Michael Tjepkema

Mortality among residents of shelters, rooming houses, and hotels in Canada: 11 year follow-up study

Objective To examine mortality in a representative nationwide sample of homeless and marginally housed people living in shelters, rooming houses, and hotels. Design Follow-up study. Setting Canada 1991-2001. Participants 15 100 homeless and marginally housed people enumerated in 1991 census. Main outcome measures Age specific and age standardised mortality rates, remaining life expectancies at age 25, and probabilities of survival from age 25 to 75. Data were compared with data from the poorest and richest income fifths as well as with data for the entire cohort Results Of the homeless and marginally housed people, 3280 died. Mortality rates among these people were substantially higher than rates in the poorest income fifth, with the highest rate ratios seen at younger ages. Among those who were homeless or marginally housed, the probability of survival to age 75 was 32% (95% confidence interval 30% to 34%) in men and 60% (56% to 63%) in women. Remaining life expectancy at age 25 was 42 years (42 to 43) and 52 years (50 to 53), respectively. Compared with the entire cohort, mortality rate ratios for men and women, respectively, were 11.5 (8.8 to 15.0) and 9.2 (5.5 to 15.2) for drug related deaths, 6.4 (5.3 to 7.7) and 8.2 (5.0 to 13.4) for alcohol related deaths, 4.8 (3.9 to 5.9) and 3.8 (2.7 to 5.4) for mental disorders, and 2.3 (1.8 to 3.1) and 5.6 (3.2 to 9.6) for suicide. For both sexes, the largest differences in mortality rates were for smoking related diseases, ischaemic heart disease, and respiratory diseases. Conclusions Living in shelters, rooming houses, and hotels is associated with much higher mortality than expected on the basis of low income alone. Reducing the excessively high rates of premature mortality in this population would require interventions to address deaths related to smoking, alcohol, and drugs, and mental disorders and suicide, among other causes.

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/m3 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. Citation Stieb DM, Chen L, Beckerman BS, Jerrett M, Crouse DL, Omariba DW, Peters PA, van Donkelaar A, Martin RV, Burnett RT, Gilbert NL, Tjepkema M, Liu S, Dugandzic RM. 2016. Associations of pregnancy outcomes and PM2.5 in a National Canadian Study. Environ Health Perspect 124:243–249; http://dx.doi.org/10.1289/ehp.1408995

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.

Data Resource Profile: 1991 Canadian Census Cohort

The 1991 Canadian Census Cohort is the largest population-based cohort in Canada (N=2,734,835). Prior to the creation of this Cohort, no national population-based Canadian cohort was available to examine mortality by socioeconomic indicators. The 1991 Canadian Census Cohort was created via the linkage of a sub-sample of respondents from the mandatory 1991 Canadian Census long-form to historical tax summary files, Canadian Mortality Database, Canadian Cancer Database, 1991 Health and Activity Limitation Survey and a sub-sample of the Longitudinal Worker File. Overall ascertainment of mortality and cancer is anticipated to be nearly complete and the Cohort is broadly representative of most groups in the Canadian population. The Cohort has been used to examine mortality outcomes by different indicators of socioeconomic status, occupational categories, ethnic groups, educational attainment, and for exposure to ambient air pollution. Results have shown that the estimated remaining years of life at age 25 differed substantially by income adequacy quintile, educational attainment, housing type and Aboriginal ancestry.

Suicide mortality by occupation in Canada, 1991-2001

Objective: To describe the association between occupation and risk of suicide among working-age men and women in Canada. Method: This study of suicide mortality over an 11-year period is based on a broadly representative 15% sample of the noninstitutionalized population of Canada aged 30 to 69 years at cohort inception. Age-standardized mortality rates (ASMRs) and rate ratios were calculated for men and women in 5 categories of skill level and 80 specific occupational groups, as well as for people not occupationally active. Results: The suicide mortality rate was 20.1/100 000 person years for occupationally active men (during 9 600 000 person years of follow-up) and 5.3/100 000 person years for occupationally active women (during 8 100 000 person years of follow-up). Among occupationally active men, elevated rates of suicide mortality were observed for 9 occupational groups and protective effects were observed for 6 occupational groups. Among women, elevated rates of suicide were observed in 4 occupational groups and no protective effects were observed. For men and women, ASMRs for suicide were inversely related to skill level. Conclusions: The limited number of associations between occupational groups and suicide risk observed in this study suggests that, with few exceptions, the characteristics of specific occupations do not substantially influence the risk for suicide. There was a moderate gradient in suicide mortality risk relative to occupational skill level. Suicide prevention strategies in occupational settings should continue to emphasize efforts to restrict and limit access to lethal means, one of the few suicide prevention policies with proven effectiveness.

