Academic literature on the topic 'Kaplan-Meier Estimate'
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Journal articles on the topic "Kaplan-Meier Estimate"
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Kishore, Jugal, ManishKumar Goel, and Pardeep Khanna. "Understanding survival analysis: Kaplan-Meier estimate." International Journal of Ayurveda Research 1, no. 4 (2010): 274. http://dx.doi.org/10.4103/0974-7788.76794.
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Kalra, Aakshi. "The basics of Kaplan–Meier estimate." Journal of the Practice of Cardiovascular Sciences 2, no. 3 (2016): 187. http://dx.doi.org/10.4103/2395-5414.201381.
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Dabrowska, Dorota M. "Kaplan-Meier Estimate on the Plane." Annals of Statistics 16, no. 4 (1988): 1475–89. http://dx.doi.org/10.1214/aos/1176351049.
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Plante, Jean-François. "About an adaptively weighted Kaplan-Meier estimate." Lifetime Data Analysis 15, no. 3 (2009): 295–315. http://dx.doi.org/10.1007/s10985-009-9120-x.
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Stute, Winfried, and Jane-Ling Wang. "The Jackknife Estimate of a Kaplan-Meier Integral." Biometrika 81, no. 3 (1994): 602. http://dx.doi.org/10.2307/2337132.
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STUTE, WINFRIED, and JANE-LING WANG. "The jackknife estimate of a Kaplan—Meier integral." Biometrika 81, no. 3 (1994): 602–6. http://dx.doi.org/10.1093/biomet/81.3.602.
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Hwang, Changha, and Jooyong Shim. "Smoothing Kaplan-Meier estimate using monotone support vector regression." Journal of the Korean Data and Information Science Society 23, no. 6 (2012): 1045–54. http://dx.doi.org/10.7465/jkdi.2012.23.6.1045.
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MICHALAK, MICHAŁ, MAREK POWIDZKI, and JERZY A. MOCZKO. "APPLICATION BOOTSTRAPPING KAPLAN-MEIER ESTIMATE FOR SURVIVAL CURVE SMOOTHING." Computational Methods in Science and Technology 8, no. 2 (2002): 58–64. http://dx.doi.org/10.12921/cmst.2002.08.02.58-64.
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Dabrowska, Dorota M. "Uniform Consistency of the Kernel Conditional Kaplan-Meier Estimate." Annals of Statistics 17, no. 3 (1989): 1157–67. http://dx.doi.org/10.1214/aos/1176347261.
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Ying, Z., and L. J. Wei. "The Kaplan-Meier Estimate for Dependent Failure Time Observations." Journal of Multivariate Analysis 50, no. 1 (1994): 17–29. http://dx.doi.org/10.1006/jmva.1994.1031.
Full textDissertations / Theses on the topic "Kaplan-Meier Estimate"
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Menezes, Rosilene de Melo. "Estudo clínico, patológico e detecção do papillomavírus humano no carcinoma de células escamosas de orofaringe tratados por cirurgia." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/5/5155/tde-16022017-144922/.
