Data obtained from longitudinal surveys using complex multi-stage sampling designs contain cross-sectional dependencies among units caused by inherent hierarchies in the data, and within subject correlation arising due to repeated measurements. The statistical methods used for analyzing such data should account for stratification, clustering and unequal probability of selection as well as within-subject correlations due to repeated measurements. <p>The complex multi-stage design approach has been used in the longitudinal National Population Health Survey (NPHS). This on-going survey collects information on health determinants and outcomes in a sample of the general Canadian population. <p>This dissertation compares the model-based and design-based approaches used to determine the risk factors of asthma prevalence in the Canadian female population of the NPHS (marginal model). Weighted, unweighted and robust statistical methods were used to examine the risk factors of the incidence of asthma (event history analysis) and of recurrent asthma episodes (recurrent survival analysis). Missing data analysis was used to study the bias associated with incomplete data. To determine the risk factors of asthma prevalence, the Generalized Estimating Equations (GEE) approach was used for marginal modeling (model-based approach) followed by Taylor Linearization and bootstrap estimation of standard errors (design-based approach). The incidence of asthma (event history analysis) was estimated using weighted, unweighted and robust methods. Recurrent event history analysis was conducted using Anderson and Gill, Wei, Lin and Weissfeld (WLW) and Prentice, Williams and Peterson (PWP) approaches. To assess the presence of bias associated with missing data, the weighted GEE and pattern-mixture models were used.<p>The prevalence of asthma in the Canadian female population was 6.9% (6.1-7.7) at the end of Cycle 5. When comparing model-based and design- based approaches for asthma prevalence, design-based method provided unbiased estimates of standard errors. The overall incidence of asthma in this population, excluding those with asthma at baseline, was 10.5/1000/year (9.2-12.1). For the event history analysis, the robust method provided the most stable estimates and standard errors. <p>For recurrent event history, the WLW method provided stable standard error estimates. Finally, for the missing data approach, the pattern-mixture model produced the most stable standard errors <p>To conclude, design-based approaches should be preferred over model-based approaches for analyzing complex survey data, as the former provides the most unbiased parameter estimates and standard errors.

Data obtained from longitudinal surveys using complex multi-stage sampling designs contain cross-sectional dependencies among units caused by inherent hierarchies in the data, and within subject correlation arising due to repeated measurements. The statistical methods used for analyzing such data should account for stratification, clustering and unequal probability of selection as well as within-subject correlations due to repeated measurements. <p>The complex multi-stage design approach has been used in the longitudinal National Population Health Survey (NPHS). This on-going survey collects information on health determinants and outcomes in a sample of the general Canadian population. <p>This dissertation compares the model-based and design-based approaches used to determine the risk factors of asthma prevalence in the Canadian female population of the NPHS (marginal model). Weighted, unweighted and robust statistical methods were used to examine the risk factors of the incidence of asthma (event history analysis) and of recurrent asthma episodes (recurrent survival analysis). Missing data analysis was used to study the bias associated with incomplete data. To determine the risk factors of asthma prevalence, the Generalized Estimating Equations (GEE) approach was used for marginal modeling (model-based approach) followed by Taylor Linearization and bootstrap estimation of standard errors (design-based approach). The incidence of asthma (event history analysis) was estimated using weighted, unweighted and robust methods. Recurrent event history analysis was conducted using Anderson and Gill, Wei, Lin and Weissfeld (WLW) and Prentice, Williams and Peterson (PWP) approaches. To assess the presence of bias associated with missing data, the weighted GEE and pattern-mixture models were used.<p>The prevalence of asthma in the Canadian female population was 6.9% (6.1-7.7) at the end of Cycle 5. When comparing model-based and design- based approaches for asthma prevalence, design-based method provided unbiased estimates of standard errors. The overall incidence of asthma in this population, excluding those with asthma at baseline, was 10.5/1000/year (9.2-12.1). For the event history analysis, the robust method provided the most stable estimates and standard errors. <p>For recurrent event history, the WLW method provided stable standard error estimates. Finally, for the missing data approach, the pattern-mixture model produced the most stable standard errors <p>To conclude, design-based approaches should be preferred over model-based approaches for analyzing complex survey data, as the former provides the most unbiased parameter estimates and standard errors.

