Apesar de existirem evidências suficientes sobre benefícios do aleitamento materno (AM), apenas 35% das crianças são amamentadas exclusivamente até o quarto mês de vida. Visando estender esta prática, OMS/UNICEF lançaram a Iniciativa Hospital Amigo da Criança (IHAC), que estabelece sistema de credenciamento para maternidades de acordo com grau de incentivo ao AM. Esta dissertação pretende investigar a efetividade da IHAC na duração de dois tipos de aleitamento materno: exclusivo (AME) e predominante (AMP) entre crianças usuárias de Unidades Básicas de Saúde (UBS) do Rio de Janeiro. Trata-se de estudo transversal, sendo a população de estudo constituída de 811 mães de crianças menores de 5 meses de idade, selecionadas aleatoriamente em cinco UBS na cidade do Rio de Janeiro. A variável de exposição foi categorizada em local de nascimento ocorridos em HAC, naqueles em vias de receber titulação (EVHAC) e naqueles sem titulação. Os desfechos considerados foram duração do AME e do AMP, que inclui também crianças em AME (AMEP). Na análise dos dados, optou-se pelo modelo log-log complementar, que permitiu recompor experiência longitudinal da coorte através do recordatório alimentar de 7 dias e da informação da idade das mesmas, caracterizando abordagem tipo current status data. Mesmo após controle por variáveis sociodemográficas, relativas ao estilo de vida e aos aspectos psicossociais maternos, à utilização dos serviços de saúde, idade e saúde da criança, houve maior duração do AME e AMEP em crianças nascidas em HAC e EVHAC. As taxas de AME e de AMEP são mais de duas vezes maiores entre recém-nascidos que nasceram em HAC e EVHAC. Tal efeito diminui ao longo da idade da criança, mantendo-se evidente até quatro (EVHAC) e dois (HAC) meses de vida quando se considera AME e até dois (EVHAC) e cinco (HAC) meses quando se considera AMEP. Os resultados confirmam a efetividade da IHAC nesta clientela,especialmente na manutenção de AME e AMEP nos primeiros meses de vida. Estes também sugerem necessidade de fortalecimento da IHAC e maior integração entre maternidades e UBS, visando garantir aleitamento exclusivo até seis meses de vida / Although there are sufficient evidences about breastfeeding (BF) benefits, only 35% of infants worldwide are exclusively breastfed during the first four months of life. As an effort to extend BF duration, WHO/UNICEF launched the Baby-Friendly Hospital Initiative (BFHI), which establishes hospitals accreditation as Baby-Friendly Hospitals (BFH) when it meets the Ten Steps for Successful Breastfeeding. This dissertation aims to investigate the effectiveness of the BFHI on exclusive breastfeeding (EBF) and exclusive plus predominant breastfeeding (EPBF) duration. This is a cross-sectional study with collected information throughout interviews of 811 mothers of children under 5 months old, randomly selected at five health centers in Rio de Janeiro. Exposure variable was classified according to hospitals compliance with the Ten Steps. There were three possible status: accredited hospitals (BFH), working in becoming BFH or certified hospitals (CBFH) and hospitals without BFHI accreditation or certification. Outcomes were EBF and EPBF duration. Data was analyzed by complementary log-log transformation models, which allowed capture cohort longitudinal experience through 7-day feeding recordatory and infants age (current status data). Even after adjusting analysis for sociodemographic, life style and psychological maternal factors, health services use and babies age and state of health, there was longer duration of EBF and EPBF of infants born in BFH and CBFH. EBF and EPBF rates were twice higher in newborns born in BFH and CBFH. This protective effect on EBF and EPBF decreases along childs age and its noticed until four (CBFH) and two (BFH) months of age when EBF is considered and until two (CBFH) and five (EBF) months for EPBF. The finding indicates the effectiveness of BFHI in maintaining EBF and EPBF through the first months of life in this population. In order to extend BF duration until six months of life, as recommended by WHO, it would be necessary not only to strengthen the BFHI but also to develop and encourage more actions in favor of breastfeeding, focusing on primary health care facilities

