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Métodos para estimar razão de prevalência em estudos de corte transversal; Methods for estimating prevalence ratios in cross-sectional studies; Métodos para estimar razón de prevalencia en estudios de cohorte transversal

COUTINHO, Leticia M S; SCAZUFCA, Marcia; MENEZES, Paulo R
Fonte: Faculdade de Saúde Pública da Universidade de São Paulo Publicador: Faculdade de Saúde Pública da Universidade de São Paulo
Tipo: Artigo de Revista Científica
POR
Relevância na Pesquisa
65.94%
OBJETIVO: Comparar empiricamente as regressões de Cox, log-binomial, Poisson e logística para estimar razões de prevalência em estudos de corte transversal. MÉTODOS: Foram utilizados dados de um estudo epidemiológico transversal (n=2.072), de base populacional, realizado com idosos na cidade de São Paulo (SP), entre maio de 2003 e abril de 2005. Diagnósticos de demência, possíveis casos de transtorno mental comum e autopercepção de saúde ruim foram escolhidos como desfechos com prevalência baixa, intermediária e alta, respectivamente. Foram utilizadas variáveis de confusão com duas ou mais categorias ou valores contínuos. Valores de referência para estimativas por ponto e por intervalo para as razões de prevalência (RP) foram obtidos pelo método de estratificação de Mantel-Haenszel. Estimativas ajustadas foram calculadas utilizando regressões de Cox e Poisson com variância robusta, e regressão log-binomial. Odds ratios (OR) brutos e ajustados foram obtidos pela regressão logística. RESULTADOS: As estimativas por ponto e por intervalo obtidas pelas regressões de Cox e Poisson foram semelhantes à obtida pela estratificação de Mantel-Haenszel, independentemente da prevalência do desfecho e das covariáveis do modelo. O modelo log-binomial apresentou dificuldade de convergência quando o desfecho tinha prevalência alta e havia covariável contínua no modelo. A regressão logística produziu estimativas por ponto e por intervalo maiores do que as obtidas pelos outros métodos...

Fatores associados à posse de planos privados de saúde médico e odontológico na população infantil: análise transversal da coorte de nascidos vivos de Ribeirão Preto (SP) e São Luís (MA); Factors associated with the possession of private medical and dental health plans in the child population: a cross-sectional analysis of a birth cohort of Ribeirão Preto (SP) and São Luís (MA)

Sena, Marina Fernandes de
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 22/02/2013 PT
Relevância na Pesquisa
65.85%
O mercado de planos privados de saúde apresenta papel de destaque no sistema de saúde no Brasil. Segundo a Pesquisa Nacional por Amostra de Domicílio (PNAD), em 2008, mais de 45,7 milhões de pessoas, cerca de 24% da população brasileira, estava coberta por algum plano de saúde. Melhor facilidade de acesso e utilização dos serviços de saúde por parte dos seus beneficiários pode consistir em um fator que contribua para a expansão do mercado de planos privados de saúde. No Brasil, a abordagem a respeito da posse de planos privados de saúde para crianças é ainda escassa. Neste sentido, o estudo objetiva avaliar os fatores associados à posse de planos privados de saúde médico e odontológico pela população infantil. Estudo transversal foi realizado a partir de dados coletados do seguimento da coorte de nascidos vivos de Ribeirão Preto (SP) (2004/2005) e de São Luís (MA) (2005/2006). A coleta de dados consistiu de um questionário pré-estruturado respondido pelas mães. A população final compreendeu, em Ribeirão Preto/SP, 790 crianças com idade de 10 e 11 anos, tendo um percentual de seguimento de 68,7%, Em São Luís/MA, o total de crianças estudadas foi de 673 com idade de 7 a 9 anos, representando 72,7% das crianças da coorte. Realizou-se análise estatística bivariada seguida de análise multivariável por meio de modelo de equações generalizadas considerando distribuição de Poisson para o cálculo da razão de prevalência...

