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‣ Trends in aortic aneurysm- and dissection-related mortality in the state of Sao Paulo, Brazil, 1985-2009: multiple-cause-of-death analysis

Santo, Augusto Hasiak; Puech-Leao, Pedro; Krutman, Mariana
Fonte: BIOMED CENTRAL LTD; LONDON Publicador: BIOMED CENTRAL LTD; LONDON
Tipo: Artigo de Revista Científica
Português
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Background: Aortic aneurysm and dissection are important causes of death in older people. Ruptured aneurysms show catastrophic fatality rates reaching near 80%. Few population-based mortality studies have been published in the world and none in Brazil. The objective of the present study was to use multiple-cause-of-death methodology in the analysis of mortality trends related to aortic aneurysm and dissection in the state of Sao Paulo, between 1985 and 2009. Methods: We analyzed mortality data from the Sao Paulo State Data Analysis System, selecting all death certificates on which aortic aneurysm and dissection were listed as a cause-of-death. The variables sex, age, season of the year, and underlying, associated or total mentions of causes of death were studied using standardized mortality rates, proportions and historical trends. Statistical analyses were performed by chi-square goodness-of-fit and H Kruskal-Wallis tests, and variance analysis. The joinpoint regression model was used to evaluate changes in age-standardized rates trends. A p value less than 0.05 was regarded as significant. Results: Over a 25-year period, there were 42,615 deaths related to aortic aneurysm and dissection, of which 36,088 (84.7%) were identified as underlying cause and 6...

‣ Trends in aortic aneurysm- and dissection-related mortality in the state of São Paulo, Brazil, 1985–2009: multiple-cause-of-death analysis

Santo, Augusto Hasiak; Leao, Pedro Puech; Krutman, Mariana 
Fonte: London Publicador: London
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
157.63753%
Background: Aortic aneurysm and dissection are important causes of death in older people. Ruptured aneurysms show catastrophic fatality rates reaching near 80%. Few population-based mortality studies have been published in the world and none in Brazil. The objective of the present study was to use multiple-cause-of-death methodology in the analysis of mortality trends related to aortic aneurysm and dissection in the state of Sao Paulo, between 1985 and 2009. Methods: We analyzed mortality data from the Sao Paulo State Data Analysis System, selecting all death certificates on which aortic aneurysm and dissection were listed as a cause-of-death. The variables sex, age, season of the year, and underlying, associated or total mentions of causes of death were studied using standardized mortality rates, proportions and historical trends. Statistical analyses were performed by chi-square goodness-of-fit and H Kruskal-Wallis tests, and variance analysis. The joinpoint regression model was used to evaluate changes in age-standardized rates trends. A p value less than 0.05 was regarded as significant. Results: Over a 25-year period, there were 42,615 deaths related to aortic aneurysm and dissection, of which 36,088 (84.7%) were identified as underlying cause and 6...

‣ Trends in aortic aneurysm- and dissection-related mortality in the state of São Paulo, Brazil, 1985–2009: multiple-cause-of-death analysis

Santo, Augusto H; Puech-Leão, Pedro; Krutman, Mariana
Fonte: Biblioteca Digital da Produção Intelectual da USP Publicador: Biblioteca Digital da Produção Intelectual da USP
Tipo: Artigo de Revista Científica
Português
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Abstract Background Aortic aneurysm and dissection are important causes of death in older people. Ruptured aneurysms show catastrophic fatality rates reaching near 80%. Few population-based mortality studies have been published in the world and none in Brazil. The objective of the present study was to use multiple-cause-of-death methodology in the analysis of mortality trends related to aortic aneurysm and dissection in the state of Sao Paulo, between 1985 and 2009. Methods We analyzed mortality data from the Sao Paulo State Data Analysis System, selecting all death certificates on which aortic aneurysm and dissection were listed as a cause-of-death. The variables sex, age, season of the year, and underlying, associated or total mentions of causes of death were studied using standardized mortality rates, proportions and historical trends. Statistical analyses were performed by chi-square goodness-of-fit and H Kruskal-Wallis tests, and variance analysis. The joinpoint regression model was used to evaluate changes in age-standardized rates trends. A p value less than 0.05 was regarded as significant. Results Over a 25-year period...

