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  • 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.
401

A STUDY OF TIES AND TIME-VARYING COVARIATES IN COX PROPORTIONAL HAZARDS MODEL

Xin, Xin 12 September 2011 (has links)
In this thesis, ties and time-varying covariates in survival analysis are investigated. There are two types of ties: ties between event times (Type 1 ties) and ties between event times and the time that discrete time-varying covariates change or "jump"(Type 2 ties). The Cox proportional hazards model is one of the most important regression models for survival analysis. Methods for including Type 1 ties and time-varying covariates in the Cox proportional hazards model are well established in previous studies, but Type 2 ties have been ignored in the literature. This thesis discusses the effect of Type 2 ties on Cox's partial likelihood, the current default method to treat Type 2 ties in statistical packages SAS and R (called Fail before Jump in this thesis), and proposes alternative methods (Random and Equally Weighted) for Type 2 ties. A simulation study as well as an analysis of data sets from real research both suggest that both Random and Equally Weighted methods perform better than the other two methods. Also the effect of the percentages of Type 1 and Type 2 ties on these methods for handling both types of ties is discussed. / NSERC
402

Metabolic factors and risk of prostate, kidney, and bladder cancer

Häggström, Christel January 2013 (has links)
Background: Prostate cancer is the most common cancer in Sweden with around 10,000 new cases every year. Kidney and bladder cancer are less common with 1,000 and 2,000 new cases annually, respectively. The incidence of these cancer sites is higher in developed, than in developing countries, suggesting an association between lifestyle and cancer risk. The aims of this thesis were to investigate body mass index (BMI), blood pressure, and blood levels of glucose, total cholesterol, and triglycerides as risk factors for prostate, kidney, and bladder cancer. Furthermore, we aimed at assess probabilities of prostate cancer and competing events, all-cause death, for men with normal and high levels of metabolic factors. Material and methods: This thesis was conducted within the Metabolic Syndrome and Cancer project (Me-Can), a pooled cohort study with data from 578,700 participants from Norway, Sweden, and Austria. Data from metabolic factors were prospectively collected at health examinations and linked to the Cancer and Cause of Death registers in each country.  Results: High levels of metabolic factors were not associated with increased risk of prostate cancer, but high levels of BMI and blood pressure were associated with risk of prostate cancer death. The probability of prostate cancer was higher for men with normal levels of metabolic factors compared to men with high levels, but the probability of all-cause death, was higher for men with high levels than for those with normal levels. For both men and women, high levels of metabolic factors were associated with increased risk of kidney cancer (renal cell carcinoma). Furthermore, blood pressure for men and BMI for women were found as independent risk factors of kidney cancer. High blood pressure was associated with an increased risk of bladder cancer for men. Conclusions: High levels of metabolic factors were associated to risk of kidney and bladder cancer and to death from kidney, bladder, and prostate cancer. Compared to men with normal levels, men with high levels of metabolic factors had a decreased probability of prostate cancer but an increased probability of all-cause death. / <p>Ytterligare forskningsfinansiärer: World Cancer Research Fund (2007/09) och Wereld Kanker Onderzoek Fonds (R2010/247)</p> / Me-Can
403

Parametric Potential-Outcome Survival Models for Causal Inference

Gong, Zhaojing January 2008 (has links)
Estimating causal effects in clinical trials is often complicated by treatment noncompliance and missing outcomes. In time-to-event studies, estimation is further complicated by censoring. Censoring is a type of missing outcome, the mechanism of which may be non-ignorable. While new estimates have recently been proposed to account for noncompliance and missing outcomes, few studies have specifically considered time-to-event outcomes, where even the intention-to-treat (ITT) estimator is potentially biased for estimating causal effects of assigned treatment. In this thesis, we develop a series of parametric potential-outcome (PPO) survival models, for the analysis of randomised controlled trials (RCT) with time-to-event outcomes and noncompliance. Both ignorable and non-ignorable censoring mechanisms are considered. We approach model-fitting from a likelihood-based perspective, using the EM algorithm to locate maximum likelihood estimators. We are not aware of any previous work that addresses these complications jointly. In addition, we give new formulations for the average causal effect (ACE) and the complier average causal effect (CACE) to suit survival analysis. To illustrate the likelihood-based method proposed in this thesis, the HIP breast cancer trial data \citep{Baker98, Shapiro88} were re-analysed using specific PPO-survival models, the Weibull and log-normal based PPO-survival models, which assume that the failure time and censored time distributions both follow Weibull or log-normal distributions. Furthermore, an extended PPO-survival model is also derived in this thesis, which permits investigation into the impact of causal effect after accommodating certain pre-treatment covariates. This is an important contribution to the potential outcomes, survival and RCT literature. For comparison, the Frangakis-Rubin (F-R) model \citep{Frangakis99} is also applied to the HIP breast cancer trial data. To date, the F-R model has not yet been applied to any time-to-event data in the literature.
404

