• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 99
  • 43
  • 9
  • 7
  • 3
  • 3
  • 1
  • 1
  • Tagged with
  • 181
  • 181
  • 91
  • 88
  • 34
  • 33
  • 22
  • 22
  • 20
  • 19
  • 18
  • 17
  • 17
  • 16
  • 15
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Análise de dados categóricos e aplicações /

Netto, Jôira Conceição dos Santos January 2019 (has links)
Orientador: Selene Maria Coelho Loibel / Resumo: Esta dissertação tem como foco a análise de dados categóricos, uma parte integrante da Análise Multivariada que interpreta a informação que está contida em dados discretos provenientes de contagens de eventos, possuindo características de nidas pela combinação das categorias de duas ou mais variáveis. A análise de dados categóricos é de grande importância dentro da Estatística pois tem aplicabilidade em variadas áreas do conhecimento. Os dados utilizados, foram coletados através de um question ário aplicado aos alunos de cinco Escolas Técnicas Estaduais (Etec) que nalizaram os cursos técnicos em 2018 e 2019. A pesquisa teve como objetivo obter dados locais e analisar se os alunos pretendem trabalhar ou continuar estudando na mesma área do curso que estão concluindo, se os alunos estão satisfeitos com os cursos que estão fazendo, se pretendem voltar para Etec e fazer outro curso complementar, entre outros questionamentos. Devido à natureza dos dados obtidos, as técnicas de análise de dados categóricos são adequadas e devem ser aplicadas para modelar e fazer inferências sobre os aspectos de interesse. Esta análise pode levar a resultados que serão de grande utilidade para essas Etecs. / Abstract: This dissertation focuses on the Categorical Data Analysis, an integral part of the Multivariate Analysis, which interprets embedded information in discrete data resulting from event counts, having characteristics de ned by combinations of categories from two or more variables. The categorical data analysis is of considerable importance within Statistics since it has a wide applicability in several areas of knowledge. The data set used was collected through a questionnaire applied to students from ve Public Technical Schools (Etec) that nished the technical courses in 2018 and 2019. The research aims to gather local data and analyze whether students intend to work or continue studying in the same eld of the technical course they are completing, whether students are satis ed with the courses they are attending, whether they want to go back to Etec and take another complementary course, among other questions. Due to the nature of the data obtained, categorized data analysis techniques are adequate and should be applied to model and make inferences about the aspects of interest. This analysis can be leaded to outcomes that will be very useful to these Etecs. / Mestre
72

Bayesian Logistic Regression Model for Siting Biomass-using Facilities

Huang, Xia 01 December 2010 (has links)
Key sources of oil for western markets are located in complex geopolitical environments that increase economic and social risk. The amalgamation of economic, environmental, social and national security concerns for petroleum-based economies have created a renewed emphasis on alternative sources of energy which include biomass. The stability of sustainable biomass markets hinges on improved methods to predict and visualize business risk and cost to the supply chain. This thesis develops Bayesian logistic regression models, with comparisons of classical maximum likelihood models, to quantify significant factors that influence the siting of biomass-using facilities and predict potential locations in the 13-state Southeastern United States for three types of biomass-using facilities. Group I combines all biomass-using mills, biorefineries using agricultural residues and wood-using bioenergy/biofuels plants. Group II included pulp and paper mills, and biorefineries that use agricultural and wood residues. Group III included food processing mills and biorefineries that use agricultural and wood residues. The resolution of this research is the 5-digit ZIP Code Tabulation Area (ZCTA), and there are 9,416 ZCTAs in the 13-state Southeastern study region. For both classical and Bayesian approaches, a training set of data was used plus a separate validation (hold out) set of data using a pseudo-random number-generating function in SAS® Enterprise Miner. Four predefined priors are constructed. Bayesian estimation assuming a Gaussian prior distribution provides the highest correct classification rate of 86.40% for Group I; Bayesian methods assuming the non-informative uniform prior has the highest correct classification rate of 95.97% for Group II; and Bayesian methods assuming a Gaussian prior gives the highest correct classification rate of 92.67% for Group III. Given the comparative low sensitivity for Group II and Group III, a hybrid model that integrates classification trees and local Bayesian logistic regression was developed as part of this research to further improve the predictive power. The hybrid model increases the sensitivity of Group II from 58.54% to 64.40%, and improves both of the specificity and sensitivity significantly for Group III from 98.69% to 99.42% and 39.35% to 46.45%, respectively. Twenty-five optimal locations for the biomass-using facility groupings at the 5-digit ZCTA resolution, based upon the best fitted Bayesian logistic regression model and the hybrid model, are predicted and plotted for the 13-state Southeastern study region.
73

