A national study of the association between traffic-related air pollution and adverse pregnancy outcomes in Canada, 1999-2008.

Numerous studies have examined the association of air pollution with preterm birth and birth weight outcomes. Traffic-related air pollution has also increasingly been identified as an important contributor to adverse health effects of air pollution. We employed a national nitrogen dioxide (NO2) exposure model to examine the association between NO2 and pregnancy outcomes in Canada between 1999 and 2008. National models for NO2 (and particulate matter of median aerodynamic diameter <2.5µm (PM2.5) as a covariate) were developed using ground-based monitoring data, estimates from remote-sensing, land use variables and, for NO2, deterministic gradients relative to road traffic sources. Generalized estimating equations were used to examine associations with preterm birth, term low birth weight (LBW), small for gestational age (SGA) and term birth weight, adjusting for covariates including infant sex, gestational age, maternal age and marital status, parity, urban/rural place of residence, maternal place of birth, season, year of birth and neighbourhood socioeconomic status and per cent visible minority. Associations were reduced considerably after adjustment for individual covariates and neighbourhood per cent visible minority, but remained significant for SGA (odds ratio 1.04, 95%CI 1.02-1.06 per 20ppb NO2) and term birth weight (16.2g reduction, 95% CI 13.6-18.8g per 20ppb NO2). Associations with NO2 were of greater magnitude in a sensitivity analysis using monthly monitoring data, and among births to mothers born in Canada, and in neighbourhoods with higher incomes and a lower proportion of visible minorities. In two pollutant models, associations with NO2 were less sensitive to adjustment for PM2.5 than vice versa, and there was consistent evidence of a dose-response relationship for NO2 but not PM2.5. In this study of approximately 2.5 million Canadian births between 1999 and 2008, we found significant associations of NO2 with SGA and term birth weight which remained significant after adjustment for PM2.5, suggesting that traffic may be a particularly important source with respect to the role of air pollution as a risk factor for adverse pregnancy outcomes.

Associations of Pregnancy Outcomes and PM2.5 in a National Canadian Study.

BACKGROUND: Numerous studies have examined associations between air pollution and pregnancy outcomes, but most have been restricted to urban populations living near monitors. OBJECTIVES: We examined the association between pregnancy outcomes and fine particulate matter in a large national study including urban and rural areas. METHODS: Analyses were based on approximately 3 million singleton live births in Canada between 1999 and 2008. Exposures to PM2.5 (particles of median aerodynamic diameter ≤ 2.5 µm) were assigned by mapping the mother's postal code to a monthly surface based on a national land use regression model that incorporated observations from fixed-site monitoring stations and satellite-derived estimates of PM2.5. Generalized estimating equations were used to examine the association between PM2.5 and preterm birth (gestational age < 37 weeks), term low birth weight (< 2,500 g), small for gestational age (SGA; < 10th percentile of birth weight for gestational age), and term birth weight, adjusting for individual covariates and neighborhood socioeconomic status (SES). RESULTS: In fully adjusted models, a 10-µg/m(3) increase in PM2.5 over the entire pregnancy was associated with SGA (odds ratio = 1.04; 95% CI 1.01, 1.07) and reduced term birth weight (-20.5 g; 95% CI -24.7, -16.4). Associations varied across subgroups based on maternal place of birth and period (1999-2003 vs. 2004-2008). CONCLUSIONS: This study, based on approximately 3 million births across Canada and employing PM2.5 estimates from a national spatiotemporal model, provides further evidence linking PM2.5 and pregnancy outcomes.

Immigration, ethnicity, and avoidable mortality in Canada, 1991-2006.

OBJECTIVE: Avoidable mortality is a well-recognized, but less studied indicator of the performance of the health system. First, the study seeks to establish whether immigrants overall and selected foreign-born ethnic groups (Western Europeans, South Asians, Chinese, and Filipinos) have an advantage over nonimmigrants in avoidable mortality. Second, it assesses the effect of sociodemographic and socioeconomic factors on any observed differences by duration of residence. DESIGN: Deaths grouped by cause of death and by behavioral risk factors, namely smoking-related and alcohol-related, were derived from the 1991 Canadian Census Cohort: Mortality and Cancer Follow-up. The analysis estimated age-standardized mortality rates (ASMRs), rate ratios, and rate differences and also fitted hazard regression models for the overall Canadian-born population and for selected foreign-born ethnicities by sex. Predictors were assessed at baseline. RESULTS: Compared to the Canadian-born persons, foreign-born men and women had lower ASMRs for overall avoidable mortality and also for selected causes of avoidable mortality. The only exception to this overall trend was for ischemic heart disease among South Asian women. Except for the order of prominence, the three leading causes of death for nonimmigrant and immigrant men and women overall were ischemic heart diseases, smoking-related diseases, and neoplasms. A similar pattern was observed among the ethnic groups, except for circulatory heart diseases replacing ischemic heart diseases and smoking-related diseases among Chinese and Filipino women, respectively. In the hazard regression analysis, the risk of avoidable mortality was lower for immigrants overall and selected ethnicities irrespective of the duration in Canada compared to nonimmigrants. These differences persisted even with adjustment for sociodemographic and socioeconomic factors. CONCLUSION: Immigrants overall and the selected ethnicities enjoy an advantage over nonimmigrants in avoidable mortality. However, for certain causes of death especially ischemic heart disease mortality among South Asian women, immigrants appeared worse-off than nonimmigrants. The results suggest differential access to and use of health services, differences in protective health-related behavior, and the healthy immigrant effect.