Empirical Likelihood Method for Ratio Estimation

Dong, Bin 22 February 2011 (has links)
Empirical likelihood, which was pioneered by Thomas and Grunkemeier (1975) and Owen (1988), is a powerful nonparametric method of statistical inference that has been widely used in the statistical literature. In this thesis, we investigate the merits of empirical likelihood for various problems arising in ratio estimation. First, motivated by the smooth empirical likelihood (SEL) approach proposed by Zhou & Jing (2003), we develop empirical likelihood estimators for diagnostic test likelihood ratios (DLRs), and derive the asymptotic distributions for suitable likelihood ratio statistics under certain regularity conditions. To skirt the bandwidth selection problem that arises in smooth estimation, we propose an empirical likelihood estimator for the same DLRs that is based on non-smooth estimating equations (NEL). Via simulation studies, we compare the statistical properties of these empirical likelihood estimators (SEL, NEL) to certain natural competitors, and identify situations in which SEL and NEL provide superior estimation capabilities. Next, we focus on deriving an empirical likelihood estimator of a baseline cumulative hazard ratio with respect to covariate adjustments under two nonproportional hazard model assumptions. Under typical regularity conditions, we show that suitable empirical likelihood ratio statistics each converge in distribution to a 2 random variable. Through simulation studies, we investigate the advantages of this empirical likelihood approach compared to use of the usual normal approximation. Two examples from previously published clinical studies illustrate the use of the empirical likelihood methods we have described. Empirical likelihood has obvious appeal in deriving point and interval estimators for time-to-event data. However, when we use this method and its asymptotic critical value to construct simultaneous confidence bands for survival or cumulative hazard functions, it typically necessitates very large sample sizes to achieve reliable coverage accuracy. We propose using a bootstrap method to recalibrate the critical value of the sampling distribution of the sample log-likelihood ratios. Via simulation studies, we compare our EL-based bootstrap estimator for the survival function with EL-HW and EL-EP bands proposed by Hollander et al. (1997) and apply this method to obtain a simultaneous confidence band for the cumulative hazard ratios in the two clinical studies that we mentioned above. While copulas have been a popular statistical tool for modeling dependent data in recent years, selecting a parametric copula is a nontrivial task that may lead to model misspecification because different copula families involve different correlation structures. This observation motivates us to use empirical likelihood to estimate a copula nonparametrically. With this EL-based estimator of a copula, we derive a goodness-of-fit test for assessing a specific parametric copula model. By means of simulations, we demonstrate the merits of our EL-based testing procedure. We demonstrate this method using the data from Wieand et al. (1989). In the final chapter of the thesis, we provide a brief introduction to several areas for future research involving the empirical likelihood approach.
405