Statistical Modelling Of Financial Statements Of Turkey: A Panel Data Analysis

Akinc, Deniz 01 August 2008 (has links) (PDF)
Financial failure is an important subject for both the economical development of the country and for the self - evaluation of individual companies. Increase in the number of financially failed companies points out the misuse of the country resources. Recently, financial failure threatens both small and large companies in Turkey. It is important to determine factors that affect the financial failure by analyzing models and to use these models for auditing the financial situation. In today&rsquo / s Turkey, the statistical methods that are used for this purpose involve single level models applied to cross-sectional data. However, multilevel models applied to panel data are more preferable as they gather more information, and also, enable the calculated financial success probabilities to be more trustworthy. In this thesis, publicly available panel data that are collected from The Istanbul Stock Exchange are investigated. Mainly, financial success of companies from two sectors, namely industry and services, are investigated. For the analysis of this panel data, data exploration methods, missing data imputation, possible solutions to multicollinearity problem, single level logistic regression models and multilevel models are used. By these models, financial success probabilities for each company are calculated / the factors related to the financial failure are determined, and changes in time are observed. Models and early warning systems resulted in correct classification rates of up to 100%. In the services sector, a small number of companies having publicly available data result in a decline in the success of models. It is concluded that sharing data with more subjects observed in a longer time period collected in the same format with academicians, will result in better justified outputs, which are useful for both academicians and managers.
74

Characterisation of telomere length dynamics in dairy cattle and association with productive lifespan

Seeker, Luise Avelina January 2018 (has links)
Telomeres form protective caps at the ends of linear chromosomes. They consist of repetitive DNA nucleotides and associated proteins of the shelterin complex. In vitro telomeres become shorter during cell division and when a critical shortness is reached they trigger a DNA damage response that leads to replicative senescence or apoptosis. Telomere shortening is a recognised hallmark of cellular ageing and seems to be also associated with organismal ageing. Telomere length (TL) and the rate of shortening vary across individuals and several studies have found that short telomeres and fast telomere depletion are associated with poor survival and early onset of age related diseases. However, longitudinal studies are needed to better understand the relationship of TL and TL dynamics with longevity measures. Relevant studies on livestock species are largely missing from the literature. In the dairy industry, farmers are forced to cull a considerable percentage of their heifers and cows at a young age due to fertility problems or diseases. As a consequence many replacement heifers have to be reared to maintain a specific herd size. This results in increased costs, consumption of resources, and damage to the environment. Breeding for an improved productive lifespan is difficult because longevity measures are recorded at the end of life and are known to have a low heritability. Therefore, the expected genetic improvement is generally slow, but could be considerably accelerated if an early life heritable biomarker was identified that is predictive of productive lifespan and could be used for animal selection. The question is if TL could be used as such a biomarker. The objectives of this thesis were to 1) develop robust methods to measure average relative leukocyte TL (RLTL) in cattle, 2) examine RLTL dynamics with age at a population as well as at an individual level, 3) estimate genetic parameters and 4) assess the association of RLTL and RLTL dynamics with productive lifespan. A quantitative polymerase chain reaction (qPCR) based assay developed for human studies was adapted to cattle and delivered robust results (repeatability > 80%, coefficient of variation=0.05). Different DNA extraction methods were tested for their effect on RLTL measurements and it was demonstrated that fast silica based DNA extraction methods are suitable for telomere projects which can improve the sample throughput and enable large-scale projects. Subsequently, RLTL in 1328 whole blood samples of 308 Holstein Friesian dairy cows and additionally in 284 whole blood samples of 38 female calves was measured. Repeatability and random regression models were used for the statistical analysis of telomere data. RLTL decreased considerably within the first year of life, but remained relatively stable afterwards at population level. Animals varied significantly in their amount and direction of telomere change. The genetic correlation between consecutive measurements in the same individual weakened with increasing sample interval from r=1 to r=0.69 which indicates that TL in the beginning of life might be under a different genetic control than TL later in life. For the first time in a livestock species we calculated heritability estimates for RLTL which were high (0.32-0.38) and remained constant over life. Long telomeres at birth were not predictive of better productive lifespan. However, animals with long RLTL at the ages of one and five years had a survival advantage. Also, animals that showed less average RLTL attrition over their lives remained in production for longer. TL dynamics differed among individuals and a considerable subset of individuals demonstrated telomere lengthening between consecutive measurements. On average, telomeres tend to shorten early in life and then remain relatively constant. While TL is a heritable trait throughout lifetime, telomere change is not heritable. Short TL at specific ages and telomere attrition over life were associated with poorer productive lifespan.
75