Health literacy and disability: differences between generations of Canadian immigrants.

OBJECTIVES: To determine whether there are differences in disability by immigrant generation and region of origin and recency of arrival in Canada, and the role of health literacy in this relationship. METHODS: A secondary analysis of the Canadian component of the 2003 International Adult Literacy and Skills Survey (IALSS) was undertaken. RESULTS: Compared to the third-plus generation, first-generation immigrants were less likely to report disability; these differences remained even after adjustment for sociodemographic and socioeconomic factors. No differences in disability were observed between the second- and third-plus generations. Among first-generation immigrants, those not from Europe or USA were less likely to report disability regardless of their duration in Canada. Health literacy was negatively associated with disability only in the analysis comparing generations of Canadians. However, its effect was largely accounted for by education, employment status and income. CONCLUSIONS: First-generation immigrants were less likely to be disabled than the other generations. Education, employment and income provide important avenues through which individuals develop health literacy. Health literacy was not associated with disability among first-generation immigrants perhaps because health literacy is low in this group.

Differences between immigrants at various durations of residence and host population in all-cause mortality, Canada 1991-2006.

We used data from the 1991-2006 Canadian Census Mortality and Cancer Follow-up Study to compare all-cause mortality for immigrants with that of the Canadian-born population. The study addressed two related questions. First, do immigrants have a mortality advantage over the Canadian-born? Second, if immigrants have a mortality advantage, does it persist as their duration of residence increases? The analysis fitted sex-stratified hazard regression models for the overall sample and for selected countries of birth (UK, China, India, Philippines, and the Caribbean). Predictors were assessed at baseline. Mortality was lower among immigrants than the Canadian-born even after adjusting for a selected group of socio-demographic and socio-economic factors. The mortality differences persisted even after long residence in Canada, but appeared to be dependent on the age of the individual and the country of origin. Interpreted in light of known explanations of immigrant mortality advantage, the results mostly reflect selection effects.

Neighbourhood immigrant concentration and hospitalization: a multilevel analysis of cardiovascular-related admissions in Ontario using linked data.

OBJECTIVE: To assess the influence of neighbourhood immigrant concentration on cardiovascular-disease-related hospitalizations in Canada (CVDH), while adjusting for individual-level immigrant status and socio-economic indicators at individual and neighbourhood levels. METHODS: Data were from the 2006 Canadian Census linked to the hospital Discharge Abstract Data (DAD) for the province of Ontario. Adults (n=1,459,950) aged ≥18 years at baseline and grouped by place of birth (Canada, China, South Asia, Europe, and other) were followed between Census Day May 16, 2006 and March 31, 2008. Information on CVDH was obtained from the DAD, while that on immigration and socio-economic indicators was obtained from the Census. The analysis used multilevel logistic regression. RESULTS: Unadjusted results showed that CVDH was significantly lower among people living in neighbourhoods with medium and high immigrant concentration. Neighbourhood immigrant concentration tended to have no independent effect on CVDH after adjustment for individual-level immigrant status. Immigrants were less likely to experience CVDH irrespective of their country of birth. However, cross-level interaction showed that neighbourhood immigrant concentration provided additional protection to individual-level immigrant status against CVDH for most female immigrant groups, but only for South Asian males. CONCLUSION: This study resulted from the first-ever linkage of census data to hospitalization data in Canada. It is also the first Canadian study to report on neighbourhood variation and the effect of immigrant concentration on CVDH. The study shows that understanding immigrant health requires both individual and neighbourhood approaches, and a consideration of country of origin.

Canadian Cancer Risk Management Model: evaluation of cancer control.

OBJECTIVES: The aim of this study was to develop a decision support tool to assess the potential benefits and costs of new healthcare interventions. METHODS: The Canadian Partnership Against Cancer (CPAC) commissioned the development of a Cancer Risk Management Model (CRMM)--a computer microsimulation model that simulates individual lives one at a time, from birth to death, taking account of Canadian demographic and labor force characteristics, risk factor exposures, and health histories. Information from all the simulated lives is combined to produce aggregate measures of health outcomes for the population or for particular subpopulations. RESULTS: The CRMM can project the population health and economic impacts of cancer control programs in Canada and the impacts of major risk factors, cancer prevention, and screening programs and new cancer treatments on population health and costs to the healthcare system. It estimates both the direct costs of medical care, as well as lost earnings and impacts on tax revenues. The lung and colorectal modules are available through the CPAC Web site (www.cancerview.ca/cancerrriskmanagement) to registered users where structured scenarios can be explored for their projected impacts. Advanced users will be able to specify new scenarios or change existing modules by varying input parameters or by accessing open source code. Model development is now being extended to cervical and breast cancers.