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Introdução: O câncer de orofaringe representa 10 a 12 % entre todos os tumores malignos do trato aero digestivo superior com incidência crescente nos Estados Unidos e Europa. O Papillomavírus humano (HPV) está associado aos tumores de orofaringe em até 63%, promovendo uma evolução e prognóstico melhor. Objetivo: Descrever a prevalência do HPV em carcinomas de células escamosas de orofaringe tratados por cirurgia. Analisar a associação entre a presença do HPV e as características demográficas, clínicas, patológicas e terapêuticas. Avaliar a importância da presença do HPV na sobrevida livre de doença e sobrevida global. Método: Pesquisamos a presença do Papillomavirus humano, por PCR, no anátomo patológico. A descrição da amostra foi realizada através de média, frequência absoluta e relativa. Foi estimada a prevalência do HPV e seu respectivo intervalo de 95% de confiança. A análise da associação entre a presença de HPV e as características demográficas, clínicas e patológicas, foi feita pelo teste de associação pelo quiquadrado. A análise da sobrevida livre de doença e sobrevida global foi feita pelo estimador produto limite de Kaplan-Meier e modelos de risco proporcionais de Cox. Resultados: Os pacientes apresentavam idade variando de 34 a 78 anos, com uma média de 56,9 anos. Apenas 10 mulheres no estudo, totalizando com 76 homens. A maioria dos pacientes eram brancos (83,7%). Até 6 meses foi o tempo que a maioria dos pacientes apresentaram como início dos sintomas (69,0%). O sintoma mais comum foi a odinofagia (38,4%). A amígadala foi a localização mais frequente (69,8%). Quanto ao estádio clínico, o III e o IV apresentavam a maior frequência (71,4%). Forma realizadas cirurgias amplas como as bucofaringectomias em 76 pacientes (88,4%). O esvaziamento cervical ipsilateral foi realizado em 81 pacientes (94,2%) e no contralateral em apenas 21 (24,4%). A prevalência do HPV foi de 57%, e o tipo mais comum foi o 16, em 83,6%. A única associação estatisticamente significativa entre as variáveis do estudo com o HPV, foi o tabagismo, onde todos os não fumantes apresentavam HPV. As taxas de sobrevida livre de doença foram 73,9%, 65,9 e 57,9% respectivamente para 12, 24 e 60 meses. Houve diferença estatisticamente significativa com piores taxas, para idade menor que 55 anos e margens comprometidas. A presença do HPV não influenciou a sobrevida livre de doença, nem a sobrevida global. As taxas de sobrevida global foram 75,6%, 54,7% e 43,0%, respectivamente aos 12, 24 e 60 meses. Houveram piores taxas para o paciente etilista e com recidiva.Conclusão:A presença do HPV não se mostrou importante, como fator prognóstico, nessa série cirúrgica se o paciente for etilista e ou tabagista<br>Introduction:Oropharynx cancer is considered to enact approximately 10 to 12% of the cases among all malignant tumors from the upper aero digestive tract showing significant growth in its frequency rate in The United States and Europe. Human papillomavirus (HPV) is associated to oropharynx cancer in up to 63% of the cases, promoting better evolution and prognostic.Objective:Describe the prevalence of the HPV in oropharynx squamous cells carcinoma submitted to surgery. Investigate the association between HPV presence and the demographic, clinical, pathologic and therapeutic features. Estimate the importance of the HPV existence on the diseasefree survival and overall survival. Material andMethods: The existence of Human papillomavirus was studied through the use of PCR. The sample account was conducted through average, absolute and relative frequency. It has been estimated the prevalence of HPV and its corresponding 95% confidence interval. The association analysis between the presence of HPV and the demographic, clinical and pathological features was completed by the Qui-square association test. The disease-free survival timeline and the overall survival were estimated using the product limit estimator Kaplan-Meier and Cox proportional hazards model. Results: The studied patients were aged between 34 and 78, showing an average of 56.9 years of age. There were only 10 women in the study, thus presenting 76 men. Most of the patients were white (83.7%). It has been ascertained that 69.0% of the patients presented the symptoms onset up to the sixth month of the disease. The most common symptom among 38.4% of the cases was odinophagy. In regards to the tumor location 69.8% were found in the amygdala.Clinical stagings III and IV were found to be the ones with greater representation among patients (71.4%). Extensive surgeries such as bucopharyngectomy were performed in 76 patients (88.4%). In order to treat ipsilateral neck 81 patients underwent neck dissection (94.2%). Contralateral neck dissection was applied in 21 patients (24.4%). The prevalence of HPV was of 57%, and the most common type was 16, present in 83.6% of the cases. It was possible to notice smoking as the only statistically significant association, which showed all nonsmoking having HPV. The disease-free survival rates were of 73.9%, 65.9% and 57.9% to 12, 24 and 60 months respectively. The study has shown significant statistical difference with worse rates, to the ones under 55 years of age and presenting compromised margins. HPV presence did not influence the disease-free survival timeline, or the overall survival. The overall survival rates were of 75.6%, 54.7% and 43.0% to 12, 24 and 60 months respectively. Worse rates were found in alcoholic patients as well as in relapse cases. Conclusion: In these surgical series, HPV existence was not identified as an important prognosis factor when considering smokers and/or alcoholic patients
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Higa, Laurinda Yoko Shinzato. "Sobrevivência e fatores de risco para mortalidade identificados ao diagnóstico na coorte de pacientes com fibrose cística do centro de referência do Rio de Janeiro (Brasil)." Instituto Fernandes Figueira, 2011. https://www.arca.fiocruz.br/handle/icict/6435.
