No description available.

Objective: This study attempts to estimate the proportion of incident cases of bladder cancer in Ontario, Canada that is due to exposure to occupational carcinogens. Methods: The population attributable risk approach is used to estimate the proportion of bladder cancer in Ontario that is due to occupation. Risk ratios were obtained from a review of epidemiologic literature using a priori inclusion and exclusion criteria. Summary risk estimates for each bladder carcinogen included were calculated using RevMan 4.2. The CAREX Canada database provided Ontario-specific estimates of the proportion of workers exposed to bladder carcinogens. Results: In Ontario, the proportion of bladder cancer due to occupational exposure is approximately 5.6% (95% CI 0.2% to 14%). Based on the incident number of bladder cancer cases in 2001 in Ontario, it is estimated that approximately 52 new cases of bladder cancer were due to occupational exposure to polycyclic aromatic hydrocarbons (PAHs), diesel exhaust, aromatic amines and 2-naphthylamine. An alternate interpretation is if these occupational exposures were eliminated, 52 cases of bladder cancer per year in Ontario alone could be avoided. Conclusion and Recommendations: The current study advances our knowledge of the extent to which specific occupational bladder carcinogens contribute to the overall bladder cancer burden in Ontario. The current study highlights the utility of the CAREX Canada database in advancing current knowledge on the burden of occupational cancer in Ontario. The methods used to estimate the proportion of bladder cancer attributable to occupational exposure in Ontario may be replicated to estimate the proportion of cancer in Ontario that is due to occupational exposure. / Thesis (Master, Community Health & Epidemiology) -- Queen's University, 2008-08-29 20:08:46.713

Campylobacter is currently the most common cause of acute bacterial diarrhoea in Australia among all the notified enteric pathogens with more than 15,000 cases each year. The incidence of notified campylobacteriosis has steadily increased during the past 15 years from 67.0/100,000 population in 1991 to 121.4/100,000 in 2005, though the factors contributing to this increase had not been studied. Adjusting for under-reporting there are, at this point in time, an estimated 225,000 infections occurring each year in Australia, most of which are sporadic in nature. Much of our knowledge in Australia about risk factors for sporadic disease has been based on overseas literature. Prior to the studies undertaken in this thesis, the epidemiology of Campylobacter infection had not been thoroughly studied in Australia, nor had there been any national studies examining risk factors for locally-acquired infection. The broad aim of this thesis was to examine in depth the descriptive epidemiology of Campylobacter infection in Australia, explore the reasons for the sustained increase in incidence of infection and to identify the major risk factors for locally acquired infection using a multi-centre case-control study design. The descriptive study of the epidemiology of campylobacteriosis in Australia was based on Australian notifiable disease surveillance data collected over a 15-year period between 1991 and 2005. This study described the key epidemiological characteristics of this disease in Australia and identified some significant differences in incidence trends across states and territories and among different age groups which had not been previously reported. The study identified gaps in our knowledge of this disease in Australia and made recommendations for future research including the investigation of factors associated with the decline in incidence of infection among children aged  4 years and further studies to identify age and sex-specific risk factors for infection. The issue of seasonality, transmission routes and infection was addressed and areas for further research were specified including longitudinal studies at a regional level that incorporate a comparison of human, animal and environmental genotypes. This study also provided strong compelling evidence to support the hypothesis that the increase in notification rates in Australia during this period represented a real increase in the incidence of infection and that the main driving force behind this rise has been the ongoing increase in chicken consumption among the Australian public. The multi-centre case-control study, involving 1,714 participants  5 years of age, identified the major foodborne and non-foodborne risk factors for Campylobacter infection among the general population in Australia. This study confirmed that chicken meat is a major source of sporadic infection in this country and is responsible for almost one-third of all cases that occur in the Australian community each year. Other independent risk factors for sporadic infection in Australia included consumption of offal and ownership of domestic dogs or chickens aged  6 months. The Nagelkerke R² value of 16% for the final multivariable model indicated a considerable proportion of our case-patients had unexplained risk factors. The combined population attributable risk (PAR) estimate for the independent foodborne risk factors in this study was 31%, which is considerably less than the 75% to 80% of cases in the general population which are thought to be caused through foodborne transmission. Possible explanations for these results include the likelihood that a proportion of foodborne transmission in Australia occurs through food vehicles other than chicken due to cross-contamination from raw products, and the likelihood that much of the population attributable risk that is unaccountered for, may in fact be due to inherent limitations of study design resulting in systematic errors (information bias) and possibly reduced estimates of effect. The burden of illness among the general population in Australia attributable to different independent risk factors was estimated using a novel method developed specifically for this study. Briefly, community incidence data was coupled with PAR data from the case-control study and simulation techniques were used to: (i) estimate the number of infections attributable to specific risk factors, and (ii) derive credible intervals for these estimates by modeling the uncertainty in each variable component. This model of using case-control data in conjunction with pre-existing surveillance data provides researchers with a simple but robust tool for conducting source attribution studies on enteric pathogens. In conclusion, the studies undertaken in this thesis have made important contributions to our understanding of the epidemiology of sporadic Campylobacter infection in Australia.