Psychotropic medication use is widely implicated as a risk factor for injuries, and it is believed that the adverse effect profiles of these medications are exacerbated by the consumption of alcohol. The objectives of this study are (a) to examine the associations between the use of specific classes of psychotropic medications and injuries among elderly participants of the National Population Health Survey (NPHS), and (b) to determine whether and how associations between psychotropic medications and injuries are modified by the consumption of alcohol. Data from Cycles 1 (1994/95), 2 (1996/97), and 3 (1998/99) of the NPHS household longitudinal file were used in this study, selecting community-dwelling participants aged 65 years of age and older in 1994/95. Among antidepressant medications, the magnitude of the risk of injuries was higher for users of tricyclic derivatives (OR=1.4; 95%CI: 0.7 – 2.9) than SSRIs (OR=0.3; 95%CI: 0.1 – 1.0). Benzodiazepine use for any indication increased the risk of injuries, but that effect was not consistent across indications. The use of benzodiazepine antianxiety medications resulted in an increased risk of injuries (OR=2.0; 95%CI: 1.3 – 3.1), but there were no significant effects on the injury risk among benzodiazepine hypnotic and sedative users (OR=0.8; 95%CI: 0.4 – 1.7). Results pertaining to the second objective of this study raised as many questions as they resolved. Alcohol consumption decreased the odds of injury among hypnotic and sedative users, but otherwise, no consistent results were observed. Findings from this study underscore the importance of identifying appropriate alcohol measures for research among elderly populations. They also stress the need to separately consider the impact of different classes of psychotropic medications on injuries (tricyclic antidepressants separate from SSRI antidepressants and antianxiety benzodiazepines separate from hypnotic and sedative benzodiazepines).

Psychotropic medication use is widely implicated as a risk factor for injuries, and it is believed that the adverse effect profiles of these medications are exacerbated by the consumption of alcohol. The objectives of this study are (a) to examine the associations between the use of specific classes of psychotropic medications and injuries among elderly participants of the National Population Health Survey (NPHS), and (b) to determine whether and how associations between psychotropic medications and injuries are modified by the consumption of alcohol. Data from Cycles 1 (1994/95), 2 (1996/97), and 3 (1998/99) of the NPHS household longitudinal file were used in this study, selecting community-dwelling participants aged 65 years of age and older in 1994/95. Among antidepressant medications, the magnitude of the risk of injuries was higher for users of tricyclic derivatives (OR=1.4; 95%CI: 0.7 – 2.9) than SSRIs (OR=0.3; 95%CI: 0.1 – 1.0). Benzodiazepine use for any indication increased the risk of injuries, but that effect was not consistent across indications. The use of benzodiazepine antianxiety medications resulted in an increased risk of injuries (OR=2.0; 95%CI: 1.3 – 3.1), but there were no significant effects on the injury risk among benzodiazepine hypnotic and sedative users (OR=0.8; 95%CI: 0.4 – 1.7). Results pertaining to the second objective of this study raised as many questions as they resolved. Alcohol consumption decreased the odds of injury among hypnotic and sedative users, but otherwise, no consistent results were observed. Findings from this study underscore the importance of identifying appropriate alcohol measures for research among elderly populations. They also stress the need to separately consider the impact of different classes of psychotropic medications on injuries (tricyclic antidepressants separate from SSRI antidepressants and antianxiety benzodiazepines separate from hypnotic and sedative benzodiazepines).

