RESUMO
Socioeconomic differences in morbidity and mortality, particularly across educational groups, are widening. Differential exposures to behavioural risk factors have been shown to play an important mediating role on the social inequality in chronic diseases such as heart disease, cerebrovascular disease, chronic obstructive pulmonary disease, and lung cancer. However, much less attention has been given to the potential role of interaction, where the same level of exposure to a behavioural risk factor has different effect across socioeconomic groups, creating subgroups that are more vulnerable than others. In this thesis, Paper 1 describes the unique cohort consortium which was established by pooling and harmonising prospective data from existing cohort studies in Denmark. This consortium generated a large study population with long follow-up sufficient to study power demanding questions of mechanisms underlying social inequalities in chronic disease outcomes. In Paper 2 on incidence of coronary heart disease, smoking and body mass index partially mediated the observed educational differences. This result suggested that some of the social inequality in coronary heart disease may be enhanced by differential exposure to behavioural risk factors (i.e. smoking and obesity). In Paper 3 on incidence of stroke, an observed interaction between education and smoking indicated that participants, particularly men, with low level of education may be more vulnerable to the effect of smoking than those with high level of education in terms of ischemic stroke. Finally, Paper 4 revealed that behavioural risk factors, primarily smoking, explained a considerable part of the educational differences in cause-specific mortality. Further, this paper added important knowledge about the considerable part of the mediated effect, which could be due to interaction between education and smoking. In conclusion, the research in this thesis is a practical implementation of contemporary statistical methodology, the additive hazards models, in which the potential role of behavioural risk factors can be regarded not only as mediation but also as interaction with the effect of socioeconomic position on chronic disease outcomes. The results support that two central mechanisms, differential exposure and differential vulnerability to behavioural risk factors, particularly smoking; have contributed substantially to the social inequality in chronic disease outcomes in Denmark. These mechanism are not mutually exclusive and should be regarded simultaneously. However, the findings could be non-causal associations due to, for instance, psychosocial or environmental factors. Nevertheless, research on social inequality in chronic disease outcomes should regard not only that the smoking prevalence is higher in lower socioeconomic groups (differential exposure), but also that health consequences of being a smoker seem to be worse in these subgroups (differential vulnerability).
Assuntos
Doença Crônica/epidemiologia , Classe Social , Doenças Cardiovasculares/mortalidade , Doença Crônica/mortalidade , Estudos de Coortes , Dinamarca , Escolaridade , Humanos , Incidência , Prevalência , Estudos Prospectivos , Fatores de Risco , Fumar/epidemiologia , Fatores Socioeconômicos , Acidente Vascular Cerebral/mortalidadeRESUMO
BACKGROUND: Differential exposures to behavioral risk factors have been shown to play an important mediating role on the education-mortality relation. However, little is known about the extent to which educational attainment interacts with health behavior, possibly through differential vulnerability. METHODS: In a cohort study of 76,294 participants 30 to 70 years of age, we estimated educational differences in cause-specific mortality from 1980 through 2009 and the mediating role of behavioral risk factors (smoking, alcohol intake, physical activity, and body mass index). With the use of marginal structural models and three-way effect decomposition, we simultaneously regarded the behavioral risk factors as intermediates and clarified the role of their interaction with educational exposure. RESULTS: Rate differences in mortality comparing participants with low to high education were 1,277 (95% confidence interval = 1,062 to 1,492) per 100,000 person-years for men and 746 (598 to 894) per 100,000 person-years for women. Smoking was the strongest mediator for cardiovascular disease, cancer, and respiratory disease mortality when conditioning on sex, age, and cohort. The proportion mediated through smoking was most pronounced in cancer mortality as a combination of the pure indirect effect, owing to differential exposure (men, 42% [25% to 75%]; women, 36% [17% to 74%]) and the mediated interactive effect, owing to differential vulnerability (men, 18% [2% to 35%], women, 26% [8% to 50%]). The mediating effects through body mass index, alcohol intake, or physical activity were partial and varied for the causes of deaths. CONCLUSION: Differential exposure and vulnerability should be addressed simultaneously, as these mechanisms are not mutually exclusive and may operate at the same time.
Assuntos
Doenças Cardiovasculares/mortalidade , Causas de Morte , Escolaridade , Disparidades nos Níveis de Saúde , Doenças Respiratórias/mortalidade , Adulto , Distribuição por Idade , Idoso , Consumo de Bebidas Alcoólicas/epidemiologia , Doenças Cardiovasculares/diagnóstico , Estudos de Coortes , Intervalos de Confiança , Dinamarca , Feminino , Comportamentos Relacionados com a Saúde , Humanos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Neoplasias/epidemiologia , Estudos Prospectivos , Doenças Respiratórias/diagnóstico , Medição de Risco , Distribuição por Sexo , Fumar/epidemiologia , Taxa de Sobrevida , Populações VulneráveisRESUMO
The Social Inequality in Cancer (SIC) cohort study was established to determine pathways through which socioeconomic position affects morbidity and mortality, in particular common subtypes of cancer. Data from seven well-established cohort studies from Denmark were pooled. Combining these cohorts provided a unique opportunity to generate a large study population with long follow-up and sufficient statistical power to develop and apply new methods for quantification of the two basic mechanisms underlying social inequalities in cancer-mediation and interaction. The SIC cohort included 83 006 participants aged 20-98 years at baseline. A wide range of behavioural and biological risk factors such as smoking, physical inactivity, alcohol intake, hormone replacement therapy, body mass index, blood pressure and serum cholesterol were assessed by self-administered questionnaires, physical examinations and blood samples. All participants were followed up in nationwide demographic and healthcare registries. For those interested in collaboration, further details can be obtained by contacting the Steering Committee at the Department of Public Health, University of Copenhagen, at inan@sund.ku.dk.