‣ Trends in aortic aneurysm- and dissection-related mortality in the state of São Paulo, Brazil, 1985–2009: multiple-cause-of-death analysis

Santo, Augusto H; Puech-Leão, Pedro; Krutman, Mariana
Fonte: Biblioteca Digital da Produção Intelectual da USP Publicador: Biblioteca Digital da Produção Intelectual da USP
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
157.63753%
Abstract Background Aortic aneurysm and dissection are important causes of death in older people. Ruptured aneurysms show catastrophic fatality rates reaching near 80%. Few population-based mortality studies have been published in the world and none in Brazil. The objective of the present study was to use multiple-cause-of-death methodology in the analysis of mortality trends related to aortic aneurysm and dissection in the state of Sao Paulo, between 1985 and 2009. Methods We analyzed mortality data from the Sao Paulo State Data Analysis System, selecting all death certificates on which aortic aneurysm and dissection were listed as a cause-of-death. The variables sex, age, season of the year, and underlying, associated or total mentions of causes of death were studied using standardized mortality rates, proportions and historical trends. Statistical analyses were performed by chi-square goodness-of-fit and H Kruskal-Wallis tests, and variance analysis. The joinpoint regression model was used to evaluate changes in age-standardized rates trends. A p value less than 0.05 was regarded as significant. Results Over a 25-year period...

‣ Promoção da saúde cardiovascular a partir da representação de adolescentes sobre hábitos alimentares e prática de atividade física; Promoting cardiovascular health through the representation of adolescents on eating habits and physical activity practice

Ianeta, Luciana Maria Oliveira Fonseca
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 31/07/2007 Português
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INTRODUÇÃO: Estudos epidemiológicos demonstram que as doenças cardiovasculares e suas complicações estão associadas ao estilo de vida das pessoas. Há evidências de que o processo aterosclerótico se inicia na infância, e que sua prevenção pode ser mais efetiva se iniciada precocemente, com ações de educação em saúde que visem a promover a prática regular de atividade física e a mudança de hábitos alimentares. OBJETIVOS: Observação das representações dos adolescentes sobre hábitos alimentares e práticas de atividade física no contexto da promoção da saúde cardiovascular. Verificação d a exeqüibilidade das técnicas de ensino-aprendizagem baseadas em Paulo Freire, Pichon-Rivière, Prochaska e Di Clemente na reflexão com os adolescentes sobre a prevenção primária dos fatores de risco relacionados com essas representações. Testar a hipótese de que a presença da doença cardiovascular nos familiares têm influência nas representações observadas. MÉTODOS: Alunos da sétima série de uma escola pública de São Paulo foram levantados por meio de questionário epidemiológico para avaliar os riscos associados ao estilo de vida. Dois grupos diferentes de alunos, selecionados de acordo com a presença de doença cardiovascular nos pais...

‣ Regulamentação dos planos de saúde e risco moral : aplicação da regressão quantílica para dados de contagem

Godoy, Márcia Regina
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Tese de Doutorado Formato: application/pdf
Português
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O setor de saúde suplementar brasileiro operou desde os anos de 1940 sem regulação. Em 1998, o governo estabeleceu a regulação deste setor. Na regulamentação das atividades foram estabelecidas a ilimitação do número de consultas médicas, proibição de seleção de risco, entre outras medidas. O objetivo deste trabalho é investigar se a regulação resultou em aumento do número de consultas médicas por parte dos subscritores de planos de saúde, ou seja se ocorreu aumento do risco moral ex-post. Além disto, analisar alterações nos determinantes da demanda por posse de plano de saúde antes e após a regulação visando encontrar indícios de seleção adversa. Para isto, foram utilizados quatro métodos econométricos: regressão de Poisson, regressão binomial negativa e regressão quantílica de dados de contagem e um modelo Probit. O estimador de diferenças-em-diferenças foi utilizado para estimar o impacto da regulação sobre o número de consultas médicas. O modelo de regressão Probit foi utilizado para analisar os determinantes da demanda por posse de plano de saúde. Os dados utilizados provêm da Pesquisa Nacional de Amostra de Domicílios de 1998 (antes da regulação) e 2003 (depois da regulamentação). Os dados foram divididos por sexo e também pelo perfil epidemiológico...