Rating History, Time and The Dynamic Estimation of Rating Migration Hazard

Dang, Huong Dieu January 2010 (has links)
Doctor of Philosophy(PhD) / This thesis employs survival analysis framework (Allison, 1984) and the Cox’s hazard model (Cox, 1972) to estimate the probability that a credit rating survives in its current grade at a certain forecast horizon. The Cox’s hazard model resolves some significant drawbacks of the conventional estimation approaches. It allows a rigorous testing of non-Markovian behaviours and time heterogeneity in rating dynamics. It accounts for the changes in risk factors over time, and features the time structure of probability survival estimates. The thesis estimates three stratified Cox’s hazard models, including a proportional hazard model, and two dynamic hazard models which account for the changes in macro-economic conditions, and the passage of survival time over rating durations. The estimation of these stratified Cox’s hazard models for downgrades and upgrades offers improved understanding of the impact of rating history in a static and a dynamic estimation framework. The thesis overcomes the computational challenges involved in forming dynamic probability estimates when the standard proportionality assumption of Cox’s model does not hold and when the data sample includes multiple strata. It is found that the probability of rating migrations is a function of rating history and that rating history is more important than the current rating in determining the probability of a rating change. Switching from a static estimation framework to a dynamic estimation framework does not alter the effect of rating history on the rating migration hazard. It is also found that rating history and the current rating interact with time. As the rating duration extends, the main effects of rating history and current rating variables decay. Accounting for this decay has a substantial impact on the risk of rating transitions. Downgrades are more affected by rating history and time interactions than upgrades. To evaluate the predictive performance of rating history, the Brier score (Brier, 1950) and its covariance decomposition (Yates, 1982) were employed. Tests of forecast accuracy suggest that rating history has some predictive power for future rating changes. The findings suggest that an accurate forecast framework is more likely to be constructed if non-Markovian behaviours and time heterogeneity are incorporated into credit risk models.
406

Extensões da Distribuição Weibull Aplicadas na Análise de Séries Climatológicas / Weibull Distribution Extensions Applied to Climatological Series Analysis

Reis, Thaís Carolina Santos dos [UNESP] 23 June 2017 (has links)
Submitted by THAIS CAROLINA SANTOS REIS (thais.carolreis@gmail.com) on 2017-12-23T00:12:53Z No. of bitstreams: 1 dissertacao.pdf: 2133624 bytes, checksum: f25eb167a8e2de286e61755cbfe017ff (MD5) / Approved for entry into archive by Claudia Adriana Spindola null (claudia@fct.unesp.br) on 2018-01-03T15:41:54Z (GMT) No. of bitstreams: 1 reis_tcs_me_prud.pdf: 2133624 bytes, checksum: f25eb167a8e2de286e61755cbfe017ff (MD5) / Made available in DSpace on 2018-01-03T15:41:54Z (GMT). No. of bitstreams: 1 reis_tcs_me_prud.pdf: 2133624 bytes, checksum: f25eb167a8e2de286e61755cbfe017ff (MD5) Previous issue date: 2017-06-23 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Na análise de séries climatológicas, a metodologia conhecida como “análise de frequências” inicia-se, após a verificação da validade de algumas suposições, pela escolha e ajuste de uma distribuição de probabilidade. A etapa mais importante desta análise é a escolha ou seleção da distribuição de probabilidade que melhor descreva o verdadeiro comportamento da variável em estudo. Uma vez adotada uma distribuição de probabilidade que esteja bem ajustada, segundo um ou vários critérios, é de interesse, por exemplo, estimar a probabilidade de que eventos de certa magnitude sejam igualados ou excedidos em T anos. O inverso desta probabilidade é chamado de período de retorno, sendo esta uma medida de extrema importância na avaliação de riscos associados a fenômenos climatológicos. Em princípio, qualquer distribuição de probabilidade com suporte nos números reais positivos pode ser utilizada na descrição do comportamento de séries fluviométricas, pluviométricas, eólicas, entre outras. Em se tratando de séries pluviométricas, formadas, por exemplo, pelas pluviosidades diárias, decendiais, mensais, trimestrais e anuais, as distribuições Gama e Weibull são as mais utilizadas. Nos últimos anos, a partir de métodos específicos, uma infinidade de novas distribuições vêm sendo propostas para a análise de observações contínuas e estritamente positivas, cujas aplicações, em sua grande maioria, restringem-se a dados de sobrevivência e confiabilidade. Nesta dissertação de Mestrado, foram avaliadas as performances das distribuições Odd Weibull, Marshall-Olkin Weibull, Weibull exponenciada e Weibull transmutada como alternativas para as distribuições Gama e Weibull na análise de séries pluviométricas históricas, obtidas de 33 estações meteorológicas do Brasil. Concluiu-se que em um contexto geral a distribuição Weibull foi a mais adequada na descrição da variável “precipitação acumulada mensalmente”, contudo, analisando-se pontualmente cada uma das 33 séries, em nove delas uma das extensões foi classificada como a mais adequada na descrição da variável em questão. Diante disso, tal estudo proporcionou a inserção de algumas das recentes extensões da distribuição Weibull na análise de dados climatológicos. / In the climatological series analysis, a methodology known as “frequency analysis” begins, after the validity of some assumptions, by choice and adjustment of a probability distribution. The most important step of this analysis is the choice or selection of probability distribution that best describes the true behavior of the variable under study. Once a probability distribution, that is well adjusted according to one or several criteria, is adopted, it is of interest, for example, to estimate a probability of events of a certain magnitude that are matched or exceeded in T years. The opposite of this probability is called a return period, which is a measure of extreme importance in the evaluation of risks associated with climatological phenomena. In principle, any probability distribution supported by positive real numbers can be used to describe the behavior of fluviometric, pluviometric and wind series, among others. When it comes to the case of rainfall series, formed, for example, by daily, decendial, monthly, quarterly and annual rainfall, the Gamma and Weibull Distributions are more used. In recent years, from specific methods, a plethora of new distributions are being proposed for an analysis of continuous and strictly positive observations, which applications, for the most part, are restricted to survival and reliability data. In this Master’s dissertation, the performances of the Odd Weibull, Marshall-Olkin Weibull, Exponentiated Weibull and Transmutated Weibull Distributions were evaluated as alternatives for the Gamma and Weibull Distributions in the analysis of historical rainfall series, obtained from 33 meteorological stations in Brazil. It was reasoned that in a general context the Weibull Distribution was published in the description of the variable “monthly cumulative precipitation”, however, analyzing each of the 33 series punctually, in nine of them one of the extensions was classified as the most suitable in the description of the variable in question. Thus, such study provided an insight into some of the recent extensions of the Weibull Distribution in the analysis of climatological data.
407