Facial pain associated with fibromyalgia can be marked by abnormal neuromuscular control: A cross-sectional study

Gui, Maísa Soares; Pedroni, Cristiane Rodrigues; Aquino, Luana M. Martins; Pimentel, Marcele Jardim; Alves, Marcelo Correa; Rossini, Sueli; Reimão, Rubens; Berzin, Fausto; Marques, Amélia Pasqual; Rizzatti-Barbosa, Célia Marisa
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 1092-1101
ENG
Relevância na Pesquisa
65.86%
Background. Temporomandibular disorder (TMD) development in fibromyalgia syndrome (FMS) is not yet fully understood, but altered neuromuscular control in FMS may play a role in triggering TMD. Objective. The purpose of this study was to verify the association between neuromuscular control and chronic facial pain in groups of patients with FMS and TMD. Design. A cross-sectional study was conducted. Methods. This study involved an analysis of facial pain and electromyographic activity of the masticatory muscles in patients with FMS (n=27) and TMD (n=28). All participants were evaluated according to Research Diagnostic Criteria for Temporomandibular Disorders and surface electromyography (SEMG). Myoelectric signal calculations were performed using the root mean square and median frequency of signals. Results. The data revealed premature interruption of masticatory muscle contraction in both patient groups, but a significant correlation also was found between higher median frequency values and increased facial pain. This correlation probably was related to FMS because it was not found in patients with TMD only. Facial pain and increased SEMG activity during mandibular rest also were positively correlated. Limitations. Temporal conclusions cannot be drawn from the study. Also...

Epidemiology of total hip and knee replacement: a cross-sectional study

Lenza,Mario; Ferraz,Silvia de Barros; Viola,Dan Carai Maia; Garcia Filho,Reynaldo Jesus; Cendoroglo Neto,Miguel; Ferretti,Mario
Fonte: Instituto Israelita de Ensino e Pesquisa Albert Einstein Publicador: Instituto Israelita de Ensino e Pesquisa Albert Einstein
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2013 EN
Relevância na Pesquisa
65.85%
OBJECTIVE: To describe the epidemiologic characteristics and adverse events of patients submitted to total hip and total knee replacement. METHODS: A cross-sectional study retrospectively assessing medical chart data of all total hip and total knee replacements performed at a private hospital, between January 2007 and December 2010 Patients submitted to total hip and total knee replacement, with consent of surgeons were included. Incomplete records and/or missing data of the hospital database were excluded. The categorical variables analyzed were age, gender, type of arthroplasty (primary or secondary), type of procedure, duration of surgery, use of drains, risk of infection, compliance to protocol for prevention of deep venous thrombosis and embolism pulmonary, and compliance to the protocol for prevention of infection. The outcomes assessed were adverse events after surgery. RESULTS: A total of 510 patients were included; in that, 166 admissions for knee replacements (92 male) and 344 admissions for hip replacements (176 female). The mean age of patients was 71 years (range 31-99 years). Adverse events were reported in 76 patients (14.9%); there was no correlation between assessed variables and number of complications. CONCLUSION: The results showed no individual factors favoring complications in patients submitted to total hip and total knee replacement; hence...

Prevalence odds ratio or prevalence ratio in the analysis of cross sectional data: what is to be done?

Thompson, M. L.; Myers, J. E.; Kriebel, D.
Fonte: BMJ Group Publicador: BMJ Group
Tipo: Artigo de Revista Científica
Publicado em /04/1998 EN
Relevância na Pesquisa
65.85%
OBJECTIVES: To review the appropriateness of the prevalence odds ratio (POR) and the prevalence ratio (PR) as effect measures in the analysis of cross sectional data and to evaluate different models for the multivariate estimation of the PR. METHODS: A system of linear differential equations corresponding to a dynamic model of a cohort with a chronic disease was developed. At any point in time, a cross sectional analysis of the people then in the cohort provided a prevalence based measure of the effect of exposure on disease. This formed the basis for exploring the relations between the POR, the PR, and the incidence rate ratio (IRR). Examples illustrate relations for various IRRs, prevalences, and differential exodus rates. Multivariate point and interval estimation of the PR by logistic regression is illustrated and compared with the results from proportional hazards regression (PH) and generalised linear modelling (GLM). RESULTS: The POR is difficult to interpret without making restrictive assumptions and the POR and PR may lead to different conclusions with regard to confounding and effect modification. The PR is always conservative relative to the IRR and, if PR > 1, the POR is always > PR. In a fixed cohort and with an adverse exposure...