Immigration, generation and self-rated health in Canada: on the role of health literacy.

OBJECTIVES: The purpose of this study was to determine whether there are differences in self-rated health by immigration and generational status, and the role of health literacy in this relationship. METHODS: Data were from the Canadian component of the 2003 International Adult Literacy and Skills Survey (IALSS) undertaken by Statistics Canada. The sample comprised a total of 22,818 persons, of whom 3,861 were immigrants and 18,957 non-immigrants. The study employed logistic regression to examine the relationship between health literacy and self-rated health. The analysis separately compared: immigrants and non-immigrants; immigrant groups defined by region of origin and recency of arrival in Canada; and the local-born defined by generation. RESULTS: Logistic regression results indicated that immigrants compared to non-immigrants, and recent immigrants not from Europe or USA compared to established immigrants from Europe or USA, were more likely to report good self-rated health. On the other hand, compared to the third-plus generation, the second generation were less likely to report good self-rated health. Health literacy was positively associated with good self-rated health. However, its effect was largely accounted for by discordance between mother tongue and language of survey administration among immigrants, and by literacy practices at home, education, place of residence, and income among non-immigrants. CONCLUSION: Health literacy is important in the health of both immigrants and non-immigrants, but with different underlying mechanisms. For non-immigrants, engaging in literacy practices at home would benefit both health literacy and overall health, whereas for immigrants, it would be improving proficiency in either English or French.

Gender differences in functional limitations among Canadians with arthritis: the role of disease duration and comorbidity.

BACKGROUND: Mechanisms underlying gender disparities in functional limitations among people with arthritis remain unclear. This study examined gender differences in the relationship between disease duration and comorbidity and functional limitations among people with arthritis. DATA AND METHODS: Data were from the arthritis component of the 2009 Survey on Living with Chronic Diseases in Canada. People were considered to have functional limitations if they reported that arthritis limits them "a lot" in activities of daily living. Those with no functional limitations were the reference group. Gender-stratified weighted multivariate binary logistic regression analyses were conducted. RESULTS: In a fully adjusted multivariate analysis, only among women was time elapsed since the arthritis diagnosis associated with functional limitations. Disabling and life-threatening chronic conditions were associated with functional limitations in both genders. Among men, obesity and low household income were associated with higher odds of functional limitations, while living in British Columbia was associated with decreased odds. For women, smoking, not engaging in physical activity, residing in a non-Atlantic province, and having excess weight increased the odds of functional limitations, while habitual alcohol drinking decreased the odds. INTERPRETATION: Gender differences in the risks of reporting functional limitations were significant. These differences appear to be driven by duration of having arthritis, and disparities in health behavioural factors, household income and region of residence. The association between chronic conditions and functional limitations was similar for men and women.

HIV/AIDS knowledge, women's education, epidemic severity and protective sexual behaviour in low- and middle-income countries.

A fundamental public health strategy to reduce the risk of HIV/AIDS is to increase levels of awareness and knowledge about the disease. Although knowledge about HIV/AIDS and protective sexual behaviour are linked theoretically, relatively little is known about their empirical relationship. Using Demographic and Health Survey data from 23 low- and middle-income countries, this study used multilevel logistic regression models: to examine cross-national variability in the relationship between HIV/AIDS knowledge and protective behaviour (condom use and restricted sex); to investigate the moderating influences of women's educational attainment on this relationship; and to test the extent to which severity of the HIV/AIDS epidemic accounts for cross-national variability in the association between HIV/AIDS knowledge and protective behaviour. There was an association between increased knowledge of HIV/AIDS and condom use that varied in strength and form cross-nationally. This cross-national variation was accounted for partially by the socioeconomic characteristics of women resident in the study countries and between-country differences in the severity of the HIV epidemic. While education modified the association between HIV/AIDS knowledge and protective behaviour--stronger associations at lower levels of education--epidemic severity exerted a stronger influence on behaviour than any other characteristic. Finally, this study indicates that protective sexual practices are disturbingly low. In eight of 23 countries, overall levels of condom use to prevent STDs and HIV/AIDS were less than 5.0%. Waiting for the spread of HIV/AIDS infection to change sexual practices in low- and middle-income countries will result in dramatic unnecessary suffering.

Women's educational attainment and intergenerational patterns of fertility behaviour in Kenya.

There is a strong theoretical and empirical relationship between educational attainment and fertility behaviour. However, a fundamental issue that has largely been neglected is the change in this relationship across cohorts resulting from differential improvement in educational opportunities for women over time and how it relates to fertility transition. Utilizing the 1998 DHS data from Kenya this study examines the differential effect of educational attainment on women's use of modern contraception and desire for cessation of childbearing across generations. The findings indicate that even after controlling for husband's education and other relevant factors, a woman's advanced education is positively associated with use of modern contraception. However, support for a similar hypothesis on a woman's desire for family limitation was only found among the youngest cohort of women. The results suggest that for Kenya's incipient fertility transition to be sustained the government needs to continue efforts to improve female education and support access to family planning among younger women.