Competing risks methodology in the evaluation of cardiovascular and cancer mortality as a consequence of albuminuria in type 2 diabetes

Feakins, Benjamin January 2016 (has links)
<b>Background:</b> 'Competing risks' are events that either preclude or alter the probability of experiencing the primary study outcome(s). Many standard survival models fail to account for competing risks, introducing an unknown level of bias in their measures of absolute and relative risk. Individuals with type 2 diabetes mellitus (T2DM) and albuminuria are at increased risk of multiple competing causes of mortality, including cardiovascular disease (CVD), cancer and renal disease, yet studies to date have not implemented competing risks methodology. <b>Aim:</b> Using albuminuria in T2DM as a case study, this Thesis set out to quantify differences between standard- and competing-risks-adjusted survival analysis estimates of absolute and relative risk for the outcomes of cardiovascular and cancer mortality. <b>Methods:</b> 86,962 patients aged &ge;35 years with T2DM present on or before 2005 were identified in the Clinical Practice Research Datalink. To quantify differences in measures of absolute risk, cumulative risk estimates for cardiovascular and cancer mortality from standard survival analysis methods (Kaplan-Meier estimator) were compared to those from competing-risks-adjusted methods (cumulative incidence competing risk estimator). Cumulative risk estimates were stratified by patient albuminuria level (normoalbuminuria vs albuminuria). To quantify differences in measures of relative risk, estimates for the effect of albuminuria on the relative hazards of cardiovascular and cancer mortality were compared between standard cause-specific hazard (CSH) models (Cox-proportional-hazards regression), competing risk CSH models (unstratified Lunn-McNeil model), and competing risk subdistribution hazard (SDH) models (Fine-Gray model). <b>Results:</b> Patients with albuminuria, compared to those with normoalbuminuria, were older (p&LT;0.001), had higher systolic blood pressure (p&LT;0.001), had worse glycaemic control (p&LT;0.001), and were more likely to be current or ex-smokers (p&LT;0.001). Over the course of nine years of follow-up 22,512 patients died; 8,800 from CVD, 5,239 from cancer, and 8,473 from other causes. Median follow-up was 7.7 years. In patients with normoalbuminuria, nine-year standard and competing-risks-adjusted cumulative risk estimates for cardiovascular mortality were 11.1% (95% confidence interval (CI): 10.8-11.5%) and 10.2% (95% CI: 9.9-10.5%), respectively. For cancer mortality, these figures were 8.0% (95% CI: 7.7-8.3%) and 7.2% (95% CI: 6.9-7.5%). In patients with albuminuria, standard and competing-risks-adjusted estimates for cardiovascular mortality were 21.8% (95% CI: 20.9-22.7%) and 18.5% (95% CI: 17.8-19.3%), respectively. For cancer mortality, these figures were 10.7% (95% CI: 10.0-11.5%) and 8.6% (8.1-9.2%). For the effect of albuminuria on cardiovascular mortality, hazard ratios from multivariable standard CSH, competing risks CSH, and subdistribution hazard ratios from competing risks SDH models were 1.75 (95% CI: 1.63-1.87), 1.75 (95% CI: 1.64-1.87), and 1.58 (95% CI: 1.48-1.69), respectively. For the effect of albuminuria on cancer mortality, these values were 1.27 (95% CI: 1.16-1.39), 1.28 (95% CI: 1.17-1.40), and 1.11 (95% CI: 1.01-1.21). <b>Conclusions:</b> When evaluating measures of absolute risk, differences between standard and competing-risks-adjusted methods were small in absolute terms, but large in relative terms. For the investigation of epidemiological relationships using relative hazards models, standard survival analysis methods produced near-identical risk estimates to the CSH competing risks methods for the clinical associations evaluated in this Thesis. For the evaluation of risk prediction using relative hazards models, CSH models produced consistently higher risk estimates than SDH models, and their use may lead to over-estimation of the predictive effect of albuminuria on either outcome. Where outcomes are less common (like cancer) CSH models provide poor estimates of risk prediction, and SDH models should be used. This research demonstrates that differences can be present between risk estimates derived using CSH and SDH methods, and that the two are not necessarily interchangeable. Moreover, such differences may be present in other clinical areas.
408