No description available.

This project discusses some of the methodologies developed over the years to estimate attributable risk among exposed persons and the attributable risk in the entire population (also called Etiologic Fraction). It provides a general framework for estimating attributable risk among the exposed (denoted lambda_e). By making use of the recent observation that the two measures of attributable risk can be linked through the prevalence of the risk factor among the cases (denoted V_x), an estimate of population attributable risk (denoted lambda) for matched case-control studies is determined. Using the methodology developed recently by Kuritz and Landis (1987), this project provides explicit formulas for estimating the attributable risk among the exposed and the population attributable risk, and their large sample variances. This has been done both in situations where exactly R controls have been matched to a case and for a variable number of controls per case. The methodologies are illustrated with data from some case-control studies reported in the literature. Asymptotic relative efficiencies of different matching designs computed in terms of the costs of gathering cases and controls, are presented, together with some recommendations on what design is considered optimal. / Thesis / Master of Science (MSc)

Orientador: Ricardo Cordeiro / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-10T04:52:01Z (GMT). No. of bitstreams: 1 Dias_Adriano_D.pdf: 1797501 bytes, checksum: effde01c2013242dc07df67485644926 (MD5) Previous issue date: 2007 / Resumo: O objetivo deste estudo foi verificar se a exposição ocupacional ao ruído é um fator de risco relevante para acidentes do trabalho. O resultado desta pesquisa foram três artigos científicos. O primeiro teve por objetivo promover uma revisão da literatura nacional de acesso eletrônico livre divulgada pelo SciELO Brasil desde o início de suas atividades até março de 2006, acerca da exposição ocupacional ao ruído e de seus efeitos sobre a saúde dos trabalhadores. Dos 50 artigos obtidos na revisão apenas 19 deles tratavam do ruído de origem ocupacional como exposição possivelmente causadora de algum dano na saúde de trabalhadores, que foram analisados no tocante ao seu delineamento, objetivos e resultados. O segundo artigo resultou de um estudo caso-controle de base hospitalar, desenvolvido no município de Piracicaba, estado de São Paulo, Brasil, com 600 casos e 822 controles, todos trabalhadores, que estimou o risco de sofrer acidente do trabalho cerca de 2 vezes maior entre trabalhadores expostos ao ruído. O terceiro artigo estimou a fração de acidentes do trabalho atribuível à exposição ocupacional ao ruído, a partir do estudo caso-controle desenvolvido no segundo estudo. e nele obtiveram-se os odds ratio de acidentes do trabalho relacionando trabalhadores expostos ao ruído em três níveis, bem como da prevalência destas exposições. Com estes resultados estimou-se a fração atribuível como 0,3041 (IC95% = 0,2341-0,3676), o que equivale a dizer que mais de 30% dos acidentes do trabalho ocorridos nesta localidade são estatisticamente associados à exposição ocupacional ao ruído. Discute-se a causalidade desta relação e suas implicações para a prevenção dos acidentes do trabalho / Abstract: This study aimed at assessing whether occupational noise exposure is a significant risk factor for work-related accidents. The investigation yielded three scientific papers. The first consisted of a review of the national literature on the effects of occupational noise on the health of workers available for free-access at SciELO Brasil from its beginning through March/2006. Of the 50 articles obtained, only 19 reported exposure to occupational noise as a probable cause of health damage among workers, and were analyzed in terms of design, objective and results. The second paper resulted from a hospital-based case-control study conducted in the municipal district of Piracicaba, state of São Paulo-Brazil that included 600 cases and 822 controls (all workers). The risk of work-related accidents was found to be two-fold higher in workers exposed to noise. The third article reported the fraction of work-related accidents attributable to occupational noise exposure, based on the case-control study mentioned above. The odds ratio of work-related accidents was obtained by relating workers exposed to noise with three noise levels, and the prevalence of such exposures was determined. Thus, the attributable fraction was estimated to be 0,3041 (IC95% = 0,2341-0,3676), i.e., over 30% of the work-related accidents that occurred in the study area are statistically associated with occupational noise exposure. The causes of this relationship are discussed, as well as its implications in the prevention of work-relatedaccidents / Doutorado / Saude Coletiva / Doutor em Saude Coletiva