Obtaining Multistate Life Table Distributions for Highly Refined Subpopulations From Cross-Sectional Data: A Bayesian Extension of Sullivan’s Method

LYNCH, SCOTT M.; BROWN, J. SCOTT
Fonte: Population Association of America Publicador: Population Association of America
Tipo: Artigo de Revista Científica
Publicado em /11/2010 EN
Relevância na Pesquisa
66%
Multistate life table methods are often used to estimate the proportion of remaining life that individuals can expect to spend in various states, such as healthy and unhealthy states. Sullivan’s method is commonly used when panels containing data on transitions are unavailable and true multistate tables cannot be generated. Sullivan’s method requires only cross-sectional mortality data and cross-sectional data indicating prevalence in states of interest. Such data often come from sample surveys, which are widely available. Although the data requirements for Sullivan’s method are minimal, the method is limited in its ability to produce estimates for subpopulations because of limited disaggregation of data in cross-sectional mortality files and small cell sizes in aggregated survey data. In this article, we develop, test, and demonstrate a method that adapts Sullivan’s approach to allow the inclusion of covariates in producing interval estimates of state expectancies for any desired subpopulation that can be specified in the cross-sectional prevalence data. The method involves a three-step process: (1) using Gibbs sampling to sample parameters from a bivariate regression model; (2) using ecological inference for producing transition probability matrices from the Gibbs samples; (3) using standard multistate calculations to convert the transition probability matrices into multistate life tables.

A cross-sectional survey of supports for evidence-informed decision-making in healthcare organisations: a research protocol

Ouimet, Mathieu; Lavis, John N; Léon, Grégory; Ellen, Moriah E; Bédard, Pierre-Olivier; Grimshaw, Jeremy M; Gagnon, Marie-Pierre
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
75.99%
Background: This protocol builds on the development of a) a framework that identified the various supports (i.e. positions, activities, interventions) that a healthcare organisation or health system can implement for evidence-informed decision-making (EIDM) and b) a qualitative study that showed the current mix of supports that some Canadian healthcare organisations have in place and the ones that are perceived to facilitate the use of research evidence in decision-making. Based on these findings, we developed a web survey to collect cross-sectional data about the specific supports that regional health authorities and hospitals in two Canadian provinces (Ontario and Quebec) have in place to facilitate EIDM. Methods/design This paper describes the methods for a cross-sectional web survey among 32 regional health authorities and 253 hospitals in the provinces of Quebec and Ontario (Canada) to collect data on the current mix of organisational supports that these organisations have in place to facilitate evidence-informed decision-making. The data will be obtained through a two-step survey design: a 10-min survey among CEOs to identify key units and individuals in regard to our objectives (step 1) and a 20-min survey among managers of the key units identified in step 1 to collect information about the activities performed by their unit regarding the acquisition...

Cross-Sectional Analyses of Climate Change Impacts

Mendelsohn, Robert; Dinar, Ariel; Basist, Alan; Kurukulasuriya, Pradeep; Ihsan Ajwad, Mohamed; Kogan, Felix; Williams, Claude
Fonte: World Bank, Washington, D.C. Publicador: World Bank, Washington, D.C.
EN_US
Relevância na Pesquisa
66.05%
The authors explore the use of cross-sectional analysis to measure the impacts of climate change on agriculture. The impact literature, using experiments on crops in laboratory settings combined with simulation models, suggests that agriculture will be strongly affected by climate change. The extent of these effects varies by country and region. Therefore, local experiments are needed for policy purposes, which becomes expensive and difficult to implement for most developing countries. The cross-sectional technique, as an alternative approach, examines farm performance across a broad range of climates. By seeing how farm performance changes with climate, one can estimate long-run impacts. The advantage of this approach is that it fully captures adaptation as each farmer adapts to the climate they have lived in. The technique measures the full net cost of climate change, including the costs as well as the benefits of adaptation. However, the technique is not concern-free. The four chapters in this paper examine important potential concerns of the cross-sectional method and how they could be addressed...