Influência local em modelos de regressão. / The local influence in regression models.

LOBATO JÚNIOR, Dorival. 05 July 2018 (has links)
Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-07-05T20:12:22Z No. of bitstreams: 1 DORIVAL LOBATO JÚNIOR - DISSERTAÇÃO PPGMAT 2005..pdf: 658187 bytes, checksum: 934af5bed920aceba4c0f48a5fbca2d6 (MD5) / Made available in DSpace on 2018-07-05T20:12:22Z (GMT). No. of bitstreams: 1 DORIVAL LOBATO JÚNIOR - DISSERTAÇÃO PPGMAT 2005..pdf: 658187 bytes, checksum: 934af5bed920aceba4c0f48a5fbca2d6 (MD5) Previous issue date: 2005-08 / Neste trabalho, estudamos a influência local em modelos de regressão.Este método foi proposto inicialmente por Cook (1986) e tem se mostrado como um poderoso instrumento da análise de diagnóstico. A proposta de Cook consiste em avaliar a curvatura normal de uma superfície, baseada na medida Likelihood Displacement, sob uma pequena peturbação no modelo. Em seguida apresentamos a abordagem de Billor e Loynes (1993), que aplicam uma medida Likelihood Displacement modificada, cuja primeira deriva da não se anula, exceto em casos triviais, com isso a inclinação máxima é usada como medida de influência local. No final, discutimos três aplicações onde utilizamos algumas técnicas gráficas de diagnóstico e as duas propostas de influência local aqui referidas. / In this work, we study the local influence in regression models, this method was offer first of all by Cook(1986) and have show how an important instrument of the diagnostics analysis. The Cook's approach consist in assessing the normal curvature of the geometric surface, using the measure Likelihood Displacement, under an minor perturbations of statistical model. After we present the approach of the Billor and Loynes (1993), that apply an measure Likelihood Displacement changes whose first derivative does not, except in trivial cases, vanish.Thus the maximum slop is using how measure of the local influuence. In finish, we present three apply where use any technic graphics of the diagnostics and the two proposed of the local influence here reported.
76

Índices de capacidade para gráficos de controle baseados em modelos de regressão / Capability indices to control charts based on regression models

