with obesity, the risk of mortality associated with overweight is equivocal. The objective of this study is to estimate the relationship between BMI and all‐cause mortality in a nationally representative sample of Canadian adults. A sample of 11,326 respondents aged ≥25 in the 1994/1995 National Population Health Survey (Canada) was studied using Cox proportional hazards models. A significant increased risk of mortality over the 12 years of follow‐up was observed for underweight (BMI <18.5; relative risk (RR) = 1.73, P < 0.001) and obesity class II+ (BMI >35; RR = 1.36, P <0.05). Overweight (BMI 25 to <30) was associated with a significantly decreased risk of death (RR = 0.83, P < 0.05). The RR was close to one for obesity class I (BMI 30–35; RR = 0.95, P >0.05). Our results are similar to those from other recent studies, confirming that underweight and obesity class II+ are clear risk factors for mortality, and showing that when compared to the acceptable BMI category, overweight appears to be protective against mortality. Obesity class I was not associated with an increased risk of mortality.

Body Mass Index in Urban Canada: Neighborhood and Metropolitan Area Effects

OBJECTIVES We investigated the influence of neighborhood and metropolitan area characteristics on body mass index (BMI) in urban Canada in 2001. METHODS We conducted a multilevel analysis with data collected from a cross-sectional survey of men and women nested in neighborhoods and metropolitan areas in urban Canada during 2001. RESULTS After we controlled for individual sociodemographic characteristics and behaviors, the average BMIs of residents of neighborhoods in which a large proportion of individuals had less than a high school education were higher than those BMIs of residents in neighborhoods with small proportions of such individuals (P< .01). Living in a neighborhood with a high proportion of recent immigrants was associated with lower BMI for men (P<.01), but not for women. Neighborhood dwelling density was not associated with BMI for either gender. Metropolitan sprawl was associated with higher BMI for men (P=.02), but the effect was not significant for women (P= .09). CONCLUSIONS BMI is strongly patterned by an individuals social position in urban Canada. A neighborhoods social condition has an incremental influence on the average BMI of its residents. However, BMI is not influenced by dwelling density. Metropolitan sprawl is associated with higher BMI for Canadian men, which supports recent evidence of this same association among American men. Individuals and their environments collectively influence BMI in urban Canada.

Postmenopausal breast cancer is associated with exposure to traffic-related air pollution in Montreal, Canada: a case-control study.

Background Only about 30% of cases of breast cancer can be explained by accepted risk factors. Occupational studies have shown associations between the incidence of breast cancer and exposure to contaminants that are found in ambient air. Objectives We sought to determine whether the incidence of postmenopausal breast cancer is associated with exposure to urban air pollution. Methods We used data from a case–control study conducted in Montreal, Quebec, in 1996–1997. Cases were 383 women with incident invasive breast cancer, and controls were 416 women with other incident, malignant cancers, excluding those potentially associated with selected occupational exposures. Concentrations of nitrogen dioxide (NO2) were measured across Montreal in 2005–2006. We developed a land-use regression model to predict concentrations of NO2 across Montreal for 2006, and developed two methods to extrapolate the estimates to 1985 and 1996. We linked these estimates to addresses of residences of subjects at time of interview. We used unconditional logistic regression to adjust for accepted and suspected risk factors and occupational exposures. Results For each increase of 5 ppb NO2 estimated in 1996, the adjusted odds ratio was 1.31 (95% confidence interval, 1.00–1.71). Although the size of effect varied somewhat across periods, we found an increased risk of approximately 25% for every increase of 5 ppb in exposure. Conclusions We found evidence of an association between the incidence of postmenopausal breast cancer and exposure to ambient concentrations of NO2. Further studies are needed to confirm whether NO2 or other components of traffic-related pollution are indeed associated with increased risks.

Social Support and Thriving Health: A New Approach to Understanding the Health of Indigenous Canadians

OBJECTIVES We examined the importance of social support in promoting thriving health among indigenous Canadians, a disadvantaged population. METHODS We categorized the self-reported health status of 31625 adult indigenous Canadians as thriving (excellent, very good) or nonthriving (good, fair, poor). We measured social support with indices of positive interaction, emotional support, tangible support, and affection and intimacy. We used multivariable logistic regression analyses to estimate odds of reporting thriving health, using social support as the key independent variable, and we controlled for educational attainment and labor force status. RESULTS Compared with women reporting low levels of social support, those reporting high levels of positive interaction (odds ratio [OR]=1.4; 95% confidence interval [CI]=1.2, 1.6), emotional support (OR=2.1; 95% CI=1.8, 2.4), and tangible support (OR = 1.4; 95% CI = 1.2, 1.5) were significantly more likely to report thriving health. Among men, only emotional support was significantly related to thriving health (OR=1.7; 95% CI=1.5, 1.9). Thriving health status was also significantly mediated by age, aboriginal status (First Nations, Métis, or Inuit), educational attainment, and labor force status. CONCLUSIONS Social support is a strong determinant of thriving health, particularly among women. Research that emphasizes thriving represents a positive and necessary turn in the indigenous health discourse.