Le risque attribuable est un outil épidémiologique apparu dans les années 1950 aujourd’hui encore assez peu utilisé. Il permet d’estimer la proportion de cas d’une maladie potentiellement évitable par suppression ou réduction de l’exposition d’une population à un facteur de risque. Son principal intérêt réside dans la prise en compte concomitante de l’ampleur d’effet du facteur de risque et de la distribution de ce facteur au sein de la population. Après une présentation des caractéristiques essentielles du risque attribuable et des principes de son estimation à partir d’une étude cas-témoins, nous proposons un cadre conceptuel qui permet d’estimer l’impact d’une intervention de santé publique dans une nouvelle population dont l’exposition à certains facteurs de risque diffère de celle observée dans la population d’étude. Une décomposition du risque attribuable permet alors de prendre en compte l’action combinée, ou synergie, des facteurs de risque dans la survenue de la maladie. Parce qu’il donne une dimension populationnelle à l’estimation de l’effet d’une variable, le risque attribuable est particulièrement intéressant pour quantifier l’importance relative des différentes variables explicatives d’un modèle de régression. La question de l’importance relative des biomarqueurs classiques et de ceux issus des technologies à haut débit dans les modèles diagnostiques est actuellement centrale pour établir les apports respectifs de ces deux niveaux d’information. À partir de simulations, nous montrons comment l’apport des nouvelles technologies, quantifié en termes de risque attribuable, peut être faussé par l’utilisation de méthodologies inadaptées / The attributable risk is an epidemiologic tool that dates back to the fifties but is still relatively seldom used. It estimates the proportion of cases of a given disease that could be avoided if the exposure to a specific risk factor was removed or reduced. Its major interest is that it combines the magnitude of the effect of the risk factor to the distribution of this factor within the population. After a review of the attributable risk main features and the principles of its estimation from case-control studies data, we propose a conceptual framework that allows estimating the impact of a public health intervention in a new population with different exposure to certain risk factors than those observed in the study population. To reach this goal, we used a splitting of the attributable risk that takes into account the combined action –or synergy– of the risk factors on the occurrence of the disease. Because the attributable risk allows estimating the effect of a variable at the population level, it is particularly interesting to quantify the relative importance of the covariates of a regression model. In diagnostic models, the estimation of the relative importance of classic biomarkers and biomarkers obtained from high-throughput technologies is currently crucial in establishing the contribution of each of these two levels of information. Using simulations we have demonstrated the way the role of high-throughput-technologies –quantified in terms of attributable risk– may be wrongly assessed through the use of unsuitable methodology

Madagascar fait partie de la zone de haute endémicité pour l‟hépatite B dont le profil de circulation varie selon la ruralité de la zone d‟habitation. De par son insularité et les origines de ses peuplements, nous avons supposé que ce profil de circulation du VHB était dû à la variabilité du VHB et à l‟hétérogénéité du profil de transmission. Ce projet de thèse a pour objectif principal de déterminer les facteurs épidémiologiques et moléculaires influençant la dynamique de transmission et l‟évolution vers les complications de l‟infection par le virus de l‟hépatite B à Madagascar. Résultats : la séroprévalence globale pondérée en Ag HBs est de 6,9% avec des variations allant de 0% à 26% selon les zones géographiques considérées. La prévalence augmente en s‟éloignant des grandes villes et des principales routes nationales les reliant et chez les individus à faible statutsocio-économique. L‟étude du flux génétique des souches virales de l‟hépatite B montre que les zones les plus reculées représentent un réservoir pour la dissémination du virus. L‟infection par le virus de l‟hépatite B est responsable de 31% des maladies hépatiques chroniques rencontrées dans les services hospitaliers investigués à Antananarivo. L‟introduction du VHB s‟est probablement faite au cours du XIXème siècle. Sa propagation à l‟intérieur du pays a pris une allure exponentielle durant les années 80s probablement durant les épidémies de paludisme et suite à des réutilisations des matériels d‟injections. Conclusion : Les résultats de ces différents travaux nous ont permis de plaider pour une politique de lutte visant en particulier les zones très reculées de l‟île où la prévalence en AgHBs est la plus importante. / Madagascar is part of endemic region of HBV. Distribution is different in rural and urban area. The historic of human settlement and its insularity might impact distribution and molecular characteristic of HBV in Madagascar, we then supposed that difference observed in distribution and prevalence of HBV were due to viral variability and different pattern of viral transmission. Therefore, the main objective of this thesis was to determine molecular and epidemiological pattern that may influence dynamic transmission and complications of infection. Results: weighted prevalence of HBsAg was 6.9%. It varied from 3% to 26% according to area of sampling. Populations with a low socio-economic status and those living in rural areashad a significantly higher seroprevalence of HBsAg. Gene flow study showed rural area remain important in virus diffusion.HBV infection was found to be responsible of 31% of chronic liver disease encountered in the main public hospital in the capital of the country. Because of its recent emergence, its introduction dated from XIX century during colonization period. Its expansion during 1980s might be due to use of unsafe injection material mainly during malaria epidemic. Conclusion: The result of these work allowed us to advocate for a policy of struggle, in particular in the very remote areas of the island where the HBsAg prevalence is the most important and where care and preventive measures such as vaccinations are scarce.