‣ Associação entre sintomas depressivos e funcionamento social em cuidados primários de saúde; Association of depressive symptoms and social functioning in primary care service, Brazil

Fleck, Marcelo Pio de Almeida; Lima, Ana Flavia Barros da Silva; Louzada, Sérgio Noll; Schestatsky, Gustavo; Henriques, Alexandre Annes; Borges, Vivian Roxo; Camey, Suzi Alves; Grupo LIDO (Longitudinal Investigation of Depression Outcomes)
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
Português
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Objetivo: Os transtornos depressivos constituem um problema de saúde pública devido a sua alta prevalência e impacto psicossocial. Pacientes deprimidos são freqüentadores assíduos de serviços de atendimento primário, porém, muitas vezes, não são diagnosticados como tais. O objetivo do estudo é avaliar a associação entre sintomas depressivos e funcionamento social numa amostra de pacientes que procuraram um serviço de cuidados primários em uma capital brasileira. Métodos: Foram avaliados 2.201 usuários de serviços de cuidados de saúde primários de Porto Alegre quanto à saúde física e emocional. Foi aplicado questionário em entrevista única, com duas questões genéricas de avaliação de qualidade de vida do World Health Organization Quality of Life (WHOQOL-Breve), mais itens do Medical Outcomes Study Short-Forms 12 (SF-12) e MHI 5 (MHI-5), do Centers for Epidemiologic Studies – Depression (CES-D), além de outras questões referentes a busca de atendimento médico e faltas ao trabalho. Foram realizados testes de Kruska- Wallis e de comparações múltiplas de Tambane. Resultados: Dos indivíduos estudados, 79,5% eram do sexo feminino, com média de idade de 40 anos. A intensidade da sintomatologia depressiva medida pelo CES-D foi de 20...

‣ Transmissão vertical de hepatite em gestantes no CAISM Campinas= : HBV mother to child transmission at CAISM UNICAMP; HBV mother to child transmission at CAISM UNICAMP

Elaine Cristina Cândido
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 30/08/2013 Português
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Objetivos: avaliar a transmissão vertical (TV) em gestantes portadoras de hepatite B crônica, em um serviço universitário. Sujeitos e Método: foram analisadas as sorologias para hepatite B de todas as gestantes atendidas no serviço entre 2000 e 2005, identificando-se as HbsAg +; nessas foi realizado levantamento de prontuários, avaliando a presença do marcador de replicação viral (HbeAg positivo), imunoprofilaxia neonatal e taxa de TV. Análise de dados: foi avaliada a proporção de casos com HbsAg+ e nessas a presença do HbeAg. Para as portadoras de hepatite B, analisaram-se características clínicas e epidemiológicas através de frequências simples e a presença de TV. Resultados: entre 2000 e 2005 foram rastreadas para hepatite B no CAISM 5638 mulheres; dessas 28 (0,5%) apresentavam HbsAg+, definindo-se como portadoras crônicas. Não se encontrou nenhuma com replicação viral (HbeAg+). A idade média foi de 25 anos, com escolaridade média de sete anos, sendo 57% de brancas. O número de gestações médio foi de dois, sendo 52% de nulíparas. A categoria de exposição foi ignorada em 20; em quatro a via foi a sexual, em duas por TV e em duas por uso de drogas. A média de Idade gestacional ao parto foi de 38 semanas...