Welfare Dynamics Measurement : Two Definitions of a Vulnerability Line and Their Empirical Application

Dang, Hai-Anh H.; Lanjouw, Peter F.
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
EN_US
Relevância na Pesquisa
65.93%
Little research currently exists on a vulnerability line that distinguishes the poor population from the population that is not poor but that still faces significant risk of falling back into poverty. This paper attempts to fill this gap by proposing vulnerability lines that can be straightforwardly estimated with panel or cross-sectional household survey data, in rich- and poor-country settings. These vulnerability lines offer a means to broaden traditional poverty analysis and can also assist with the identification of the middle class or resilient population groups. Empirical illustrations are provided using panel data from the United States (Panel Study of Income Dynamics) and Vietnam (Vietnam Household Living Standards Survey) for the period 2004-2008 and cross-sectional data from India (National Sample Survey) for the period 2004-2009. The estimation results indicate that in Vietnam and India during this time period, the population living in poverty and the middle class have been falling and expanding...

Cross-sectional anthropometry: what can it tell us about the health of young children

McMurray, Christine
Fonte: Health Transition Centre, National Centre for Epidemiology and Population Health, The Australian National University Publicador: Health Transition Centre, National Centre for Epidemiology and Population Health, The Australian National University
Tipo: Artigo de Revista Científica Formato: 72402 bytes; application/pdf
EN_AU
Relevância na Pesquisa
75.89%
It has become common practice in health surveys to collect anthropometric measurements from young children. These datasets comprise one-point-in-time measurements for a number of children, and are very different in character from longitudinal data such as those collected during growth monitoring. This paper explores the nature of cross-sectional data, their applications and their limitations, using sample data from Burundi, Uganda and Zimbabwe. Methods of analysis which treat the data as continuous or dichotomous are compared. The conclusion is that crosssectional data can make a valuable contribution to health research provided their application and interpretation are properly understood.; no

Moving beyond essential interventions for reduction of maternal mortality (the WHO Multicountry Survey on Maternal and Newborn Health): a cross-sectional study

Souza, J.; Crowther, C.
Fonte: Lancet Ltd Publicador: Lancet Ltd
Tipo: Artigo de Revista Científica
Publicado em //2013 EN
Relevância na Pesquisa
65.85%
BACKGROUND We report the main findings of the WHO Multicountry Survey on Maternal and Newborn Health (WHOMCS), which aimed to assess the burden of complications related to pregnancy, the coverage of key maternal health interventions, and use of the maternal severity index (MSI) in a global network of health facilities. METHODS In our cross-sectional study, we included women attending health facilities in Africa, Asia, Latin America, and the Middle East that dealt with at least 1000 childbirths per year and had the capacity to provide caesarean section. We obtained data from analysis of hospital records for all women giving birth and all women who had a severe maternal outcome (SMO; ie, maternal death or maternal near miss). We regarded coverage of key maternal health interventions as the proportion of the target population who received an indicated intervention (eg, the proportion of women with eclampsia who received magnesium sulphate). We used areas under the receiver operator characteristic curves (AUROC) with 95% CI to externally validate a previously reported MSI as an indicator of severity. We assessed the overall performance of care (ie, the ability to produce a positive effect on health outcomes) through standardised mortality ratios. RESULTS From May 1...