Apesar de existirem evidências suficientes sobre benefícios do aleitamento materno (AM), apenas 35% das crianças são amamentadas exclusivamente até o quarto mês de vida. Visando estender esta prática, OMS/UNICEF lançaram a Iniciativa Hospital Amigo da Criança (IHAC), que estabelece sistema de credenciamento para maternidades de acordo com grau de incentivo ao AM. Esta dissertação pretende investigar a efetividade da IHAC na duração de dois tipos de aleitamento materno: exclusivo (AME) e predominante (AMP) entre crianças usuárias de Unidades Básicas de Saúde (UBS) do Rio de Janeiro. Trata-se de estudo transversal, sendo a população de estudo constituída de 811 mães de crianças menores de 5 meses de idade, selecionadas aleatoriamente em cinco UBS na cidade do Rio de Janeiro. A variável de exposição foi categorizada em local de nascimento ocorridos em HAC, naqueles em vias de receber titulação (EVHAC) e naqueles sem titulação. Os desfechos considerados foram duração do AME e do AMP, que inclui também crianças em AME (AMEP). Na análise dos dados, optou-se pelo modelo log-log complementar, que permitiu recompor experiência longitudinal da coorte através do recordatório alimentar de 7 dias e da informação da idade das mesmas, caracterizando abordagem tipo current status data. Mesmo após controle por variáveis sociodemográficas, relativas ao estilo de vida e aos aspectos psicossociais maternos, à utilização dos serviços de saúde, idade e saúde da criança, houve maior duração do AME e AMEP em crianças nascidas em HAC e EVHAC. As taxas de AME e de AMEP são mais de duas vezes maiores entre recém-nascidos que nasceram em HAC e EVHAC. Tal efeito diminui ao longo da idade da criança, mantendo-se evidente até quatro (EVHAC) e dois (HAC) meses de vida quando se considera AME e até dois (EVHAC) e cinco (HAC) meses quando se considera AMEP. Os resultados confirmam a efetividade da IHAC nesta clientela,especialmente na manutenção de AME e AMEP nos primeiros meses de vida. Estes também sugerem necessidade de fortalecimento da IHAC e maior integração entre maternidades e UBS, visando garantir aleitamento exclusivo até seis meses de vida / Although there are sufficient evidences about breastfeeding (BF) benefits, only 35% of infants worldwide are exclusively breastfed during the first four months of life. As an effort to extend BF duration, WHO/UNICEF launched the Baby-Friendly Hospital Initiative (BFHI), which establishes hospitals accreditation as Baby-Friendly Hospitals (BFH) when it meets the Ten Steps for Successful Breastfeeding. This dissertation aims to investigate the effectiveness of the BFHI on exclusive breastfeeding (EBF) and exclusive plus predominant breastfeeding (EPBF) duration. This is a cross-sectional study with collected information throughout interviews of 811 mothers of children under 5 months old, randomly selected at five health centers in Rio de Janeiro. Exposure variable was classified according to hospitals compliance with the Ten Steps. There were three possible status: accredited hospitals (BFH), working in becoming BFH or certified hospitals (CBFH) and hospitals without BFHI accreditation or certification. Outcomes were EBF and EPBF duration. Data was analyzed by complementary log-log transformation models, which allowed capture cohort longitudinal experience through 7-day feeding recordatory and infants age (current status data). Even after adjusting analysis for sociodemographic, life style and psychological maternal factors, health services use and babies age and state of health, there was longer duration of EBF and EPBF of infants born in BFH and CBFH. EBF and EPBF rates were twice higher in newborns born in BFH and CBFH. This protective effect on EBF and EPBF decreases along childs age and its noticed until four (CBFH) and two (BFH) months of age when EBF is considered and until two (CBFH) and five (EBF) months for EPBF. The finding indicates the effectiveness of BFHI in maintaining EBF and EPBF through the first months of life in this population. In order to extend BF duration until six months of life, as recommended by WHO, it would be necessary not only to strengthen the BFHI but also to develop and encourage more actions in favor of breastfeeding, focusing on primary health care facilities

Dans le cadre des analyses des données de survie, la comparaison de plusieurs groupes d’individus, où l'événement d'intérêt est censuré par intervalle, représente un défi méthodologique. Lorsque le suivi des patients au cours de l'étude n'est pas continu, l'événement d'intérêt pourra survenir entre deux dates d'observation; il est dit censuré par intervalle. Des tests de comparaisons des distributions des temps de survie pour plusieurs groupes, adaptés à la censure par intervalle, ont été développés (tests du score, tests de pseudo log-rank pondérés, tests des rangs). C’est dans ce contexte que nous avons proposé deux nouveaux tests de comparaisons de groupes adaptés à des situations particulières de censure par intervalle. Le premier test concerne une situation où l’hypothèse alternative considère que les fonctions de risque instantané se croisent. Le second test concerne une situation où la population étudiée comporte une fraction non à risque pour l’événement d’intérêt. Ces deux tests ont fait l'objet d'une application sur des données réelles d'immunologie clinique. / In the context of analysis of survival data, the comparison of several groups of individuals, where the event of interest is interval censored, represents a methodological challenge. When the monitoring of patients during the study is not continuous, the event of interest may occur between two observation dates; it is said "interval censored". Tests of comparisons of survival time distributions for several groups, adapted for interval censoring, have been developed (score tests, weighted pseudo log-rank tests, rank tests). In this context, we have developped two new group comparison tests adapted to the particular situations of interval censoring. The first test apply to a situation where the alternative hypothesis considers that the hazard functions cross. The second test concerns a situation where the study population has a fraction not at risk for the event of interest. Both of these tests have been applied to real clinical immunology dataset.