L’ampleur des problèmes de santé mentale, les coûts qui en découlent et le lien établi entre le travail et les problèmes de santé mentale sont autant d’éléments qui expliquent l’intérêt croissant pour les interventions en santé mentale au travail. Dans un contexte où la personnalisation des interventions en santé mentale est davantage encouragée, les traits d’identité culturelle pourraient contribuer à une telle personnalisation. Nous définissons un trait d’identité culturelle comme un élément matériel ou non matériel d'une identité culturelle, hérité ou non héritée, considéré comme isolable et susceptible d'une analyse spécifique. Personnaliser les interventions en santé mentale suivant les traits d’identité culturelle implique d’adapter ces interventions, de manière à répondre aux situations spécifiques en milieu de travail dans lesquelles les traits d’identité culturelle pourraient agir comme des facteurs importants. Cette thèse de doctorat est un début de réponse sur l’intérêt ou non d’une telle démarche. Cette thèse vise à mieux comprendre en quoi les traits d’identité culturelle, plus particulièrement l’ethnicité et le statut d’immigrant, pourraient modifier la façon dont le travail s’associe aux symptômes de détresse psychologique et aux symptômes dépressifs dans la main-d’œuvre canadienne. La place limitée réservée aux traits d’identité culturelle dans les modèles dominants du stress au travail représente un obstacle à la compréhension du rôle des traits d’identité culturelle dans l’association qui relie le travail aux problèmes de santé mentale. Or les traits d’identité culturelle sont à la fois associés au travail et à la santé mentale. La composition de la population canadienne justifie toute aussi la pertinence d’intégrer les traits d’identité culturelle dans l’analyse du travail et de la santé mentale, car un peu plus de 250 000 nouveaux immigrants entrent sur le territoire canadien chaque année. Parmi ceux-ci, environ 80% proviennent d'Asie, d’Afrique, et d’Amérique latine. Or les immigrants et les personnes issues des minorités visibles semblent plus à risques de se retrouver dans des conditions de travail plus contraignantes. Ces deux groupes semblent également avoir en général une prévalence de symptômes de détresse psychologique et de dépression élevée. Afin de contourner les limites inhérentes aux modèles dominants du stress au travail, nous avons pris appui dans cette étude sur le modèle multiniveaux du stress au travail inspiré de la théorie du stress social; et des approches sociologiques abordées aux États-Unis dans une perspective micro-macro et en Europe dans une perspective d’agent-structure. La théorie du stress social permet de comprendre les mécanismes qui lient certaines conditions de l’organisation sociale à la santé mentale. Les approches micro-macro et d’agent structure s’intéressent non seulement à scinder la réalité sociale en niveaux, mais essayent également de comprendre le sens de la relation entre les différents niveaux. Le modèle théorique proposé présente trois principales hypothèses dans lesquelles les variables du travail à l’exception de la déqualification sont inspirées de celles retrouvées dans le modèle multiniveaux. Ces hypothèses postulent 1) une relation directe entre les traits d’identité culturelle (le statut d’immigrant et l’ethnicité) et les problèmes de santé mentale (symptômes de détresse psychologique et symptômes dépressifs); 2) un rôle modérateur des traits d’identité culturelle entre les facteurs du travail (déqualification, utilisation des compétences, autorité décisionnelle, demandes psychologiques, demandes physiques, soutien social au travail, insécurité d'emploi, heures travaillées, horaire irrégulier) et les problèmes de santé mentale; 3) un rôle médiateur des facteurs du travail dans la relation entre les traits d’identité culturelle et les problèmes de santé mentale. Grâce à l’analyse de médiation, nous avons également testé la possibilité d’une exposition différentielle aux facteurs du travail selon les traits d’identité culturelle. Nous avons utilisé les données longitudinales de l’Enquête nationale sur la santé de la population (ENSP) menée par Statistique Canada. Les données ont été collectées sur une période de 18 ans, débutée en 1994 et terminée en 2012 après 9 cycles. Des analyses de régressions multiples et multiniveaux ont été menées sur un échantillon de 6 477 travailleurs. Les résultats des analyses sont présentés sous forme de trois articles retrouvés aux chapitres 5 à 7. Les résultats suggèrent un rôle de l’ethnicité dans la relation entre le travail et les symptômes analysés. En effet, l’ethnicité semble s’associer aux symptômes dépressifs, mais pas aux symptômes de détresse psychologique. Des multiples effets de modération et de médiation testés, seul un effet s’est avéré significatif. Il s’agit du