Assuntos
Disparidades nos Níveis de Saúde , Neoplasias/epidemiologia , Classe Social , Adulto , Idoso , Idoso de 80 Anos ou mais , Consumo de Bebidas Alcoólicas/epidemiologia , Estudos de Coortes , Dinamarca/epidemiologia , Escolaridade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fatores de Risco , Comportamento Sedentário , Fumar/epidemiologia , Determinantes Sociais da Saúde , Fatores Socioeconômicos , Adulto JovemRESUMO
Educational-related gradients in coronary heart disease (CHD) and mediation by behavioral risk factors are plausible given previous research; however this has not been comprehensively addressed in absolute measures. Questionnaire data on health behavior of 69,513 participants, 52 % women, from seven Danish cohort studies were linked to registry data on education and incidence of CHD. Mediation by smoking, low physical activity, and body mass index (BMI) on the association between education and CHD were estimated by applying newly proposed methods for mediation based on the additive hazards model, and compared with results from the Cox proportional hazards model. Short (vs. long) education was associated with 277 (95 % CI: 219, 336) additional cases of CHD per 100,000 person-years at risk among women, and 461 (95 % CI: 368, 555) additional cases among men. Of these additional cases 17 (95 % CI: 12, 22) for women and 37 (95 % CI: 28, 46) for men could be ascribed to the pathway through smoking. Further, 39 (95 % CI: 30, 49) cases for women and 94 (95 % CI: 79, 110) cases for men could be ascribed to the pathway through BMI. The effects of low physical activity were negligible. Using contemporary methods, the additive hazards model, for mediation we indicated the absolute numbers of CHD cases prevented when modifying smoking and BMI. This study confirms previous claims based on the Cox proportional hazards model that behavioral risk factors partially mediates the effect of education on CHD, and the results seems not to be particularly model dependent.
Assuntos
Escolaridade , Comportamentos Relacionados com a Saúde , Índice de Massa Corporal , Estudos de Coortes , Doença das Coronárias/epidemiologia , Doença das Coronárias/prevenção & controle , Dinamarca/epidemiologia , Exercício Físico , Humanos , Estilo de Vida , Masculino , Modelos de Riscos Proporcionais , Sistema de Registros , Fatores de Risco , Fatores Sexuais , Fumar/efeitos adversos , Fumar/epidemiologia , Inquéritos e QuestionáriosRESUMO
PURPOSE: Indicators such as country of birth and language spoken at home have been used as proxy measures for ethnic background, but the validity of these indicators in surveys among school children remains unclear. This study aimed at comparing item response and student-parent agreement on four questions about country of birth and language spoken at home in three European countries. METHODS: We analyzed data from the Health Behaviour in School-aged Children (HBSC) Child-Parent Validation Study 2005, including 486 matched student-parent pairs from Denmark, Hungary, and Scotland. Selected items from the internationally standardized HBSC questionnaire were completed by 11-year-old students and their parents. We examined item response and student-parent agreement on the four HBSC Ethnic Background Indicators: the student's country of birth, mother's country of birth, father's country of birth, and language usually spoken at home. RESULTS: All item response rates were high for both students (>92%) and parents (>96%). The percent student-parent agreement was high on all four items (>97%). The strength of agreement ranged from good to excellent for all items indicated by the kappa value (between .60 and 1.00). Results were robust across countries. CONCLUSIONS: Our findings suggest that students as young as 11 years are able to provide valid responses to four simple questions about country of birth and language spoken at home. The four HBSC Ethnic Background Indicators can be useful in epidemiologic studies on identification of subgroups that may receive unequal prevention services or in assessment of how risk factors, symptoms, and diseases may differ by ethnic background among school children.
Assuntos
Comportamento Infantil/etnologia , Etnicidade/estatística & dados numéricos , Relações Pais-Filho/etnologia , Pais/psicologia , Inquéritos e Questionários/normas , Adulto , Criança , Comportamento Infantil/psicologia , Estudos Transversais , Coleta de Dados , Dinamarca/epidemiologia , Feminino , Comportamentos Relacionados com a Saúde , Humanos , Hungria/epidemiologia , Masculino , Reprodutibilidade dos Testes , Escócia/epidemiologiaRESUMO
OBJECTIVE: To investigate whether exposure to fast-food outlets and supermarkets is socio-economically patterned in the city of Copenhagen. DESIGN: The study was based on a cross-sectional multivariate approach to examine the association between the number of fast-food outlets and supermarkets and neighbourhood-level socio-economic indicators. Food business addresses were obtained from commercial and public business locators and geocoded using a geographic information system for all neighbourhoods in the city of Copenhagen (n 400). The regression of counts of fast-food outlets and supermarkets v. indicators of socio-economic status (percentage of recent immigrants, percentage without a high-school diploma, percentage of the population under 35 years of age and average household income in Euros) was performed using negative binomial analysis. SETTING: Copenhagen, Denmark. SUBJECTS: The unit of analysis was neighbourhood (n 400). RESULTS: In the fully adjusted models, income was not a significant predictor for supermarket exposure. However, neighbourhoods with low and mid-low income were associated with significantly fewer fast-food outlets. Using backwise deletion from the fully adjusted models, low income remained significantly associated with fast-food outlet exposure (rate ratio = 0·66-0·80) in the final model. CONCLUSIONS: In the city of Copenhagen, there was no evidence of spatial patterning of supermarkets by income. However, we detected a trend in the exposure to fast-food outlets, such that neighbourhoods in the lowest income quartile had fewer fast-food outlets than higher-income neighbourhoods. These findings have similarities with studies conducted in the UK, but not in the USA. The results suggest there may be socio-economic factors other than income associated with food exposure in Europe.