Souza, Fernanda Siqueira January 2010 (has links)
Índices de capacidade mal empregados geram conclusões errôneas, comprometendo o estudo e análise do processo, prejudicando o atendimento de exigências gerenciais ou de clientes externos. Assim, o objetivo do presente trabalho é propor índices de capacidade para processos monitorados com gráficos de controle baseado em modelos de regressão conteplando limites simétricos e assimétricos. Realizou-se um mapeamento dos artigos publicados em nove periódicos no período de 2000 a 2009, visando identificar as abordagens pesquisadas sobre capacidade de processos. Um fluxograma orientativo é apresentado, com a finalidade de direcionar a escolha do tipo de gráfico de controle e índices de capacidade para processos com variáveis de resposta: (i) não correlacionadas, (ii) correlacionadas dependentes da variável de controle e (iii) autocorrelacionadas. O uso do fluxograma foi ilustrado através da aplicação do mesmo em um processo de torneamento de uma empresa de máquinas agrícolas. / Capability indices wrongly appointed generate erroneous conclusions, compromising the study and analysis of the process, jeopardizing the fulfillment of the requirements management or external customers. Therefore, the objective of this study is to propose capability indices for processes monitored with control charts based on regression models considering symmetric and asymmetric limits. A mapping of the articles published in nine journals, during the period of 2000 to 2009, was conducted to identify the different approaches surveyed on process capability. A flowchart is presented to direct the choice of control chart and capability indices for processes with response variables: (i) noncorrelated, (ii) correlated dependent control variables and (iii) autocorrelated. The use of the flowchart was illustrated by applying it to the hard turning process of an agricultural machinery company.
77

Proposta de um método para aplicação de gráficos de controle de regressão no monitoramento de processos

Pedrini, Danilo Cuzzuol January 2009 (has links)
O presente trabalho propõe um método para a aplicação do gráfico de controle de regressão para o monitoramento de processos industriais. O método proposto inclui uma modificação do gráfico de controle de regressão múltipla, permitindo o monitoramento direto da característica de qualidade do processo ao invés do monitoramento dos resíduos padronizados do modelo de regressão, facilitando a interpretação dos operadores do processo. O método é dividido em duas fases principais: (i) Fase I - análise retrospectiva e (ii) Fase II - monitoramento do processo. A Fase I é composta pela coleta das amostras iniciais, estimação do modelo de regressão e análise de estabilidade dos dados coletados e, a partir desta fase, define-se alguns parâmetros a serem utilizados na fase seguinte. A Fase II do método consiste na coleta periódica de amostras, verificação da extrapolação dos valores das variáveis de controle e monitoramento do processo propriamente dito. O método proposto foi validado através da aplicação em um processo produtivo e de uma comparação do número médio de amostras (NMA) do gráfico de controle de regressão proposto, gerado através de simulação de Monte Carlo, com outros procedimentos similares encontrados na literatura. Como principais resultados esta dissertação apresenta: (i) proposta de um método sistematizado para nortear a aplicação de gráficos de controle de regressão; (ii) adaptação do gráfico de controle de regressão, de forma a permitir o monitoramento direto da característica de qualidade; (iii) proposta de um procedimento gráfico para a verificação da extrapolação das variáveis de controle e (iv) obtenção do NMA do gráfico de controle de regressão proposto e de outros procedimentos encontrados na literatura. O método proposto foi aplicado em um processo produtivo de uma indústria de borrachas. / This work proposes a method for the application of regression control charts in the monitoring of industrial processes. In order to facilitate the interpretation by the process operators, a modification in the multiple regression control chart is proposed allowing the direct monitoring of the values of quality characteristic of the process, instead of monitoring the regression standardized residuals. The proposed method is divided into two Phases: (i) Phase I, called retrospective analysis, and Phase II, called process monitoring. Phase I is composed by sampling, estimation of linear regression model and verification of stability of these samples. This phase defines some parameters to be used in the following phase. Phase II consists in periodic sampling of the process, altogether with verification of the extrapolation of process control variables and the process monitoring itself. The proposed method was validated through practical application in an industrial process and compared with other procedures found in literature. This work has also achieved the average run length (ARL) of the proposed regression control chart, which was compared with the other procedures consulted. The main contributions of this work may be pointed: (i) the proposal of a method to guide the application of regression control chart; (ii) the adaptation of the multiple regression control chart, allowing the direct monitoring of the quality characteristic; (iii) the proposal of a control chart to monitor the extrapolation of the process control variable and (iv) the obtaining of the ARL of the proposed regression control chart and other similar procedures. The proposed method was applied in a process of a rubber manufactory.
78