Associação entre complicações perioperatórias e mortalidade, no seguimento de um ano, de pacientes submetidos a cirurgias de fêmur e quadril

Leme, Fabio Caetano Oliveira January 2018 (has links)
Orientador: Lais Helena Navarro e Lima / Resumo: Justificativa e objetivos: a população mundial está vivendo mais, incorrendo em aumento da incidência de doenças musculoesqueléticas com necessidade cirúrgica, sendo que fratura de fêmur (FF) e coxartrose (CXT) são lesões geriátricas típicas. Procedimentos cirúrgicos nessa população são de alto risco de morbimortalidade e há falta de dados nacionais sobre esses desfechos. O objetivo deste estudo foi analisar os eventos adversos intra e pós-operatórios precoces em pacientes submetidos ao tratamento cirúrgico para correção de FF e para CXT e sua associação com a mortalidade em um ano de seguimento pós-operatório. Métodos: foi realizado estudo prospectivo, observacional para avaliar as complicações perioperatórias em pacientes submetidos à cirurgia para correção de FF e tratamento de CXT. Os pacientes foram avaliados em todo o período perioperatório e acompanhados durante um ano. Os testes de t de Student e qui-quadrado foram aplicados para a análise estatística para verificar as relações de dependência. A análise de sobrevivência foi realizada pelo modelo de Kaplan-Meier e pela regressão univariada e multivariada de Cox. Resultados: foram arrolados 235 pacientes candidatos a participar do estudo. Contudo 27 pacientes foram excluídos por diferentes razões. Entre os 208 pacientes inclusos, 42 foram submetidos ao tratamento cirúrgico de CXT; 166, à cirurgia para correção de FF. Houve predomínio de pacientes do sexo feminino no grupo que foi submetido à cirurgia para correção de FF... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Background: The world population is aging, incurring an increase in the incidence of musculoskeletal diseases with surgical necessity. Femur fracture and coxarthrosis are typical geriatric lesions. Surgical procedures in this population are at high risk of morbidity and mortality, and there is a lack of national data on these outcomes. The objective of this study was to describe and analyze early intraoperative and postoperative adverse events in patients undergoing surgical treatment for femoral fracture and for coxarthrosis and its association with mortality in one year of postoperative follow-up. Methods: A prospective, observational study was conducted to evaluate perioperative complications in patients undergoing to surgery for treatment of femur fracture and coxarthrosis. The patients were evaluated throughout the perioperative period and followed up for one year. Student's t-test and chi-square test were applied to the statistical analysis to verify the dependency ratios. Survival analysis was performed using the Kaplan-Meier model and Cox's univariate and multivariate regression. Results: 235 patients were enrolled in the study. However, 27 patients were excluded for different reasons. Among the 208 patients included, 42 underwent surgical treatment of coxarthrosis, 166 to surgery for femoral fracture. There was a predominance of female patients in the group that underwent surgery for femur fracture, while in the group of patients who underwent surgery for correction ... (Complete abstract click electronic access below) / Doutor
409