Estimating cohort health expectancies from cross-sectional surveys of disability

Davis, B. A; Heathcote, Christopher; O'Neill, Terry
Fonte: Universidade Nacional da Austrália Publicador: Universidade Nacional da Austrália
Tipo: Working/Technical Paper Formato: 115964 bytes; application/pdf
EN_AU
Relevância na Pesquisa
75.87%
A life history can be regarded as a random process that evolves with age through various states of health before terminating with absorption into the state of death. Health expectancies are the occupation times of the non-absorbing states and their estimation is of interest. A continuing major problem has been the lack of satisfactory longitudinal data on which to base estimates and as a result standard inferential techniques may not be relevant. Supposing only cross-sectional data available, we propose a method that is generally applicable and first estimates a logistic parametrization of the probabilities of the various states. A large sample approximation is obtained for the distribution of age specific log (odds). Parameters are estimated by weighted least squares, and this in turn leads to estimates of cohort health expectancies. A result of Liang and Zeger is used to find standard errors. The method is illustrated by application to Australian data from the health surveys of 1981, 1988 and 1993.; no

Medidas de associação em estudo transversal com delineamento complexo: razão de chances e razão de prevalência; Association measures in cross-sectional studies with complex sampling: odds ratio and prevalence ratio

FRANCISCO, Priscila Maria S. Bergamo; DONALISIO, Maria Rita; BARROS, Marilisa Berti de Azevedo; CESAR, Chester Luis Galvão; CARANDINA, Luana; GOLDBAUM, Moisés
Fonte: Associação Brasileira de Pós -Graduação em Saúde Coletiva Publicador: Associação Brasileira de Pós -Graduação em Saúde Coletiva
Tipo: Artigo de Revista Científica
POR
Relevância na Pesquisa
65.92%
O objetivo deste estudo foi apresentar e discutir a utilização das medidas de associação: razão de chances e razão de prevalências, em dados obtidos de estudo transversal realizado em 2001-2002, utilizando-se amostra estratificada por conglomerados em dois estágios (n=1.958). As razões de chances e razões de prevalências foram estimadas por meio de regressão logística não condicional e regressão de Poisson, respectivamente, utilizando-se o pacote estatístico Stata 7.0. Intervalos de confiança e efeitos do desenho foram considerados na avaliação da precisão das estimativas. Dois desfechos do estudo transversal com diferentes níveis de prevalência foram avaliados: vacinação contra influenza (66,1%) e doença pulmonar referida (6,9%). Na situação em que a prevalência foi alta, as estimativas das razões de prevalência foram mais conservadoras com intervalos de confiança menores. Na avaliação do desfecho de baixa prevalência, não se observaram grandes diferenças numéricas entre as estimações das razões de chances e razões de prevalência e erros-padrão obtidos por uma ou outra técnica. O efeito do desenho maior que a unidade indicou que a amostragem complexa, em ambos os casos, aumentou da variância das estimativas. Cabe ao pesquisador a escolha da técnica e do estimador mais adequado ao seu objeto de estudo...

Contraceptive utilization and associated factors among HIV positive women on chronic follow up care in tigray region, northern ethiopia: a cross sectional study

Melaku, Y.A.; Zeleke, E.G.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em //2014 EN
Relevância na Pesquisa
65.85%
BACKGROUND: In sub-Sahara Africa, more than 60% of all new HIV infections are occurring in women, infants and young children. Maternal to child transmission is responsible for 90% of childhood HIV infection. Preventing unwanted pregnancy among HIV positive women is imperative to reduce maternal and infant morbidity and mortality. METHODS: A cross-sectional survey was conducted among 964 HIV positive women in selected 12 health centers of Tigray region. In this paper, analysis was restricted only for 847 women who were sexually active and non-pregnant. In each health center the number of study participants was allocated proportionally to the load of HIV positive women in chronic care clinics. The data were entered into EpiData version 3.1, and cleaned and analyzed using Stata version 11.1. Descriptive summary of data and logistic regression were used to identify possible predictors using odds ratio with 95% confidence interval and P-value of 0.05. FINDINGS: Three hundred ninety four (46.5%) of all HIV positive women had intension to have more children. Three hundred seventy five (44.3%) were using contraceptive methods at time of survey. Injectable (70.7%) and male condom (47.6%) were most commonly used type of contraceptives. In the multivariable analysis...