Proposta de um método para aplicação de gráficos de controle de regressão no monitoramento de processos

Pedrini, Danilo Cuzzuol January 2009 (has links)
O presente trabalho propõe um método para a aplicação do gráfico de controle de regressão para o monitoramento de processos industriais. O método proposto inclui uma modificação do gráfico de controle de regressão múltipla, permitindo o monitoramento direto da característica de qualidade do processo ao invés do monitoramento dos resíduos padronizados do modelo de regressão, facilitando a interpretação dos operadores do processo. O método é dividido em duas fases principais: (i) Fase I - análise retrospectiva e (ii) Fase II - monitoramento do processo. A Fase I é composta pela coleta das amostras iniciais, estimação do modelo de regressão e análise de estabilidade dos dados coletados e, a partir desta fase, define-se alguns parâmetros a serem utilizados na fase seguinte. A Fase II do método consiste na coleta periódica de amostras, verificação da extrapolação dos valores das variáveis de controle e monitoramento do processo propriamente dito. O método proposto foi validado através da aplicação em um processo produtivo e de uma comparação do número médio de amostras (NMA) do gráfico de controle de regressão proposto, gerado através de simulação de Monte Carlo, com outros procedimentos similares encontrados na literatura. Como principais resultados esta dissertação apresenta: (i) proposta de um método sistematizado para nortear a aplicação de gráficos de controle de regressão; (ii) adaptação do gráfico de controle de regressão, de forma a permitir o monitoramento direto da característica de qualidade; (iii) proposta de um procedimento gráfico para a verificação da extrapolação das variáveis de controle e (iv) obtenção do NMA do gráfico de controle de regressão proposto e de outros procedimentos encontrados na literatura. O método proposto foi aplicado em um processo produtivo de uma indústria de borrachas. / This work proposes a method for the application of regression control charts in the monitoring of industrial processes. In order to facilitate the interpretation by the process operators, a modification in the multiple regression control chart is proposed allowing the direct monitoring of the values of quality characteristic of the process, instead of monitoring the regression standardized residuals. The proposed method is divided into two Phases: (i) Phase I, called retrospective analysis, and Phase II, called process monitoring. Phase I is composed by sampling, estimation of linear regression model and verification of stability of these samples. This phase defines some parameters to be used in the following phase. Phase II consists in periodic sampling of the process, altogether with verification of the extrapolation of process control variables and the process monitoring itself. The proposed method was validated through practical application in an industrial process and compared with other procedures found in literature. This work has also achieved the average run length (ARL) of the proposed regression control chart, which was compared with the other procedures consulted. The main contributions of this work may be pointed: (i) the proposal of a method to guide the application of regression control chart; (ii) the adaptation of the multiple regression control chart, allowing the direct monitoring of the quality characteristic; (iii) the proposal of a control chart to monitor the extrapolation of the process control variable and (iv) the obtaining of the ARL of the proposed regression control chart and other similar procedures. The proposed method was applied in a process of a rubber manufactory.
79

Índices de capacidade para gráficos de controle baseados em modelos de regressão / Capability indices to control charts based on regression models