‣ Epidemiology of basal cell carcinomas and squamous cell carcinomas in a Department of Dermatology: a 5 year review

Andrade,Pedro; Brites,Maria Manuel; Vieira,Ricardo; Mariano,Angelina; Reis,José Pedro; Tellechea,Oscar; Figueiredo,Américo
Fonte: Sociedade Brasileira de Dermatologia Publicador: Sociedade Brasileira de Dermatologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2012 Português
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BACKGROUND: Non-melanoma skin cancer, a common designation for both basal cell carcinomas and squamous cell carcinomas, is the most frequent malignant skin neoplasm. OBJECTIVE: Epidemiologic characterization of the population with Non-melanoma skin cancer. METHODS: Retrospective analysis of all patients diagnosed with Non-melanoma skin cancer based on histopathologic analysis of all incisional or excisional skin biopsies performed between 2004 and 2008 in a Department of Dermatology. RESULTS: A total of 3075 Non-melanoma skin cancers were identified, representing 88% of all malignant skin neoplasms (n=3493) diagnosed in the same period. Of those, 68,3% were basal cell carcinomas. Most Non-melanoma skin cancer patients were female and over 60 years old. Of all Non-melanoma skin cancer, 81,7% (n=1443) were located in sun-exposed skin, and represented 95,1% of malignant skin neoplasms in sun-exposed skin. Non-melanoma skin cancer was the most frequent malignant skin neoplasm in most topographic locations, except for abdomen and pelvis - over 95% of all malignant skin neoplasms in the face, neck and scalp were Non-melanoma skin cancer. Basal cell carcinomas were clearly predominant in all locations, except in upper and lower limbs, lower lip and genitals...

‣ Human papillomavirus type 16 sequence variants: identification by E6 and L1 lineage-specific hybridization.

Wheeler, C M; Yamada, T; Hildesheim, A; Jenison, S A
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /01/1997 Português
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A catalog of human papillomavirus (HPV) type 16 (HPV-16) E6 and L1 signature nucleotides was used to develop PCR-based oligonucleotide probe systems capable of distinguishing HPV-16 class and subclass variants. Twenty-three E6-specific oligonucleotide probes targeting 13 variant nucleotide positions and 12 L1-specific oligonucleotide probes targeting 6 variant nucleotide positions were used to characterize HPV-16-containing cervicovaginal lavage specimens. Nucleotide positions that could be distinguished included E6 nucleotides 109, 131, 132, 143, 145, 178, 183, 286, 289, 335, 350, 403, and 532 and L1 nucleotides 6695, 6721, 6803, 6854, 6862, and 6994. Combined hybridization patterns were assigned on the basis of the predicted HPV-16 class, subclass, or minor class variants described previously (T. Yamada, C. M. Wheeler, A. L. Halpern, A.-C. M. Stewart, A. Hildesheim, and S.A. Jenison, J. Virol. 69:7743-7753, 1995). The major HPV-16 variant lineages detected included European prototype-like (E-P), Asian (As), Asian-American (AA), and African (Af1 and Af2) lineages. In addition, E-G131, an E-class variant, and AA-G183, an AA-class variant, were also identified. For each clinical specimen, DNA hybridization results were compared to nucleotide sequence determinations. Targeted L1 and E6 marker nucleotides covaried within all HPV-16 variant isolates examined. These hybridization-based methods result in minimal misclassification error...

‣ Methodologic frontiers in environmental epidemiology.

Rothman, K J
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/1993 Português
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Environmental epidemiology comprises the epidemiologic study of those environmental factors that are outside the immediate control of the individual. Exposures of interest to environmental epidemiologists include air pollution, water pollution, occupational exposure to physical and chemical agents, as well as psychosocial elements of environmental concern. The main methodologic problem in environmental epidemiology is exposure assessment, a problem that extends through all of epidemiologic research but looms as a towering obstacle in environmental epidemiology. One of the most promising developments in improving exposure assessment in environmental epidemiology is to find exposure biomarkers, which could serve as built-in dosimeters that reflect the biologic footprint left behind by environmental exposures. Beyond exposure assessment, epidemiologists studying environmental exposures face the difficulty of studying small effects that may be distorted by confounding that eludes easy control. This challenge may prompt reliance on new study designs, such as two-stage designs in which exposure and disease information are collected in the first stage, and covariate information is collected on a subset of subjects in state two. While the analytic methods already available for environmental epidemiology are powerful...