Deprivation and the development of obesity a multilevel, longitudinal study in England

BACKGROUND Evidence indicates that the rising trend in overweight and obesity may be stronger for people from more socioeconomically advantaged backgrounds. PURPOSE This study used longitudinal, multilevel data to describe trajectories of BMI for people living in more- versus less-deprived neighborhoods. METHODS Data from 2501 women and 5650 men in the Whitehall II study who were followed for up to 13 years from 1991 to 2004 were analyzed in 2009. BMI was measured on up to three occasions by a trained nurse. The Townsend index of multiple deprivation at census-ward level from the 1991 U.K. census captured neighborhood deprivation. Growth curves summarized change in BMI for men and women according to level of neighborhood deprivation, adjusted for age, individual socioeconomic position (captured by civil service employment grade), smoking status, alcohol intake, and physical activity level. RESULTS Women who remained in the most-deprived neighborhoods between 1991 and 2004 had higher initial BMI and greater weight gain. Compared to those in the least-deprived neighborhoods, weight gain for a woman of average height in one of the most-deprived neighborhoods was 1.0 kg more over 10 years. Neither BMI nor change in BMI in men was associated with neighborhood deprivation. CONCLUSIONS Whitehall II provides longitudinal evidence of socioeconomic differences in weight gain among middle-aged women, indicating that the neighborhood environment makes a contribution to the development of overweight and obesity.

Double burden of deprivation and high concentrations of ambient air pollution at the neighbourhood scale in Montreal, Canada.

Some neighbourhoods in urban areas are characterised by concentrations of socially and materially deprived populations. Additionally, levels of ambient air pollution in a city can be variable at the local scale and can create disparities in air quality between neighbourhoods. Socioeconomic and physical characteristics of neighbourhood environments can affect the health and well-being of local residents. In this paper we identify whether neighbourhoods in Montreal, Canada characterised by social and material deprivation have higher levels of ambient air pollution than do others. We collected two-week integrated samples of nitrogen dioxide (NO(2)) at 133 sites in Montreal during three seasons between 2005 and 2006. We used these data in a geographic information system, along with data describing characteristics of land use, roads, and traffic, to create a spatial model of predicted mean annual concentrations of NO(2) across Montreal. Next, we collected neighbourhood socioeconomic information for 501 census tracts and overlaid their boundaries on the pollution surface. We calculated Pearson correlation coefficients and 95% confidence intervals (CI) between neighbourhood-level indicators of deprivation and levels of ambient NO(2). We found associations between concentrations of NO(2) and neighbourhood-level indicators of material deprivation, including median household income, and with indicators of social deprivation, including proportion of people living alone. We identified specific neighbourhoods that were characterised by a double burden of high levels of deprivation and high concentrations of ambient NO(2). Because of the particular social geography in Montreal, we found that not all deprived neighbourhoods had high levels of pollution and that some affluent neighbourhoods in the downtown core had high levels. Our results underscore the importance of considering social contexts in interpreting general associations between social and environmental risks to population health.

Social support, material circumstance and health behaviour: Influences on health in First Nation and Inuit communities of Canada

An expansive literature describes the links between social support and health. Though the bulk of this evidence emphasizes the health-enhancing effect of social support, certain aspects can have negative consequences for health (e.g., social obligations). In the Canadian context, the geographically small and socially interconnected nature of First Nation and Inuit communities provides a unique example through which to explore this relationship. Despite reportedly high levels of social support, many First Nation and Inuit communities endure broad social problems, thereby leading us to question the assumption that social support is primarily health protective. We draw from narrative analysis of interviews with 26 First Nation and Inuit Community Health Representatives to critically examine the health and social support relationship, and the social structures through which social support influences health. Findings indicate that there are health-enhancing and health-damaging properties of the health-social support relationship, and that the negative dimensions can significantly outweigh the positive ones. Social support operates at different structural levels, beginning with the individual and extending toward family and community. These social structures are important as they reinforce an individuals sense of belonging, however, these high-density networks can also exert conformity pressures and social obligations that promote health-damaging behaviours such as domestic violence and smoking. The poor material circumstances that characterize so many First Nation and Inuit communities add another layer of complexity as limited resources can trap individuals within the confines of their immediate social contexts. Research and policy interventions must pay close attention to the social context within which social support, health behaviours and material circumstances interact to influence health outcomes among First Nation and Inuit communities.

Metropolitan income inequality and working-age mortality: A cross-sectional analysis using comparable data from five countries

The relationship between income inequality and mortality has come into question as of late from many within-country studies. This article examines the relationship between income inequality and working-age mortality for metropolitan areas (MAs) in Australia, Canada, Great Britain, Sweden, and the United States to provide a fuller understanding of national contexts that produce associations between inequality and mortality. An ecological cross-sectional analysis of income inequality (as measured by median share of income) and working-age (25–64) mortality by using census and vital statistics data for 528 MAs (population >50,000) from five countries in 1990–1991 was used. When data from all countries were pooled, there was a significant relationship between income inequality and mortality in the 528 MAs studied. A hypothetical increase in the share of income to the poorest half of households of 1% was associated with a decline in working-age mortality of over 21 deaths per 100,000. Within each country, however, a significant relationship between inequality and mortality was evident only for MAs in the United States and Great Britain. These two countries had the highest average levels of income inequality and the largest populations of the five countries studied. Although a strong ecological association was found between income inequality and mortality across the 528 MAs, an association between income inequality and mortality was evident only in within-country analyses for the two most unequal countries: the United States and Great Britain. The absence of an effect of metropolitan-scale income inequality on mortality in the more egalitarian countries of Canada. Australia, and Sweden is suggestive of national-scale policies in these countries that buffer hypothetical effects of income inequality as a determinant of population health in industrialized economies.