Souza, Fernanda Siqueira January 2010 (has links)
Índices de capacidade mal empregados geram conclusões errôneas, comprometendo o estudo e análise do processo, prejudicando o atendimento de exigências gerenciais ou de clientes externos. Assim, o objetivo do presente trabalho é propor índices de capacidade para processos monitorados com gráficos de controle baseado em modelos de regressão conteplando limites simétricos e assimétricos. Realizou-se um mapeamento dos artigos publicados em nove periódicos no período de 2000 a 2009, visando identificar as abordagens pesquisadas sobre capacidade de processos. Um fluxograma orientativo é apresentado, com a finalidade de direcionar a escolha do tipo de gráfico de controle e índices de capacidade para processos com variáveis de resposta: (i) não correlacionadas, (ii) correlacionadas dependentes da variável de controle e (iii) autocorrelacionadas. O uso do fluxograma foi ilustrado através da aplicação do mesmo em um processo de torneamento de uma empresa de máquinas agrícolas. / Capability indices wrongly appointed generate erroneous conclusions, compromising the study and analysis of the process, jeopardizing the fulfillment of the requirements management or external customers. Therefore, the objective of this study is to propose capability indices for processes monitored with control charts based on regression models considering symmetric and asymmetric limits. A mapping of the articles published in nine journals, during the period of 2000 to 2009, was conducted to identify the different approaches surveyed on process capability. A flowchart is presented to direct the choice of control chart and capability indices for processes with response variables: (i) noncorrelated, (ii) correlated dependent control variables and (iii) autocorrelated. The use of the flowchart was illustrated by applying it to the hard turning process of an agricultural machinery company.
80

Modelos estatísticos para suporte a avaliação cirúrgica em crianças portadoras de cardiopatias congênitas