‣ Epidemiology and detection as options for control of viral and parasitic foodborne disease.

Jaykus, L. A.
Fonte: Centers for Disease Control Publicador: Centers for Disease Control
Tipo: Artigo de Revista Científica
Publicado em //1997 Português
Relevância na Pesquisa
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Human enteric viruses and protozoal parasites are important causes of emerging food and waterborne disease. Epidemiologic investigation and detection of the agents in clinical, food, and water specimens, which are traditionally used to establish the cause of disease outbreaks, are either cumbersome, expensive, and frequently unavailable or unattempted for the important food and waterborne enteric viruses and protozoa. However, the recent introduction of regulatory testing mandates, alternative testing strategies, and increased epidemiologic surveillance for food and waterborne disease should significantly improve the ability to detect and control these agents. We discuss new methods of investigating foodborne viral and parasitic disease and the future of these methods in recognizing, identifying, and controlling disease agents.

‣ Invited Commentary: Evaluating Vaccination Programs Using Genetic Sequence Data

Halloran, M. Elizabeth; Holmes, Edward C.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
Português
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Genomic data will become an increasingly important component of epidemiologic studies in coming years. The authors of the accompanying Journal article, van Ballegooijen et al. (Am J Epidemiol. 2009;170(12):1455–1463), are to be commended for attempting to use the coalescent analysis of viral sequence data to evaluate a hepatitis B vaccination program. Coalescent theory attempts to link the phylogenetic history of populations with rates of population growth and decline. In particular, under certain assumptions, a reduction in genetic diversity can be interpreted as a reduction in disease incidence. However, the authors of this commentary contend that van Ballegooijen et al.’s interpretation of changes in viral genetic diversity as a measure of hepatitis B vaccine effectiveness has major limitations. Because of the potential use of these methods in future vaccination studies, the authors discuss the utility of these methods and the data requirements needed for them to be convincing. First, data sets should be large enough to provide sufficient epidemiologic-scale resolution. Second, data need to reflect sufficiently fine-grained temporal sampling. Third, other processes that can potentially influence genetic diversity and confuse demographic inferences should be considered.

‣ Matched-Cohort DNA Microarray Diversity Analysis of Methicillin Sensitive and Methicillin Resistant Staphylococcus aureus Isolates from Hospital Admission Patients

Ruffing, Ulla; Akulenko, Ruslan; Bischoff, Markus; Helms, Volkhard; Herrmann, Mathias; von Müller, Lutz
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 20/12/2012 Português
Relevância na Pesquisa
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As genotyping of S. aureus is important for epidemiologic research and for hygiene management, methods are required for standardized fast and easily applicable evaluation of closely related epidemic strains with high prevalence in hospitals. In this single centre matched control study we compared a new commercially available DNA microarray (IdentiBAC) with standard spa-typing for S. aureus genotyping. Included in the study was a subgroup of 46 MRSA and matched 46 MSSA nasal isolates of the Saarland University Medical Center collected during a state-wide admission prevalence screening. Microarray (MA) and also spa-typing could easily differentiate the genetically diverse MSSA group. However, due to the predominance of CC5/t003 in the MRSA group a sufficient subtyping required analysis of more complex genetic profiles as was shown here by the MA comprising a total number of 334 different hybridization probes. The genetic repertoire of the MRSA group was characterized by more virulence genes as compared to the MSSA group. The standard evaluation of MA results by the original software into CCs, agr-, SCCmec- and capsule-types was substituted in the present study by implementation of multivariate subtyping of closely related CC5 isolates using three different bioinformatic methods (splits graph...