Cross-sectional dependence in idiosyncratic volatility

Kalnina, Ilze; Tewou, Kokouvi
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
65.94%
This paper introduces a framework for analysis of cross-sectional dependence in the idiosyncratic volatilities of assets using high frequency data. We first consider the estimation of standard measures of dependence in the idiosyncratic volatilities such as covariances and correlations. Next, we study an idiosyncratic volatility factor model, in which we decompose the co-movements in idiosyncratic volatilities into two parts: those related to factors such as the market volatility, and the residual co-movements. When using high frequency data, naive estimators of all of the above measures are biased due to the estimation errors in idiosyncratic volatility. We provide bias-corrected estimators and establish their asymptotic properties. We apply our estimators to high-frequency data on 27 individual stocks from nine different sectors, and document strong cross-sectional dependence in their idiosyncratic volatilities. We also find that on average 74% of this dependence can be explained by the market volatility.

Testing Weak Cross-Sectional Dependence in Large Panels

Pesaran, M. Hashem
Fonte: Faculty of Economics, University of Cambridge, UK Publicador: Faculty of Economics, University of Cambridge, UK
Tipo: Trabalho em Andamento
Relevância na Pesquisa
65.87%
(DISCLAIMER: Not all mathematical symbols in the abstract will display properly - please see the abstract in the pdf). This paper considers testing the hypothesis that errors in a panel data model are weakly cross sectionally dependent, using the exponent of cross-sectional dependence, introduced recently in Bailey, Kapetanios and Pesaran (2012). It is shown that the implicit null of the CD test depends on the relative expansion rates of N and T. When T = O (Nsuperscript6), for some 0 < ? ? 1, then the implicit null of the CD test is given by 0 ? ? < (2 ? ?) / 4, which gives 0 ? ? < ?, when N and T tend to infinity at the same rate such that T/N 0 ? ? < ?, with ? being a finite positive constant. It is argued that in the case of large N panels, the null of weak dependence is more appropriate than the null of independence which could be quite restrictive for large panels. Using Monte Carlo experiments, it is shown that the CD test has the correct size for values of ? in the range [0, 1/4], for all combinations of N and T, and irrespective of whether the panel contains lagged values of the dependent variables, so long as there are no major asymmetries in the error distribution.

Unintended pregnancy among female sex workers in Mekelle city, northern Ethiopia: a cross-sectional study

Weldegebreal, R.; Melaku, Y.A.; Alemayehu, M.; Gebrehiwot, T.G.
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
Publicado em //2015 EN
Relevância na Pesquisa
65.85%
BACKGROUND: Unintended pregnancy is a significant public health concern in the world. Particularly, female sex workers are exposed to the risk of unintended pregnancy, abortion and their consequences. The aim of this study was, therefore, to assess unintended pregnancy and associated factors among female sex workers in Mekelle city, northern Ethiopia. METHODS: A community based cross-sectional study was conducted among 346 female sex workers from five Kebelles (smallest administrative units in Ethiopia) of Mekelle city from March-April, 2014. Sex workers were selected with simple random sampling technique using sampling frame obtained from urban health extension program. Epi-data version 3.1 was used to enter data and analysis was done using SPSS version 20. Bivariate and multivariate logistic regressions were performed to identify factors associated with unintended pregnancy using odds ratio and 95% confidence interval with P-value of 0.05. RESULTS: The magnitude of unintended pregnancy among female sex workers in the past two years was 28.6%. During this period, 59 women had abortion which represents three-fifths, (59.6%), of those who had unintended pregnancies, and 17.1% of all female sex workers. Female sex workers who gave birth and had history of abortion formerly had 3.1 (AOR = 3.07...