Lopes, Marina Travassos 23 February 2017 (has links)
Submitted by Viviane Lima da Cunha (viviane@biblioteca.ufpb.br) on 2017-07-06T13:03:15Z No. of bitstreams: 1 arquivototal.pdf: 2397887 bytes, checksum: 02b09da7c8ccdfb1dbbf31dd43c59ee8 (MD5) / Made available in DSpace on 2017-07-06T13:03:15Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 2397887 bytes, checksum: 02b09da7c8ccdfb1dbbf31dd43c59ee8 (MD5) Previous issue date: 2017-02-23 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Heart diseases are responsible for more deaths in the first year of life than any other congenital problem in Brazil, affecting 8 to 10 children per 1000 live births. There are several types of heart diseases, some heal with time others require surgery. Evaluating the characteristics of the surgeries, it is possible to obtain the probability of the occurrence of postoperative complications and the estimation of the length of stay in the ICU (Intensive Care Unit) that varies according to the typology of this occurrence and the patient health condition. In this sense, the use of statistical models can help to optimize the care of patients in unfavorable clinical conditions. The aim of this study is to develop a tool based on statistical models to assist decision making about the chronological order of the surgeries to be performed. The data from this study came from the charts of the children destined to the execution of the surgery of congenital heart disease in the reference center that composes the Pediatric Cardiology Network PE-PB in the State of Paraíba. A logistic regression model was used to estimate the probability of occurrence of postoperative complications and survival analysis techniques to detect differences between the influence of determining factors on the length of ICU stay after the surgery. All data were analyzed in statistical software R, version 3.2.0. A total of 130 children were included, which 86.15% being below 10 years of age and weighing between 5 and 25 kg. Of the 72 children who presented post-surgical complications, 22.3% presented shunt-type cardiopathy, and 10% had Patent Ductus Arteriosus, followed by 9.2% with Tetralogy of Fallot. The risk factors identified by logistic regression as more associated with the outcome "developing post-surgical complications" were: high risk score (OR = 12.9; p-value = 0.02), presence of acyanotic obstructive heart disease (OR = 12.5, p-value = 0.006), the aortic clamping time during surgery greater than 20 minutes (OR = 3.3; p-value = 0.01), the time of extubation during the surgery (OR = 1.1, p-value = 0.07), presence of pulmonary arterial hypertension (OR = 6.7, p-value = 0.09) and age less than 6 months (OR = 3, 6; p-value = 0.05). In the survival analysis, it was possible to verify that there are statistically significant differences in length of ICU stay between children less than 6 months and older children; Also among children who presented high surgical risk and those who did not present; And among children where there is presence or absence of pulmonary arterial hypertension, in which the presence of some of these characteristics implies a greater probability of permanence for a certain time in the ICU. Also through the survival analysis, it was possible to observe that besides the factors identified through the logistic regression, the occurrence of postoperative infection in children also entails a longer hospitalization time after the surgery. Both techniques analyzed together, were able to build estimates for a certain hospital stay in cases of occurrence or not of postoperative complications, bringing support to hospital planning decisions, resulting in the optimization of the rotation of the available beds, in addition to the suggestion of chronological order of the queue of the next surgeries of congenital cardiopathy to be performed. / As cardiopatias são responsáveis por mais mortes no primeiro ano de vida do que qualquer outro problema congênito no Brasil, acometendo de 8 a 10 crianças a cada 1000 nascidos vivos. Existem diversos tipos de cardiopatia, algumas curam com o tempo, outras requerem intervenções cirúrgicas. Avaliando as características das cirurgias, é possível obter a probabilidade da ocorrência de complicações pós-cirúrgicas, e a estimativa do tempo de internamento em UTI que varia de acordo com a tipologia dessa ocorrência e com o perfil clínico do paciente. Neste sentido, a utilização de modelos estatísticos, pode auxiliar a otimização do cuidado a pacientes em condições clínicas desfavoráveis, sendo a proposta deste estudo, desenvolver uma ferramenta baseada em modelos estatísticos para auxiliar à tomada de decisões acerca da ordem cronológica das cirurgias a serem executadas. Os dados desse estudo provieram dos prontuários das crianças destinadas à execução da cirurgia de cardiopatia congênita no centro de referência que compõe a Rede de Cardiologia Pediátrica PE-PB no Estado da Paraíba. O modelo de regressão logística foi utilizado para estimar a probabilidade de ocorrência de complicações pós-cirúrgicas e as técnicas de análise de sobrevivência, para detectar diferenças entre a influência de fatores determinantes sobre os tempos de internamento em Unidades de Terapia Intensiva após a realização das cirurgias. Todos os dados foram analisados no software estatístico R, versão 3.2.0. Foram incluídas 130 crianças, sendo 86,15% com idade inferior a 10 anos de idade e peso se concentrando entre 5 e 25 quilos. Das 72 crianças que apresentaram complicações pós-cirúrgicas, 22,3% apresentaram a cardiopatia do tipo shunt, e no tocante ao diagnóstico, observou-se que 10% eram portadores de Persistência do Canal Arterial, seguido de 9,2% portadores de Tetralogia de Fallot. Os fatores de risco identificados pela regressão logística como mais associados com o desfecho “desenvolver complicações pós-cirúrgicas” foram: apresentar escore de risco alto (OR=12,9; p-valor=0,02), a presença de cardiopatia acianótica obstrutiva (OR=12,5; p-valor=0,006), o tempo de clampeamento aórtico durante a cirurgia ser superior a 20 minutos (OR=3,3; p-valor=0,01), o tempo de extubação durante a realização da cirurgia (OR=1,1; p-valor=0,07), a presença de hipertensão arterial pulmonar (OR=6,7; p-valor=0,09) e idade inferior a 6 meses (OR=3,6; p-valor=0,05). Na análise de sobrevivência, foi possível constatar que existem diferenças estatisticamente significativas sobre o tempo de internamento em UTI entre as crianças com menos de 6 meses de idade e as crianças com idade superior; também entre as crianças que apresentaram alto risco cirúrgico e as que não apresentaram; e entre as crianças onde há presença ou ausência de hipertensão arterial pulmonar, em que a presença de alguma(s) dessas características implica em maiores probabilidades de permanência por um determinado tempo em UTI. Ainda através da análise de sobrevivência, foi possível observar que além dos fatores identificados através da regressão logística, a ocorrência de infecção pós-operatória nas crianças também acarreta maior tempo de internamento após a cirurgia. Ambas as técnicas analisadas conjuntamente, foram capazes de construir estimativas para um determinado tempo de internamento hospitalar em casos de ocorrência ou não de complicações pós-cirúrgicas, trazendo apoio às decisões do planejamento hospitalar, resultando na otimização da rotatividade dos leitos disponíveis, além da sugestão de ordenação cronológica da fila de espera das próximas cirurgias de cardiopatia congênita a serem executadas.

Page generated in 0.0892 seconds