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Previous issue date: 2011<br>Fundação Oswaldo Cruz. Instituto Fernandes Figueira. Departamento de Ensino. Programa de Pós-Graduação em Saúde da Criança e da Mulher. Rio de Janeiro, RJ, Brasil<br>Introdução: A fibrose cística (FC) é uma doença genética, de transmissão
autossômica recessiva, que compromete múltiplos órgãos, que apresenta curso
crônico e progressivo sendo considerada potencialmente letal.
Objetivos: Estimar a sobrevivência dos pacientes com FC e os fatores de risco
associados à redução no tempo de sobrevivência.
Métodos: Tratou-se de uma coorte aberta de casos diagnosticados entre
01/01/1990 e 10/10/2009 no Centro de Referência em FC do RJ, CRFC-RJ,
Brasil na qual se analisou a sobrevivência global e fatores de risco associados
com a sobrevida dos pacientes. O período de risco iniciou-se na idade ao
diagnóstico e terminou na idade quando ocorreu o óbito por FC, a perda de
seguimento ou o fim do estudo. Os fatores analisados foram: sexo, motivo da
suspeita diagnóstica, genótipo, número de órgãos comprometidos, estado
nutricional, colonização bacteriana, reposição enzimática e década do
diagnóstico. As curvas de sobrevivência foram estimadas pelo método Kaplan-
Meier, ajustadas para truncamento à esquerda e para dados censurados à
direita. A seguir, as hazard ratios (HR) foram estimadas pelo modelo de Cox,
utilizando o processo de contagem, tendo a idade como escala de tempo e
avaliadas pelo teste de razão de verossimilhança, e os modelos comparados
pela análise de resíduos.
Resultados: A população (n=177) apresentou o predomínio do sexo feminino
(56%) e a idade mediana ao diagnóstico foi 14 meses. A idade mediana de
sobrevivência foi 20,8 anos. Após o diagnóstico 81% sobreviveram até cinco
anos; 70% até 10 anos e 61% até 14,5 anos. O modelo explicou 19,9% dos
efeitos e incluiu seis covariáveis: colonização por Pseudomonas aeruginosa,
isolada e associada (HR = 10,30; IC95% = 2,41-43,97), por Staphylococcus
aureus (HR=4,50; IC95% = 0,93-1,85), por outras bactérias (HR=3,38; IC95% =
0,92-1,32), sexo feminino (HR=1,95; IC95% = 0,96-3,96), estado nutricional ≤
p5 (HR=1,94; IC95% = 0,94-3,98) e diagnóstico na década de 1990 (HR=4,34;
IC95% = 1,50-12,52).
Conclusão: Este estudo de coorte de 177 pacientes com FC mostrou uma
idade mediana de sobrevivência de 20,8 anos dos pacientes no CRFC-RJ.
Foram confirmados os efeitos das covariáveis que, presentes ao diagnóstico,
se associaram a maior mortalidade. A intervenção nestas covariáveis
promoverá a recuperação nutricional, a erradicação da Pseudomonas
aeruginosa ou o adiamento da colonização crônica, dessa forma aumentando a
sobrevivência.<br>Introduction: Cystic Fibrosis (CF) is a rare genetic disease, of autossomal
recessive transmission, with multiple organ involvement, progressive course
and potentially lethal.
Objective: To study the CF patients survival and to find the factors associated
with.
Methods: In an open cohort of cases diagnosed between 01/01/1990 and
10/10/2009 in a CF reference center in Rio de Janeiro, we analyzed global
survival and risk factors associated with the survival of CF patients. The at-risk
period started at the age of CF diagnosis and ended at age of death, loss of
follow-up or end of the study. The factors analyzed were gender, presentation
mode, genotype, number of involved organs, nutritional state, bacterial
colonization, enzyme replacement and decade of diagnosis. Survival curves
were estimated by Kaplan-Meier (KM) adjusted for left truncation and right
censored data. Hazard ratios (HR) were estimated by Cox model using counting
process approach with age as time scale and evaluated by likelihood ratio test.
Model diagnostic was conducted by residuals analysis.