‣ Comparison of Random Forest and Parametric Imputation Models for Imputing Missing Data Using MICE: A CALIBER Study

Shah, Anoop D.; Bartlett, Jonathan W.; Carpenter, James; Nicholas, Owen; Hemingway, Harry
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
Português
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Multivariate imputation by chained equations (MICE) is commonly used for imputing missing data in epidemiologic research. The “true” imputation model may contain nonlinearities which are not included in default imputation models. Random forest imputation is a machine learning technique which can accommodate nonlinearities and interactions and does not require a particular regression model to be specified. We compared parametric MICE with a random forest-based MICE algorithm in 2 simulation studies. The first study used 1,000 random samples of 2,000 persons drawn from the 10,128 stable angina patients in the CALIBER database (Cardiovascular Disease Research using Linked Bespoke Studies and Electronic Records; 2001–2010) with complete data on all covariates. Variables were artificially made “missing at random,” and the bias and efficiency of parameter estimates obtained using different imputation methods were compared. Both MICE methods produced unbiased estimates of (log) hazard ratios, but random forest was more efficient and produced narrower confidence intervals. The second study used simulated data in which the partially observed variable depended on the fully observed variables in a nonlinear way. Parameter estimates were less biased using random forest MICE...

‣ Advancing Research on Racial–Ethnic Health Disparities: Improving Measurement Equivalence in Studies with Diverse Samples

Landrine, Hope; Corral, Irma
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
Publicado em 22/12/2014 Português
Relevância na Pesquisa
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To conduct meaningful, epidemiologic research on racial–ethnic health disparities, racial–ethnic samples must be rendered equivalent on other social status and contextual variables via statistical controls of those extraneous factors. The racial–ethnic groups must also be equally familiar with and have similar responses to the methods and measures used to collect health data, must have equal opportunity to participate in the research, and must be equally representative of their respective populations. In the absence of such measurement equivalence, studies of racial–ethnic health disparities are confounded by a plethora of unmeasured, uncontrolled correlates of race–ethnicity. Those correlates render the samples, methods, and measures incomparable across racial–ethnic groups, and diminish the ability to attribute health differences discovered to race–ethnicity vs. to its correlates. This paper reviews the non-equivalent yet normative samples, methodologies and measures used in epidemiologic studies of racial–ethnic health disparities, and provides concrete suggestions for improving sample, method, and scalar measurement equivalence.

‣ Toward refined estimates of ambient PM2.5 exposure: Evaluation of a physical outdoor-to-indoor transport model

Hodas, Natasha; Meng, Qingyu; Lunden, Melissa M.; Turpin, Barbara J.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/02/2014 Português
Relevância na Pesquisa
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Because people spend the majority of their time indoors, the variable efficiency with which ambient PM2.5 penetrates and persists indoors is a source of error in epidemiologic studies that use PM2.5 concentrations measured at central-site monitors as surrogates for ambient PM2.5 exposure. To reduce this error, practical methods to model indoor concentrations of ambient PM2.5 are needed. Toward this goal, we evaluated and refined an outdoor-to-indoor transport model using measured indoor and outdoor PM2.5 species concentrations and air exchange rates from the Relationships of Indoor, Outdoor, and Personal Air Study. Herein, we present model evaluation results, discuss what data are most critical to prediction of residential exposures at the individual-subject and populations levels, and make recommendations for the application of the model in epidemiologic studies. This paper demonstrates that not accounting for certain human activities (air conditioning and heating use, opening windows) leads to bias in predicted residential PM2.5 exposures at the individual-subject level, but not the population level. The analyses presented also provide quantitative evidence that shifts in the gas-particle partitioning of ambient organics with outdoor-to-indoor transport contribute significantly to variability in indoor ambient organic carbon concentrations and suggest that methods to account for these shifts will further improve the accuracy of outdoor-to-indoor transport models.