rôle médiateur de l’utilisation des compétences dans la relation entre l’ethnicité et les symptômes de détresse psychologique. Il semble également exister certaines expositions différentielles au travail de par l’ethnicité. Les personnes issues des minorités visibles semblent exposées de manière différentielle à plus de déqualification, à moins d’utilisation des compétences, et à moins d’autorité décisionnelle en comparaison à celles qui sont caucasiennes. L’analyse du rôle du statut d’immigrant dans la relation entre le travail et les symptômes analysés s’est avérée non concluante. De nombreuses limites inhérentes à notre stratégie de recherche (mesure de l’ethnicité, non prise en compte de la qualité de l’emploi, non-distinction des catégories d’immigrants, immigrants en majorité de longue date, variables de contrôle ne témoignant pas de nombreuses réalités du processus migratoire et d’intégration, etc.) appel à être prudent quant à l’interprétation faite des résultats de cette thèse. Les résultats de cette thèse ne permettent pas de mettre un point final sur la question du lien entre les traits d’identités culturelles, le travail et la santé mentale. Toutefois, ils y apportent un certain éclairage. Ils laissent penser que réduire les conditions de travail à risque et combattre l’exposition différentielle aux facteurs du travail pourraient offrir deux axes d’interventions contre les problèmes de santé mentale dans la main-d’œuvre canadienne. Intervenir sur ces deux pôles pourrait également contribuer à baisser les dépenses en santé mentale qui semblent de plus en plus importantes au Canada. Un élément qui semble ressortir le plus de cette étude est bien la nécessité de se pencher davantage sur la question de la déqualification professionnelle. / The increased disability claims linked to mental health problems, the economic implications of mental illness in terms of costs for businesses, and the established link between work and mental health are some of the rising concerns explaining the growing interest in mental health interventions and programs in the workplace. In a context where the personalization of mental health interventions is further promoted, cultural identity traits could contribute to such a personalization. We define cultural identity traits as a tangible or intangible element of a cultural identity, inherited or not, considered as isolable and that could be subject of a specific analysis. To personalize mental health interventions according to cultural identity traits, it would require adapting these interventions to meet specific workplace situations in which cultural identity traits may act as important factors. This thesis is the beginning of an answer on whether such an approach is worth of interest. This thesis examines how cultural identity traits, such as ethnicity and immigration status, affect how work is related to mental health symptoms such as psychological distress symptoms and depressive symptoms in the Canadian workforce. The limited attention paid to cultural identity traits by current models to analyze work stress, prevents a better understanding of the cultural identity traits role in the association linking work to mental health issues, while they are associated with both work and mental health. The composition of the Canadian population justifies the relevance of including cultural identity traits into a comprehensive analysis of work and mental health, as over 250 000 newcomers settle in Canada every year, with approximately 80% coming from Asia, Africa, and Latin America. Studies show that immigrants and those identified as visible minorities are more likely to end up in jobs where the working conditions are much more difficult. These two groups appear to have a higher prevalence of psychological distress symptoms and depressive symptoms. In order to address the inherent limits of the current theoretical models explaining work stress in the literature, we use in this study a multilevel analysis approach of work stress inspired by the social stress theory, and sociological approaches discussed in the United States from a micro–macro perspective, and in Europe from an agency-structure perspective. Social stress theory allows us to understand the mechanisms linking some conditions of social organization to mental health. Micro-macro and agency-structure approaches are not only concerned with dividing social reality into levels, but also try to understand the direction between levels. Our theoretical model examines three main hypotheses in which work factors with the exception of overqualification are inspired by those found in the multilevel model: 1) a direct relationship between cultural identity traits (immigrant status and ethnicity) and mental health problems (psychological distress symptoms and depressive symptoms); 2) a moderating effect