Results: The majority of the population (n=177) was female (56%) and during
the study the median age at diagnosis was 14 months. The median survival was
of 20.8 years. After diagnosis, 81% survived up to 5 years, 70% up to 10 and
61% up to 14.5. The model explained 19.9% of the effects and included six
covariates: Pseudomonas aeruginosa colonization, isolated or associated (HR =
10.30; 95%CI = 2.41-43.97), for Staphylococcus aureus (HR = 4.50; CI95% =
0.93-1.85), for other bacteria (HR = 3.38; CI95% = 0.92-1.32), for female gender
(HR = 1.95; CI95% = 0.96-3.96), for nutritional state ≤ p5 (HR = 1.94; CI95% =
0.94-3.98), and for diagnostic decade (HR = 4.34; CI95% = 1.50-12.52).
Conclusion: The strength of risk factors found at diagnosis was evident in the
prognosis besides indicating that interventions may reduce morbidity by
nutritional recovery and by Pseudomonas aeruginosa eradication thus
increasing survival.
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Müller, Regina Elizabeth. "Cardiopatia reumática com lesão valvar em crianças e adolescentes: fatores associados ao tempo até a terapêutica cirúrgica." Instituto Nacional de Saúde da Mulher, da Criança e do Adolescente Fernandes Figueira, 2011. https://www.arca.fiocruz.br/handle/icict/8042.
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Previous issue date: 2011<br>Fundação Oswaldo Cruz. Instituto Nacional de Saúde da Mulher, da Criança e do Adolescente Fernandes Figueira. Rio de Janeiro, RJ, Brasil.<br>Introdução: A cardiopatia reumática persiste como a principal doença cardiovascular adquirida em crianças e adultos jovens em todo o mundo, sendo responsável por altas taxas de morbimortalidade e evoluindo com frequência para a necessidade de cirurgia cardíaca valvar em pacientes na fase aguda ou crônica da doença.
Objetivo: Estimar os fatores associados e o tempo desde o diagnóstico até a cirurgia cardíaca valvar em crianças e adolescentes portadores de cardiopatia reumática, em um centro cardiológico de referência terciária no Rio de Janeiro.
Material e Métodos: estudo observacional longitudinal de base hospitalar, utilizando metodologia de análise de sobrevivência, para estimativa do tempo até a cirurgia, e modelo de regressão de Cox, para avaliar as razões de risco associadas segundo as covariáveis. A coorte foi composta por pacientes com 3 a 20 anos, cadastrados no Instituto Nacional de Cardiologia no Rio de Janeiro entre julho de 1986 e junho de 2006 e acompanhados até setembro de 2011. O diagnóstico da lesão valvar foi confirmado pelo exame Doppler-ecocardiográfico. As covariáveis, avaliadas no início do acompanhamento, foram reunidas em três dimensões: sociodemográfica (sexo, grupo etário, cor da pele, região de moradia e década do diagnóstico); clínica (apresentação clínica, classe funcional, número de surtos anteriores, profilaxia secundária, endocardite infecciosa e fibrilação atrial); e ecocardiográfica (lesão valvar por tipo e gravidade; diâmetro do átrio esquerdo, diâmetro sistólico do ventrículo esquerdo, função ventricular esquerda, hipertensão arterial pulmonar, e ruptura de cordoalha mitral). O banco de dados foi elaborado com o programa ACCESS 2000 e a análise estatística foi realizada pelo programa R versão 2.13.1. Foi considerado significativo o valor de - 0,05.
Resultados: a coorte foi composta por 348 pacientes, 58% do sexo feminino, com idade mediana ao cadastro de 12,5 anos, e de 21,5 anos ao final do acompanhamento. O tempo médio de seguimento foi de 9,0 anos (2-21 anos). O evento cirurgia cardíaca ocorreu em 39% da amostra, com tempo mediano até a cirurgia de 22,3 anos. Na análise univariada todas as covariáveis das três dimensões (socioedemográfica, clínica e ecocardiográfica) apresentaram significância estatística e risco para realização de cirurgia cardíaca (hazard ratio>1), com exceção apenas da covariável região de moradia (p>0,5). Na análise multivariada, o modelo final incluiu as variáveis: década do diagnóstico, classe funcional, número de surtos anteriores, endocardite infecciosa, lesão valvar por tipo e gravidade, diâmetro do átrio esquerdo, diâmetro sistólico do ventrículo esquerdo e ruptura de cordoalha mitral.