Mortality following unemployment in Canada, 1991-2001

BackgroundThis study describes the association between unemployment and cause-specific mortality for a cohort of working-age Canadians.MethodsWe conducted a cohort study over an 11-year period among a broadly representative 15% sample of the non-institutionalized population of Canada aged 30–69 at cohort inception in 1991 (888,000 men and 711,600 women who were occupationally active). We used cox proportional hazard models, for six cause of death categories, two consecutive multi-year periods and four age groups, to estimate mortality hazard ratios comparing unemployed to employed men and women.ResultsFor persons unemployed at cohort inception, the age-adjusted hazard ratio for all-cause mortality was 1.37 for men (95% confidence interval (CI): 1.32-1.41) and 1.27 for women (95% CI: 1.20-1.35). The age-adjusted hazard ratio for unemployed men and women was elevated for all six causes of death: malignant neoplasms, circulatory diseases, respiratory diseases, alcohol-related diseases, accidents and violence, and all other causes. For unemployed men and women, hazard ratios for all-cause mortality were equivalently elevated in 1991–1996 and 1997–2001. For both men and women, the mortality hazard ratio associated with unemployment attenuated with age.ConclusionsConsistent with results reported from other long-duration cohort studies, unemployed men and women in this cohort had an elevated risk of mortality for accidents and violence, as well as for chronic diseases. The persistence of elevated mortality risks over two consecutive multi-year periods suggests that exposure to unemployment in 1991 may have marked persons at risk of cumulative socioeconomic hardship.

Spatial associations between socioeconomic groups and NO2 air pollution exposure within three large Canadian cities.

Previous studies of environmental justice in Canadian cities have linked lower socioeconomic status to greater air pollution exposures at coarse geographic scales, (i.e., Census Tracts). However, studies that examine these associations at finer scales are less common, as are comparisons among cities. To assess differences in exposure to air pollution among socioeconomic groups, we assigned estimates of exposure to ambient nitrogen dioxide (NO2), a marker for traffic-related pollution, from city-wide land use regression models to respondents of the 2006 Canadian census long-form questionnaire in Toronto, Montreal, and Vancouver. Data were aggregated at a finer scale than in most previous studies (i.e., by Dissemination Area (DA), which includes approximately 400-700 persons). We developed simultaneous autoregressive (SAR) models, which account for spatial autocorrelation, to identify associations between NO2 exposure and indicators of social and material deprivation. In Canadas three largest cities, DAs with greater proportions of tenants and residents who do not speak either English or French were characterised by greater exposures to ambient NO2. We also observed positive associations between NO2 concentrations and indicators of social deprivation, including the proportion of persons living alone (in Toronto), and the proportion of persons who were unmarried/not in a common-law relationship (in Vancouver). Other common measures of deprivation (e.g., lone-parent families, unemployment) were not associated with NO2 exposures. DAs characterised by selected indicators of deprivation were associated with higher concentrations of ambient NO2 air pollution in the three largest cities in Canada.