Associação entre complicações perioperatórias e mortalidade, no seguimento de um ano, de pacientes submetidos a cirurgias de fêmur e quadril / Association between perioperative complications and mortality in the one tear follow-up of patients undergoing femoral and hip surgeries

Leme, Fabio Caetano Oliveira [UNESP] 27 August 2018 (has links)
Submitted by Fabio Caetano Oliveira Leme (fabio.leme@hotmail.com) on 2018-10-10T02:40:34Z No. of bitstreams: 1 TESE ATELIÊ_2out (1).pdf: 1086669 bytes, checksum: a97e594b7be9b6a9762f9990c060effa (MD5) / Approved for entry into archive by ROSANGELA APARECIDA LOBO null (rosangelalobo@btu.unesp.br) on 2018-10-11T13:34:09Z (GMT) No. of bitstreams: 1 leme_fco_me_bot.pdf: 1086669 bytes, checksum: a97e594b7be9b6a9762f9990c060effa (MD5) / Made available in DSpace on 2018-10-11T13:34:09Z (GMT). No. of bitstreams: 1 leme_fco_me_bot.pdf: 1086669 bytes, checksum: a97e594b7be9b6a9762f9990c060effa (MD5) Previous issue date: 2018-08-27 / Justificativa e objetivos: a população mundial está vivendo mais, incorrendo em aumento da incidência de doenças musculoesqueléticas com necessidade cirúrgica, sendo que fratura de fêmur (FF) e coxartrose (CXT) são lesões geriátricas típicas. Procedimentos cirúrgicos nessa população são de alto risco de morbimortalidade e há falta de dados nacionais sobre esses desfechos. O objetivo deste estudo foi analisar os eventos adversos intra e pós-operatórios precoces em pacientes submetidos ao tratamento cirúrgico para correção de FF e para CXT e sua associação com a mortalidade em um ano de seguimento pós-operatório. Métodos: foi realizado estudo prospectivo, observacional para avaliar as complicações perioperatórias em pacientes submetidos à cirurgia para correção de FF e tratamento de CXT. Os pacientes foram avaliados em todo o período perioperatório e acompanhados durante um ano. Os testes de t de Student e qui-quadrado foram aplicados para a análise estatística para verificar as relações de dependência. A análise de sobrevivência foi realizada pelo modelo de Kaplan-Meier e pela regressão univariada e multivariada de Cox. Resultados: foram arrolados 235 pacientes candidatos a participar do estudo. Contudo 27 pacientes foram excluídos por diferentes razões. Entre os 208 pacientes inclusos, 42 foram submetidos ao tratamento cirúrgico de CXT; 166, à cirurgia para correção de FF. Houve predomínio de pacientes do sexo feminino no grupo que foi submetido à cirurgia para correção de FF, enquanto, no grupo de pacientes que foram submetidos à cirurgia para correção de CXT, a predominância foi do sexo masculino. Com relação à classificação do estado físico, a grande maioria dos pacientes submetidos à cirurgia para correção de CXT apresentou-se classificada com ASA I e II, enquanto 53% dos pacientes submetidos à cirurgia para correção de FF apresentaram-se classificados como ASA III e IV. Os pacientes com FF apresentaram idade média de 73,8±12,5 anos, intervalo médio entre a fratura e a cirurgia de 8,1±8,5 dias, e entre a internação e a cirurgia de 4,7±4,8 dias. Os pacientes submetidos ao tratamento para CXT apresentaram idade de 67,2±7,9 anos. Hipotensão destacou-se por ser o evento mais frequente no período intraoperatório. As complicações pós-operatórias mais frequentes foram distúrbio hidroeletrolítico, alteração cognitiva, reinternação, infecção do trato urinário, pneumonia e reabordagem cirúrgica. Nenhum paciente submetido à artroplastia de quadril morreu. Para os pacientes submetidos à correção de FF, a taxa de mortalidade foi de 25,3%. Dentre as causas esclarecidas, a mais comum foi sepse. As complicações pós-operatórias que mostraram relação com aumento da taxa de mortalidade foram idade, intervalo entre internação e cirurgia, distúrbio hidroeletrolítico, insuficiência respiratória, necessidade de intubação orotraqueal, reinternação hospitalar, arritmia e a soma da quantidade de complicações. Na análise multivariada, o modelo estatístico final apresentou as variáveis idade e DHE como as complicações que, conjuntamente, exerceram