Conclusões: A realização da cirurgia cardíaca em pacientes com cardiopatia reumática está associada a fatores sociodemográficos, clínicos e ecocardiográficos.<br>Introduction: Rheumatic heart disease remains as the most common acquired heart disease in children and young adults all over the world, being responsible for high mortality and morbidity rates and often demanding valve surgery in the acute or chronic phase of the disease.
Objective: To estimate the time from diagnosis until valve operation and the associated factors in children and young adults with rheumatic heart disease followed up in a tertiary center for cardiovascular care in Rio de Janeiro.
Methods – It is a longitudinal observational study of a hospital based population, using survival analysis methodology for time estimation and Cox regression model for hazard risk evaluation of associated variables. Cohort was composed by 3 to 20 years old patients, registered in the National Institute of Cardiology (Instituto Nacional de Cardiologia), in Rio de Janeiro, between July 1986 and June 2006, and followed up until September 2011. Valve disease diagnosis was confirmed through Doppler echocardiography examination. Variables were evaluated at the patient´s first visit and separated in three dimensions: socio demographic (gender, age group, skin color, residence region, decade of diagnosis); clinic (disease status at presentation, functional class, number of previous rheumatic episodes, secondary prophylaxis, infectious endocarditis, atrial fibrillation); echocardiographic (valve lesion and severity, left atrium diameter, systolic left ventricle diameter, left ventricle function, pulmonary hypertension, rupture of mitral chordae). The database wasbased on the program ACCESS 2000 and statistical analysis was performed using the R Program version 2.13.1. For statistical analysis was considered as significant values for value 0.05.
Results – 348 patients were included in the cohort, 58% female. Median age at the register was 12.5 years, and 21.5 years at the end of follow up. Median follow-up time was 9.0 years (2 to 21 years). 39% underwent valve operation and the median time until surgery was 22.3 years. In the univariate analysis all the variables from the three dimensions (socio demographic, clinic and echocardiographic) presented statistical significance as hazard risk in predicting valve operation (hazard ratio>1), with only one exception, that was residence region (p>0.5). In the multivariate analysis the final model included the following variables: decade of diagnosis, functional class, number of anterior rheumatic episodes, infectious endocarditis, valve lesion and severity, left atrium diameter, systolic left ventricle diameter and rupture of mitral chordate.
Conclusions: Valve surgery in patients with rheumatic heart disease is associated with socio demographic, clinic and echocardiographic factors.
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Fontenelle, OtÃvio Fernandes. "Survival Analysis; Micro and Small Enterprises; Modeling Survival Data, Data Characterization Survival; parametric Estimator KAPLAN-MEIER." Universidade Federal do CearÃ, 2009. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=4173.
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nÃo hÃ<br>The main objective of this research is to explore economics issues that may induce impact on lifetime of small businesses during 2002 to 2006. The group of enterprises studied was selected from database of taxpayers recorded at fiscal authority of State of CearÃ. To do that,
the methodology was focused on a branch of statistics which deals with survival analysis, called duration analysis or duration modeling in economics. It was applied non-linear model whose non-parametric estimator chosen was KAPLAN-MEIER. Through that methodology, it was developed sceneries based on the following attributes: county where the enterprises were established; economics activities based on national classification, fiscal version 1.0/1.1; and,
finally, the relationship between State of Cearà â as fiscal authority â and enterprises. The counties were grouped applying two parameters of stratifications: gross domestic product(GDP) per capita and investment in education per capita. Before any stratification, only
counties with thirty or more enterprises starting their activities in year 2002 were considered in sceneries to analysis.<br>A dissertaÃÃo tem o objetivo de investigar fatores econÃmicos que possam influenciar na sobrevida de micros e pequenas empresas (MEPs) contribuintes do Imposto sobre OperaÃÃes
relativas à CirculaÃÃo de Mercadorias e sobre PrestaÃÃes de ServiÃos de Transporte Interestadual e Intermunicipal e de ComunicaÃÃo (ICMS) do Estado do Cearà no perÃodo de
2002 Ã 2006. Para isso, aplicou-se uma tÃcnica estatÃstica denominada anÃlise de sobrevivÃncia a partir de modelos nÃo lineares cujo estimador nÃo-paramÃtrico escolhido foi o
de KAPLAN-MEIER. Com os dados de sobrevivÃncia devidamente modelados, buscou-se estratificÃ-los focando os municÃpios dos logradouros das MEPs; dentro do que tange as
operaÃÃes do ICMS, focando as atividades econÃmicas segundo a classificaÃÃo nacional de atividades econÃmicas (CNAE) versÃo fiscal 1.0/1.1; e, finalmente, observar a relaÃÃo do Estado â enquanto autoridade fiscal â com esses pequenos estabelecimentos, restringindo temporariamente seu faturamento ou mesmo baixando sua inscriÃÃo estadual,