‣ Toxicokinetic Modeling of Persistent Organic Pollutant Levels in Blood from Birth to 45 Months of Age in Longitudinal Birth Cohort Studies

Verner, Marc-Andre; Sonneborn, Dean; Lancz, Kinga; Muckle, Gina; Ayotte, Pierre; Dewailly, Éric; Kocan, Anton; Palkovicová, Lubica; Trnovec, Tomas; Haddad, Sami; Hertz-Picciotto, Irva; Eggesbø, Merete
Fonte: National Institute of Environmental Health Sciences Publicador: National Institute of Environmental Health Sciences
Tipo: Artigo de Revista Científica
Português
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Background: Despite experimental evidence that lactational exposure to persistent organic pollutants (POPs) can impact health, results from epidemiologic studies are inconclusive. Inconsistency across studies may reflect the inability of current methods to estimate children’s blood levels during specific periods of susceptibility. Objectives: We developed a toxicokinetic model to simulate blood POP levels in children from two longitudinal birth cohorts and aimed to validate it against blood levels measured at 6, 16, and 45 months of age. Methods: The model consisted of a maternal and a child lipid compartment connected through placental diffusion and breastfeeding. Simulations were carried out based on individual physiologic parameters; duration of breastfeeding; and levels of POPs measured in maternal blood at delivery, cord blood, or breast milk. Model validity was assessed through regression analyses of simulated against measured blood levels. Results: Simulated levels explained between 10% and 83% of measured blood levels depending on the cohort, the compound, the sample used to simulate children’s blood levels, and child’s age when blood levels were measured. Model accuracy was highest for estimated blood POP levels at 6 months based on maternal or cord blood levels. However...

‣ Empirical Likelihood-Based Inference for Multiple Regression and Treatment Comparison

Su, Haiyan ; Liang, Hua
Fonte: Universidade de Rochester Publicador: Universidade de Rochester
Tipo: Tese de Doutorado
Português
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Thesis (Ph.D.)--University of Rochester. School of Medicine and Dentistry. Dept. of Biostatistics and Computational Biology, 2009.; Parameter estimation and statistical inference are generally used in the analysis of epidemiological and biomedical data. Traditional parametric methods often im- pose the assumption of normality on the data. When this assumption is violated, methods based on the normal approximation can give biased results. Furthermore, normal approximation-based inference methods require estimation of the asymp- totic variance, which may be di±cult in semi-parametric or non-linear models. Empirical likelihood is a good alternative to make statistical inference for the parameters when the distribution of the data is unspeci¯ed. To derive statisti- cal inference for the parameter of interest, we develop empirical likelihood-based methods along with the Bartlett correction to improve the coverage probability of the parameter. The contributions we make to the existing literature in this dissertation contain two parts. In the ¯rst part, we develop an empirical likelihood-based inference for multiple regression models and show that the empirical likelihood ratio statistic follows a chi-square limiting distribution for several model settings. For high- dimensional parameter vectors...

‣ Comparison of three inducement techniques to improve compliance in a health survey conducted by telephone.

Hornik, J; Zaig, T; Shadmon, D; Barbash, G I
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em //1990 Português
Relevância na Pesquisa
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The use of telephone interviews for epidemiologic and public health studies has increased in recent years. Since telephone surveys are susceptible to lower response rates than personal interviews, several attempts have been reported to increase respondents' compliance using various precontact procedures. This investigation evaluates the comparative effectiveness of three techniques to enhance compliance with a relatively long telephone interview on epidemiologic topics. The theoretical and practical applications in the domain of telephone surveys of two techniques, the foot-in-the-door and the low ball, commonly considered nonpressure techniques, are discussed. A newly suggested, combined compliance procedure is also introduced and tested. Results show that compliance was greater for the new method when compared with each of the other two methods. Moreover, each of the three methods outperformed a control condition. The theoretical models developed to devise and explain the new techniques received empirical support in a public health survey employing 335 adult residents of Tel Aviv, Israel, in May 1988.