For current status data, the failure time of interest may not be observed exactly. The type of this data consists only of a monitoring time and knowledge of whether the failure time occurred before or after the monitoring time. In order to be able to obtain more information from this data, so the monitoring time is very important. In this work, the optimal designs for determining the monitoring times such that maximum information may be obtained in bivariate copula model (Clayton) are investigated. Here, the D- optimal criterion is used to decide the best monitoring time Ci (i = 1; ¢ ¢ ¢ ; n), then use these monitoring times Ci to estimate the unknown parameters simultaneously by maximizing the corresponding likelihood function. Ds-optimal designs for estimation of association parameter in the copula model are also discussed. Simulation studies are presented to compare the performance of using monitoring time C¤D and C¤Ds to do the estimation.

Current status data are usually obtained with a failure time variable T which is diffcult observed but can be determined to lie below or above a random monitoring time or inspection time t. In this work we consider bivariate current status data ${t,delta_1,delta_2}$ and assume we have some prior information of the bivariate failure time variables T1 and T2. Our main goal is to find an optimal inspection time for testing the relationship between T1 and T2.

Interval censoring arises frequently in life history data, as individuals are often only observed at a sequence of assessment times. This leads to a situation where we do not know when an event of interest occurs, only that it occurred somewhere between two assessment times. Here, the focus will be on methods of estimation for recurrent event data, current status data, and multistate data, subject to interval censoring. With recurrent event data, the focus is often on estimating the rate and mean functions. Nonparametric estimates are readily available, but are not smooth. Methods based on local likelihood and the assumption of a Poisson process are developed to obtain smooth estimates of the rate and mean functions without specifying a parametric form. Covariates and extra-Poisson variation are accommodated by using a pseudo-profile local likelihood. The methods are assessed by simulations and applied to a number of datasets, including data from a psoriatic arthritis clinic. Current status data is an extreme form of interval censoring that occurs when each individual is observed at only one assessment time. If current status data arise in clusters, this must be taken into account in order to obtain valid conclusions. Copulas offer a convenient framework for modelling the association separately from the margins. Estimating equations are developed for estimating marginal parameters as well as association parameters. Efficiency and robustness to the choice of copula are examined for first and second order estimating equations. The methods are applied to data from an orthopedic surgery study as well as data on joint damage in psoriatic arthritis. Multistate models can be used to characterize the progression of a disease as individuals move through different states. Considerable attention is given to a three-state model to characterize the development of a back condition known as spondylitis in psoriatic arthritis, along with the associated risk of mortality. Robust estimates of the state occupancy probabilities are derived based on a difference in distribution functions of the entry times. A five-state model which differentiates between left-side and right-side spondylitis is also considered, which allows us to characterize what effect spondylitis on one side of the body has on the development of spondylitis on the other side. Covariate effects are considered through multiplicative time homogeneous Markov models. The robust state occupancy probabilities are also applied to data on CMV infection in patients with HIV.

Interval censoring arises frequently in life history data, as individuals are often only observed at a sequence of assessment times. This leads to a situation where we do not know when an event of interest occurs, only that it occurred somewhere between two assessment times. Here, the focus will be on methods of estimation for recurrent event data, current status data, and multistate data, subject to interval censoring. With recurrent event data, the focus is often on estimating the rate and mean functions. Nonparametric estimates are readily available, but are not smooth. Methods based on local likelihood and the assumption of a Poisson process are developed to obtain smooth estimates of the rate and mean functions without specifying a parametric form. Covariates and extra-Poisson variation are accommodated by using a pseudo-profile local likelihood. The methods are assessed by simulations and applied to a number of datasets, including data from a psoriatic arthritis clinic. Current status data is an extreme form of interval censoring that occurs when each individual is observed at only one assessment time. If current status data arise in clusters, this must be taken into account in order to obtain valid conclusions. Copulas offer a convenient framework for modelling the association separately from the margins. Estimating equations are developed for estimating marginal parameters as well as association parameters. Efficiency and robustness to the choice of copula are examined for first and second order estimating equations. The methods are applied to data from an orthopedic surgery study as well as data on joint damage in psoriatic arthritis. Multistate models can be used to characterize the progression of a disease as individuals move through different states. Considerable attention is given to a three-state model to characterize the development of a back condition known as spondylitis in psoriatic arthritis, along with the associated risk of mortality. Robust estimates of the state occupancy probabilities are derived based on a difference in distribution functions of the entry times. A five-state model which differentiates between left-side and right-side spondylitis is also considered, which allows us to characterize what effect spondylitis on one side of the body has on the development of spondylitis on the other side. Covariate effects are considered through multiplicative time homogeneous Markov models. The robust state occupancy probabilities are also applied to data on CMV infection in patients with HIV.

Survival analysis often includes dealing with data that are censored. This thesis focuses on censoring in the form of current status data. We discuss seve- ral methods of regression analysis of current status data and focus mainly on a method that assumes that the time to event follows the additive hazards mo- del. Under the assumption of proportional hazards for the monitoring time, this method does not require knowing the baseline hazard function and allows us to use the theory and software which were developed for Cox model. We also pre- sent a modification of this method, a two-step estimator, and show that it is asymptotically normal and has the advantage of lower asymptotic variance.