of cultural identity traits on the relation between work factors (overqualification, skill utilization, decision latitude, psychological demands, physical demands, social support at work, job insecurity, worked hours, irregular work scheduling) and mental health problems; 3) a mediating role of work factors on the relation between cultural identity trait and mental health problems. The mediating effect allows us to analyze if a differential exposure to work factors based on ethnicity and immigrant status exist. The data for this study were collected from the nine cycles of the National Population Health Survey (NPHS) conducted by Statistics Canada over an 18-year period starting from 1994 and ending in 2012 after 9 cycles. Multilevel regression analyses were conducted on a sample of 6477 workers. The results of the analysis are presented in three articles representing the chapters 5 to 7 of this thesis. Results suggest that ethnicity seems to influence the relationship between work and the two analyzed symptoms. Ethnicity (visible minority versus caucasian) seems to be associated with depressive symptoms, but not with psychological distress symptoms. Among the effects of moderating variables and the effects of mediating variables tested, only one variable is proven significant. The skill utilization plays a mediating role in the relationship between ethnicity and psychological distress symptoms. There seems to be a differential exposure to work factors based on ethnicity. Compared to caucasians, visible minorities are more exposed to overqualification and less to skill utilization and decision latitude. All analyses conducted with immigration status have led to inconclusive results. Many limitations related to our research strategy (measurement of ethnicity, job quality is not taken into account, immigrant categories are not distinguished, mostly long-term immigrants, confounding variables not reflecting many realities face by the migration and integration process, etc.) call to be caution when interpreting the results of this thesis. The results of this thesis do not close debates on how cultural identity traits, such as ethnicity and immigration status affect the way work is related to mental health symptoms. However, they provide some insights into it. The results suggest that reducing risky working conditions and tackling differential exposure to work factors might provide two avenues for action against mental health problems in the Canadian workforce. Taking tangible steps on these two directions could also help lower cost related to mental health issues, which are continuously growing in Canada. One element that seems to stand out the most from this study is the need to look more closely at the issue of professional deskilling.

Utilizing the longitudinal component of the National Population Health Survey (NPHS) (1994/1995-2000/2001), designed to collect comprehensive information on the health status of the Canadian population and related socio-demographic information, differences in health status between immigrants and non-immigrants (i.e., native-born individuals) were explored. Specifically, the analysis investigated how chronic conditions influence the health of immigrants, the role of stress and mental health upon immigrant health status, and the influence and role of previously underrepresented variables such as age and arrival cohorts on foreign-born health status. The conceptual approach of this project draws upon a 'population health' perspective, which suggests that the most influential determinants of human health status are non-medical in nature, but rather can be identified as the social and economic characteristics of individuals. Analysis was completed through the use of ordinary least squares stepwise regression and logistic stepwise regression in association with descriptive stochastic methodologies. Analysis of the mental health and stress variables suggests that, contrary to what has been expressed in literature in the past, both immigrants and the native-born do not perceive stress, distress, or depression to be major problems or health concerns in their lives. Furthermore, the analysis indicated, as was expected, that older immigrants are at greater risk of developing more chronic conditions relative to younger groups, and that arrival cohorts, the period in which an immigrant entered the nation, do exert a considerable influence on the health status of the foreign-born. Surprisingly, this analysis indicates that the Healthy Immigrant Effect (HIE), which proposes that recent immigrants, regardless of country of birth, tend to be in better health than the Canadian-born population upon entering the nation, may be more apparent than real, especially when investigating mental health and stress conditions amongst the foreign-born. / Thesis / Master of Arts (MA)