efeito sobre o aumento da mortalidade no período de 365 dias. Conclusões: as cirurgias para correção de CXT na população estudada relacionou-se com baixa incidência de complicações pós-operatórias e não ocorreram óbitos relacionados a esse procedimento. A taxa de mortalidade encontrada na população de FF, no primeiro ano de seguimento, foi de 25,3%. Idade avançada e distúrbio hidroeletrolítico pós-operatório foram fatores preditores de mortalidade no primeiro ano após cirurgia para pacientes idosos submetidos à correção de FF. / Background: The world population is aging, incurring an increase in the incidence of musculoskeletal diseases with surgical necessity. Femur fracture and coxarthrosis are typical geriatric lesions. Surgical procedures in this population are at high risk of morbidity and mortality, and there is a lack of national data on these outcomes. The objective of this study was to describe and analyze early intraoperative and postoperative adverse events in patients undergoing surgical treatment for femoral fracture and for coxarthrosis and its association with mortality in one year of postoperative follow-up. Methods: A prospective, observational study was conducted to evaluate perioperative complications in patients undergoing to surgery for treatment of femur fracture and coxarthrosis. The patients were evaluated throughout the perioperative period and followed up for one year. Student's t-test and chi-square test were applied to the statistical analysis to verify the dependency ratios. Survival analysis was performed using the Kaplan-Meier model and Cox's univariate and multivariate regression. Results: 235 patients were enrolled in the study. However, 27 patients were excluded for different reasons. Among the 208 patients included, 42 underwent surgical treatment of coxarthrosis, 166 to surgery for femoral fracture. There was a predominance of female patients in the group that underwent surgery for femur fracture, while in the group of patients who underwent surgery for correction of coxarthrosis, the predominance was male. Regarding the classification of the physical condition, the great majority of patients under going surgery for correction of coxarthrosis were classified as ASA I and II, while 53% of patients submitted to surgery for femur fracture were classified as ASA III and IV. Patients with a femoral fracture had a mean age of 73.8 ± 12.5 years, mean interval between fracture and surgery of 8.1 ± 8.5 days, and between hospitalization and surgery of 4.7 ± 4.8 days. Patients submitted to treatment for coxarthrosis presented age of 67.2 ± 7.9 years. Hypotension was noted as the most frequent event in the intraoperative period. The most frequent postoperative complications were hydroeletrolytic disorder, cognitive alteration, rehospitalization, urinary tract infection, pneumonia, need for re- operatorion. No patient undergoing treatment for coxarthrosis died. For patients submitted to femur fracture surgery, the mortality rate was 25.3%. Among the clarified causes of death, the most common was sepsis. The complications that were found to be related to increased mortality were age, interval between hospitalization and surgery, hydroelectrolytic disorder, respiratory failure, need for orotracheal intubation, rehospitalization, arrhythmia, and the sum of the number of complications. After the Multivariate Cox Regression, the final statistical model presented the variables age and hydroelectrolytic diturb as the complications that, all together, had an effect on the increase in mortality in the period of 365 days. Conclusions: surgery to treat coxarthrosis was associated with a low incidence of postoperative complications and there were no deaths related to this procedure. The mortality rate found in the femure fracture population in the first year of follow-up was 25.3%. Advanced age and postoperative hydroelectrolytic disturbance were predictors of mortality in the first year after surgery for elderly patients submitted to femoral fracture correction.
410