impossibilitando a continuidade de suas atividades. Dos municÃpios, utilizou-se como Ãndice de estratificaÃÃo entre as curvas de sobrevivÃncia o produto interno bruto (PIB) per capita e os investimentos mÃdio per capita em educaÃÃo daquelas empresas localizadas em municÃpios com 30 ou mais estabelecimentos ativados no ano de 2002. Dentre outras, duas importantes observaÃÃes foram identificar o municÃpio de Fortaleza como um âoutlinerâ frente aos outros municÃpios e a forte dominÃncia da curva de sobrevivÃncia das empresas que nÃo sofreram intervenÃÃo do fisco em suas atividades sobre aquelas que tiveram.
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Caetano, Sabrina Luzia [UNESP]. "Estudo da idade da vaca ao último parto para avaliar longevidade em rebanhos da raça nelore por análise de sobrevivência." Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/102783.
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caetano_sl_dr_jabo.pdf: 775583 bytes, checksum: a57f6e271b7d34656d680987f933ba7d (MD5)<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)<br>Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)<br>No Brasil, existem poucos estudos sobre longevidade de vacas de corte, principalmente utilizando ferramentas de análise de sobrevivência na estimação de parâmetros genéticos. Todavia, os critérios para avaliar esta característica são vários, tal que em alguns destes nem todos os registros das vacas nos rebanhos podem ser levados em consideração, devido à metodologia de análise utilizada. Uma variável que é de fácil mensuração e já faz parte da maioria dos controles zootécnicos das fazendas é a idade da vaca ao último parto (IVUP). Neste trabalho, objetivo foi avaliar a longevidade das vacas nos rebanhos utilizando a variável IVUP, por meio da metodologia de análise de sobrevivência. Esta variável foi utilizada mediante um critério para analisar a longevidade produtiva de vacas nos rebanhos. O critério adotado foi a diferença entre a data em relação ao último parto de cada vaca e a data do último parto de cada fazenda. Se esta diferença foi superior a 36 meses, a vaca falhou e foi considerada descartada. Caso contrário, esta vaca foi censurada, indicando que esta ainda poderia ter futuras parições. O critério de 36 meses foi proposto por ser período suficiente para a ocorrência de um novo parto. A metodologia de análise de sobrevivência foi utilizada por considerar dados censurados e não censurados. As variáveis: estação e ano de nascimento de cada vaca, a fazenda e a idade ao primeiro parto foram utilizadas para as análises da variável IVUP. Um estudo prévio por meio de curvas de Kaplan-Meier e o modelo de Cox, utilizando a distribuição gama para os touros, desconsiderando o parentesco entre eles, foram realizados. O software Survival Kit foi empregado para estimação dos parâmetros genéticos, levando em consideração o parentesco entre os animais. Verificou-se que a IVUP apresentou herdabilidade de 0,25, e que seu uso permite avaliar a...<br>In Brazil, there are few studies about stayability, especially using tools of survival analysis in the estimation of breeding values and heritability. The criteria for evaluating this characteristic are different, such that in some of these not all information in the herds of cows can be taken into consideration, because the method of analysis used. In addition, the definitions that consider the date of disposal of the animal affect the use of information obtained in practice, because until the cows come out of the flock may take years, thus the evaluation of their parents is impaired, since the goal is selection. A variable that is easy to measure and is already part of most controls husbandry farms are cow age at last birth (IVUP). This variable was used by one criterion to analyze the productive longevity of cows in herds. The criterion was the difference between the date from the last delivery date of each cow and the last part of each farm. If this difference was more than 36 months, the cow was considered failed and discarded. Otherwise, this cow was censored, indicating that this could still have further parities. The criterion of 36 months was proposed to be sufficient time for the occurrence of a new birth. The methodology of survival analysis was used. The variables season and year of birth of each cow, farm and age at first birth were used for analysis of variable IVUP. The objective of this study was to evaluate the performance of the variable IVUP through estimates of genetic and fixed effect, to study the longevity of cows in the herd. A previous study by Kaplan-Meier and Cox model using the gamma distribution for the bulls, disregarding the relationship between them, were performed. The Survival Kit software was used to estimate the genetic parameters, taking into account the relationship between the animals. It was found that the heritability of 0.25 for IVUP ... (Complete abstract click electronic access below)
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Rasteiro, Louise Rossi. "Regressão quantílica para dados censurados." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/45/45133/tde-09072017-141021/.