Objective: The Affordable Care Act (ACA) has influenced increasing interests in population health and population health outcomes. The purpose of this study was to exemplify the importance of using existing vital statistics data for understanding and monitoring health outcomes and consequentially health disparities at the population level. Data from birth records for two geographic regions from 2009-2014 were compared; low birth weight (LBW) and preterm delivery (PD) were used as surrogates for population health outcomes. Methods: A population-based, multi-year, cross-sectional study design using a pooled dataset of birth records from Tennessee (TN) was the framework for the analyses. A sub-population from North East TN (NE TN) was compared to TN. Logistic regression was used to estimate odds ratios. Attributable risks were calculated to translate the findings from conditional associations to population-level associations to help inform public health policy decision-making. Results: Using birth records (vital statistics), we demonstrated that the period prevalence of cigarette smoking before and during pregnancy remained unchanged with approximately one in three women in NE TN (from 37% in 2009 to 32% in 2014) and one in five women in TN (from 23% in 2009 to 20% in 2014) reporting smoking pre-pregnancy. Multivariate analyses demonstrated that mothers who were at each end of the age spectrum, of very low household income level and reported cigarette smoking pre-pregnancy or during pregnancy had increased risk of a LBW or PD infant. During the years of observation, 39 to 50% of the total incidence of LBW in the group of women who smoked cigarettes prior to pregnancy was attributable to smoking cigarettes. Conclusions: Existing data, such as vital statistics data, should be used routinely to identify geographic areas for which programs or policies can be implemented to reach large portions of populations. Reducing prenatal smoking, for example, has the potential to reduce a large fraction of adverse birth outcomes such as LBW and PD. For the geographic area we evaluated, 39 to 50% of LBW could be prevented by devising population-based smoking cessation programs or policies for women of child-bearing age. With recent emphasis on prevention and well-baby care in the ACA, there is potential to increase attention to this problem, implement evidence-based prevention programs and monitor program effectiveness with existing birth record data. Following this model, we can attain population health goals and address health disparities.

In a large population-based study among adults in northern Europe the relation between occupational exposure and new-onset asthma was studied. The study comprised 13 284 subjects born between 1945 and 1973, who answered a questionnaire 19891992 and again 19992001. Asthma was defined as Asthma diagnosed by a physician with reported year of diagnose. Hazard ratios (HR), for new-onset adult asthma during 19802000, were calculated using a modified job-exposure matrix as well as high-risk occupations in Cox regression models. The analyses were made separately for men and women and were also stratified for atopy. During the observation period there were 429 subjects with new-onset asthma with an asthma incidence of 1.3 cases per 1000 person-years for men and 2.4 for women. A significant increase in new-onset asthma was seen for men exposed to plant-associated antigens (HR 3.6; 95% CI [confidence interval] 1.49.0), epoxy (HR 2.4; 95% CI 1.34.5), diisocyanates (HR 2.1; 95% CI 1.23.7) and accidental peak exposures to irritants (HR 2.4; 95% CI 1.34.7). Both men and women exposed to cleaning agents had an increased asthma risk. When stratifying for atopy an increased asthma risk were seen in non-atopic men exposed to acrylates (HR 3.3; 95% CI 1.47.5), epoxy compounds (HR 3.6; 95% CI 1.67.9), diisocyanates and accidental peak exposures to irritants (HR 3.0; 95% CI 1.27.2). Population attributable risk for occupational asthma was 14% for men and 7% for women. This population-based study showed that men exposed to epoxy, diisocyanates and acrylates had an increased risk of new-onset asthma. Non-atopics seemed to be at higher risk than atopics, except for exposure to high molecular weight agents. Increased asthma risks among cleaners, spray painters, plumbers, and hairdressers were confirmed.