Cancer patterns in Inuit Nunangat: 1998-2007

Objectives . To compare cancer incidence patterns between residents of Inuit Nunangat and the rest of Canada. Study design . Cancer cases were geographically linked to either Inuit Nunangat or the rest of Canada using postal codes or other geographic information. Population estimates were derived from the 2001 and 2006 censuses. Methods . Cancer cases were combined from 1998 to 2007 for Inuit Nunangat and the rest of Canada. Age-standardised incidence rates were calculated for all site cancers and sub-sites by sex. Standardised rate ratios between these 2 areas were calculated for all site cancers and sub-sites. Results . The age-standardised incidence rate for all cancer sites (1998-2007) was 14% lower for the Inuit Nunangat male population and 29% higher for the female population by comparison to the rest of Canada. Cancers of the nasopharynx, lung and bronchus, colorectal, stomach (males), and kidney and renal pelvis (females), were elevated in the Inuit Nunangat population compared to the rest of Canada, whereas prostate and female breast cancers were lower in the Inuit Nunangat population. Conclusions . Cancers with potentially modifiable risk factors, such as buccal cavity and pharynx, nasopharynx, lung and bronchus, and colorectal cancer were elevated in the Inuit Nunangat population compared to the rest of Canada. Besides greater smoking prevalence within Inuit Nunangat by comparison to the rest of Canada, distinct socioeconomic characteristics between respective area populations including housing, and income may have contributed to incidence differentials. This study demonstrated that a geographic approach can be used in cancer surveillance when populations of interest are spatially distinguishable, and reside across distinct jurisdictions whose combined cancer registries will not completely provide information to identify the population of interest.Objectives . To compare cancer incidence patterns between residents of Inuit Nunangat and the rest of Canada. Study design . Cancer cases were geographically linked to either Inuit Nunangat or the rest of Canada using postal codes or other geographic information. Population estimates were derived from the 2001 and 2006 censuses. Methods . Cancer cases were combined from 1998 to 2007 for Inuit Nunangat and the rest of Canada. Age-standardised incidence rates were calculated for all site cancers and sub-sites by sex. Standardised rate ratios between these 2 areas were calculated for all site cancers and sub-sites. Results . The age-standardised incidence rate for all cancer sites (1998–2007) was 14% lower for the Inuit Nunangat male population and 29% higher for the female population by comparison to the rest of Canada. Cancers of the nasopharynx, lung and bronchus, colorectal, stomach (males), and kidney and renal pelvis (females), were elevated in the Inuit Nunangat population compared to the rest of Canada, whereas prostate and female breast cancers were lower in the Inuit Nunangat population. Conclusions . Cancers with potentially modifiable risk factors, such as buccal cavity and pharynx, nasopharynx, lung and bronchus, and colorectal cancer were elevated in the Inuit Nunangat population compared to the rest of Canada. Besides greater smoking prevalence within Inuit Nunangat by comparison to the rest of Canada, distinct socioeconomic characteristics between respective area populations including housing, and income may have contributed to incidence differentials. This study demonstrated that a geographic approach can be used in cancer surveillance when populations of interest are spatially distinguishable, and reside across distinct jurisdictions whose combined cancer registries will not completely provide information to identify the population of interest.Objectives . To compare cancer incidence patterns between residents of Inuit Nunangat and the rest of Canada. Study design . Cancer cases were geographically linked to either Inuit Nunangat or the rest of Canada using postal codes or other geographic information. Population estimates were derived from the 2001 and 2006 censuses. Methods . Cancer cases were combined from 1998 to 2007 for Inuit Nunangat and the rest of Canada. Age-standardised incidence rates were calculated for all site cancers and sub-sites by sex. Standardised rate ratios between these 2 areas were calculated for all site cancers and sub-sites. Results . The age-standardised incidence rate for all cancer sites (1998-2007) was 14% lower for the Inuit Nunangat male population and 29% higher for the female population by comparison to the rest of Canada. Cancers of the nasopharynx, lung and bronchus, colorectal, stomach (males), and kidney and renal pelvis (females), were elevated in the Inuit Nunangat population compared to the rest of Canada, whereas prostate and female breast cancers were lower in the Inuit Nunangat population. Conclusions . Cancers with potentially modifiable risk factors, such as buccal cavity and pharynx, nasopharynx, lung and bronchus, and colorectal cancer were elevated in the Inuit Nunangat population compared to the rest of Canada. Besides greater smoking prevalence within Inuit Nunangat by comparison to the rest of Canada, distinct socioeconomic characteristics between respective area populations including housing, and income may have contributed to incidence differentials. This study demonstrated that a geographic approach can be used in cancer surveillance when populations of interest are spatially distinguishable, and reside across distinct jurisdictions whose combined cancer registries will not completely provide information to identify the population of interest.

Associations between fine particulate matter and mortality in the 2001 Canadian Census Health and Environment Cohort