Avaliação longitudinal do selamento de dentina cariada em lesões profundas de cárie

Alves, Luana Severo January 2009 (has links)
Este estudo avaliou clínica e radiograficamente dentes com lesões profundas de cárie submetidos ao selamento de dentina cariada por 10 anos. Trinta e dois dentes permanentes foram submetidos à remoção parcial de dentina cariada da parede pulpar da cavidade, remoção completa da dentina cariada das paredes laterais (critério de dureza clínica), forramento com cimento à base de hidróxido de cálcio, selamento provisório por 6-7 meses, reabertura da cavidade (finalidades metodológicas: avaliação clínica da dentina e coleta de uma amostra para análise microbiológica) e restauração. Os pacientes foram avaliados clínica e radiograficamente na consulta inicial, após 6-7 meses, 1 ano e meio, 3, 5 e 10 anos. Análises radiográficas qualitativas (deposição de dentina terciária e profundidade da lesão cariosa) e quantitativas (alterações na densidade radiográfica da zona radiolúcida abaixo da restauração através da subtração radiográfica digital) foram realizadas comparando-se as radiografias bitewings de 6-7 meses, 3 e 10 anos com a radiografia inicial. Dos 32 dentes, um sofreu exposição pulpar durante a remoção do material provisório e foi excluído da amostra. Ao final de 10 anos, um paciente teve sua restauração substituída e quatro desistiram de participar da pesquisa. Dos 26 dentes restantes, 16 apresentaram sucesso da terapia (vitalidade pulpar) e 10 apresentaram insucesso da terapia (5 necroses e 5 fraturas). As taxas de sucesso após 1 ano e meio, 3, 5 e 10 anos foram 97%, 90%, 82% e 63% respectivamente. Dos 16 dentes vitais, 13 foram incluídos nas análises radiográficas. Na maioria dos casos, a profundidade da lesão cariosa reduziu ou permaneceu inalterada (12/13) e foi observada a deposição de dentina terciária (10/13). Não houve alteração na densidade radiográfica da zona radiolúcida nos exames de 6-7 meses e 3 anos, porém observou-se seu aumento significativo na reavaliação de 10 anos. O selamento de dentina cariada mostrou-se uma terapia efetiva para o tratamento de lesões profundas de cárie, sendo capaz de paralisar o processo carioso, promover reações dentino-pulpares e induzir ganho mineral na dentina cariada. / This study assessed clinically and radiographically teeth with deep caries lesions submitted to the sealing of carious dentine over a 10-year period. Thirty-two permanent teeth were submitted to partial caries removal from the pulpal cavity wall, complete removal of carious dentine from the surrounding walls (clinical hardness criteria), capping with a calcium hydroxide cement, temporary sealing for 6-7 months, cavity reopening (methodological purposes: clinical assessment of dentine and collection of a sample for microbiological analysis) and filling. Patients were clinically and radiographically assessed at the initial session and after 1.5; 3; 5 and 10 years. Radiographic assessments were performed comparing bitewing radiographs taken after 6-7 months, 3 and 10 years to the baseline one, both qualitatively (tertiary dentine deposition and lesion depth) and quantitatively (radiographic density changes in the radiolucent zone beneath the restoration using digital subtraction radiography). One tooth had its pulp exposed during temporary sealing removal and was excluded from the sample. Over 10 years, one tooth had its restoration replaced and four quitted the trial. Of the remaining 26 teeth, 16 had therapy success (tooth vitality) and 10 had therapy failure (5 necroses and 5 fractures). Therapy success rates were 97%, 90%, 82% and 63% at 1.5-year, 3-year, 5-year and 10-year follow-ups, respectively. Of the 16 vital teeth, 13 were included in the radiographic analysis. In most cases, lesion depth remained unchanged or decreased (12/13) and tertiary dentine formation was observed (10/13) at the 10-year follow-up. There were no radiographic density changes at 6-7 months and 3-year follow-ups; however, it was observed its increase at the 10-year assessment. Partial carious dentine removal is an effective therapy for deep caries lesions on a long-term basis, being able to arrest carious process, promote pulp-dentin reactions and induce mineral gain in the carious dentine.

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