Sexual and reproductive health communication and awareness of contraceptive methods among secondary school female students, northern Ethiopia: a cross-sectional study

Melaku, Y.A.; Berhane, Y.; Kinsman, J.; Reda, H.L.
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
Publicado em //2014 EN
Relevância na Pesquisa
65.87%
BACKGROUND: Adolescent girls continue to fall victim to unintended pregnancy and its consequences, with particular problems arising in low income countries. Awareness about methods of contraception is an important step towards gaining access and using suitable contraceptive methods. However, studies assessing the relationship between sexual and reproductive health communication and awareness of contraceptive methods among secondary school female students are lacking. METHODS: A cross sectional study was conducted among 807 female students in six secondary schools in Mekelle town, Ethiopia. Study participants were selected with a stratified cluster sampling technique. Data collection was carried out using a structured, self-administered questionnaire, and data entry was done using EPI Info Version 3.3.2 software. The data were then cleaned and analyzed using SPSS version 20. Bivariate and multivariate logistic regressions were used to determine factors associated with awareness of female students on methods of contraception. RESULT: Of all the students, 127(15.8%) reported ever having had sex, of whom 109(85.8%) had ever used contraceptives. Twenty (16%) of the sexually active students reported having been pregnant, of whom 18(90%) terminated their pregnancies with induced abortion. Discussion on sexual and reproductive health matters with their parent/s and peer/s in the six months prior to the study was reported by 351(43.5%) and 493(61.1%) of the students respectively. 716(88%) students were aware of different methods of contraception. Discussing sexual and reproductive health issues with parents (AOR=2.56(95% CI: 1.45...

Cross-Sectional and Longitudinal Patterns of Dedifferentiation in Late-Life Cognitive and Sensory Function: The Effects of Age, Ability, Attrition, and Occasion of Measurement

Anstey, Kaarin; Hofer, Scott; Luszcz, Mary A
Fonte: American Psychological Association Publicador: American Psychological Association
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
65.86%
The dedifferentiation hypothesis is examined with respect to age-group differences, ability-group differences, attrition-group differences, and time. Cognitive and sensory data were analyzed from individuals (n = 1,823) who completed a clinical assessment on at least 1 of 3 occasions of measurement in the Australian Longitudinal Study of Ageing. Inconsistent dedifferentiation effects were associated with low ability and early attrition from the study, but age-related dedifferentiation was not found. Longitudinal analyses confirmed the cross-sectional analyses. Even though instances of dedifferentiation were identified between pairs of sensory and cognitive variables, consistent patterns of dedifferentiation were not found. These results do not support the view that shared biological factors become increasingly important for explaining within-individual change in cognitive and sensory function in later life.

Métodos para estimar razão de prevalência em estudos de corte transversal; Métodos para estimar razón de prevalencia en estudios de cohorte transversal; Methods for estimating prevalence ratios in cross-sectional studies

Coutinho, Leticia M S; Scazufca, Marcia; Menezes, Paulo R
Fonte: Universidade de São Paulo. Faculdade de Saúde Pública Publicador: Universidade de São Paulo. Faculdade de Saúde Pública
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; ; Formato: application/pdf; application/pdf
Publicado em 01/12/2008 POR; ENG
Relevância na Pesquisa
65.94%
OBJECTIVE: To empirically compare the Cox, log-binomial, Poisson and logistic regressions to obtain estimates of prevalence ratios (PR) in cross-sectional studies. METHODS: Data from a population-based cross-sectional epidemiological study (n = 2072) on elderly people in Sao Paulo (Southeastern Brazil), conducted between May 2003 and April 2005, were used. Diagnoses of dementia, possible cases of common mental disorders and self-rated poor health were chosen as outcomes with low, intermediate and high prevalence, respectively. Confounding variables with two or more categories or continuous values were used. Reference values for point and interval estimates of prevalence ratio (PR) were obtained by means of the Mantel-Haenszel stratification method. Adjusted PR estimates were calculated using Cox and Poisson regressions with robust variance, and using log-binomial regression. Crude and adjusted odds ratios (ORs) were obtained using logistic regression. RESULTS: The point and interval estimates obtained using Cox and Poisson regressions were very similar to those obtained using Mantel-Haenszel stratification, independent of the outcome prevalence and the covariates in the model. The log-binomial model presented convergence difficulties when the outcome had high prevalence and there was a continuous covariate in the model. Logistic regression produced point and interval estimates that were higher than those obtained using the other methods...