Background: Large cohort studies have been used to characterise the association between long‐term exposure to fine particulate matter (PM2.5) air pollution with non‐accidental, and cause‐specific mortality. However, there has been no consensus as to the shape of the association between concentration and response. Methods: To examine the shape of this association, we developed a new cohort based on respondents to the 2001 Canadian census long‐form. We applied new annual PM2.5 concentration estimates based on remote sensing and ground measurements for Canada at a 1 km spatial scale from 1998 to 2011. We followed 2.4 million respondents who were non‐immigrants aged 25–90 years and did not reside in an institution over a 10 year period for mortality. Exposures were assigned as a 3‐year mean prior to the follow‐up year. Income tax files were used to account for residential mobility among respondents using postal codes, with probabilistic imputation used for missing postal codes in the tax data. We used Cox survival models to determine hazard ratios (HRs) for cause‐specific mortality. We also estimated Shape Constrained Health Impact Functions (a concentration‐response function) for selected causes of death. Results: In models stratified by age, sex, airshed, and population centre size, and adjusted for individual and neighbourhood socioeconomic variables, HR estimates for non‐accidental mortality were HR = 1.18 (95% CI: 1.15–1.21) per 10 &mgr;g/m3 increase in concentration. We observed higher HRs for cardiovascular disease (HR=1.25; 95% CI: 1.19–1.31), cardio‐metabolic disease (HR = 1.27; 95% CI: 1.21–1.33), ischemic heart disease (HR = 1.36; 95% CI: 1.28–1.44) and chronic obstructive pulmonary disease (COPD) mortality (HR = 1.24; 95% CI: 1.11–1.39) compared to HR for all non‐accidental causes of death. For non‐accidental, cardio‐metabolic, ischemic heart disease, respiratory and COPD mortality, the shape of the concentration‐response curve was supra‐linear, with larger differences in relative risk for lower concentrations. For both pneumonia and lung cancer, there was some suggestion that the curves were sub‐linear. Conclusions: Associations between ambient concentrations of fine particulate matter and several causes of death were non‐linear for each cause of death examined. HighlightsAssociations between PM2.5 and mortality were examined in a new Canadian cohort.Hazard ratios between NAC mortality and PM2.5 were 1.18 per 10 &mgr;g/m3 increase.The shape of the concentration‐response curve was non‐linear for all causes of death examined.

Socio-economic Inequalities in Cause-specific Mortality: A 16-year Follow-up Study

ObjectivesTo examine socio-economic inequalities in cause-specific mortality by examining the independent effects of education, occupation and income in a population-based study of working-age Canadian adults.MethodsThis is a secondary analysis of data from the 1991–2006 Canadian Census mortality and cancer follow-up study (n=2.7 million persons). For this analysis, the cohort was restricted to 2.3 million persons aged 25 to 64 at cohort inception, of whom 164,332 died during the follow-up period. Hazard ratios were calculated by educational attainment (4 levels), occupational skill (6 categories) and income adequacy (5 quintiles) for all-cause mortality and major causes of death. Models were run separately for men and women, controlled for multiple variables simultaneously, and some were stratified by 10-year age cohorts.ResultsThe magnitude of socio-economic inequalities in mortality differed by indicator of socio-economic position (education, occupation, or income), age group, sex, and cause of death. Compared to age-adjusted models, hazard ratios were attenuated but remained significant in models that adjusted for both age and all three indicators of socio-economic position simultaneously. Socio-economic inequalities in mortality were evident for most of the major causes of death examined.ConclusionThis study demonstrates that education, occupation and income were each independently associated with mortality and were not simply proxies for each other. When evaluating socio-economic inequalities in mortality, it is important to use different indicators of socio-economic position to provide a more complete picture.RésuméObjectifsÉtudier les inégalités socioéconomiques influant sur la mortalité selon la cause en examinant les effets indépendants du niveau de scolarité, de la profession et du revenu dans le cadre d’une étude basée sur la population d’adultes canadiens en âge de travailler.MéthodeIl s’agit d’une analyse secondaire des données de l’étude canadienne de suivi de la mortalité et du cancer selon le recensement, 1991–2006 (n=2,7 millions de personnes). Pour cette analyse, on a créé une cohorte limitée à 2,3 millions de personnes âgées de 25 à 64 ans, dont 164 332 sont décédées durant la période de suivi. Les rapports des risques ont été calculés pour toutes les causes confondues et les causes principales de décès, selon le niveau de scolarité (4 niveaux), les compétences professionnelles (6 catégories) et la suffisance du revenu (5 quintiles). On a exécuté des modèles séparément pour les hommes et les femmes, en tenant compte de variables multiples simultanément, et certains ont été stratifiés par cohortes d’âge de 10 ans.RésultatsL’ampleur des inégalités socioéconomiques influant sur la mortalité variait selon l’indicateur de la situation socioéconomique (niveau de scolarité, profession ou revenu), le groupe d’âge, le sexe et la cause de décès. Comparativement aux modèles ajustés en fonction de l’âge, les rapports des risques étaient atténués, mais demeuraient importants dans les modèles ajustés en fonction de l’âge et des trois indicateurs de la situation socioéconomique simultanément. Des inégalités socioéconomiques influant sur la mortalité ont été observées pour la plupart des causes principales de décès examinées.ConclusionCette étude démontre que le niveau de scolarité, la profession et le revenu étaient tous associés de manière indépendante à la mortalité et n’étaient pas simplement des variables de substitution l’une pour l’autre. Dans le cadre de l’étude des inégalités socioéconomiques influant sur la mortalité, il est important d’utiliser différents indicateurs de la situation socioéconomique afin de brosser un tableau plus complet.