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A regressão quantílica para dados censurados é uma extensão dos modelos de regressão quantílica que, por levar em consideração a informação das observações censuradas na modelagem, e por apresentar propriedades bastante satisfatórias, pode ser vista como uma abordagem complementar às metodologias tradicionais em Análise de Sobrevivência, com a vantagem de permitir que as conclusões inferenciais sejam tomadas facilmente em relação aos tempos de sobrevivência propriamente ditos, e não em relação à taxa de riscos ou a uma função desse tempo. Além disso, em alguns casos, pode ser vista também como metodologia alternativa aos modelos clássicos quando as suposições destes são violadas ou quando os dados são heterogêneos. Apresentam-se nesta dissertação três técnicas para modelagem com regressão quantílica para dados censurados, que se diferenciam em relação às suas suposições e forma de estimação dos parâmetros. Um estudo de simulação para comparação das três técnicas para dados com distribuição normal, Weibull e log-logística é apresentado, em que são avaliados viés, erro padrão e erro quadrático médio. São discutidas as vantagens e desvantagens de cada uma das técnicas e uma delas é aplicada a um conjunto de dados reais do Instituto do Coração do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo.<br>Censored quantile regression is an extension of quantile regression, and because it incorporates information from censored data in the modelling, and presents quite satisfactory properties, this class of models can be seen as a complementary approach to the traditional methods in Survival Analysis, with the advantage of allowing inferential conclusions to be made easily in terms of survival times rather than in terms of risk rates or as functions of survival time. Moreover, in some cases, it can also be seen as an alternative methodology to the classical models when their assumptions are violated or when modelling heterogeneity of the data. This dissertation presents three techniques for modelling censored quantile regression, which differ by assumptions and parameter estimation method. A simulation study designed with normal, Weibull and loglogistic distribution is presented to evaluate bias, standard error and mean square error. The advantages and disadvantages of each of the three techniques are then discussed and one of them is applied to a real data set from the Heart Institute of Hospital das Clínicas, University of São Paulo.
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Guedes, Deborah Galv?o Peixoto. "Avalia??o gen?tica da efici?ncia reprodutiva em vacas pardo-su??as por meio da an?lise de sobreviv?ncia." Universidade Federal do Rio Grande do Norte, 2014. http://repositorio.ufrn.br:8080/jspui/handle/123456789/17188.
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Previous issue date: 2014-02-20<br>Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior<br>Among the traits of economic importance to dairy cattle livestock those related to sexual precocity and longevity of the herd are essential to the success of the activity, because the stayability time of a cow in a herd is determined by their productive and reproductive lives. In Brazil, there are few studies about the reproductive efficiency of Swiss-Brown cows and no study was found using the methodology of survival analysis applied to this breed. Thus, in the first chapter of this study, the age at first calving from Swiss-Brown heifers was analyzed as the time until the event by the nonparametric method of Kaplan-Meier and the gamma shared frailty model, under the survival analysis methodology. Survival and hazard rate curves associated with this event were estimated and identified the influence of covariates on such time. The mean and median times at the first calving were 987.77 and 1,003 days, respectively, and significant covariates by the Log-Rank test, through Kaplan-Meier analysis, were birth season, calving year, sire (cow s father) and calving season. In the analysis by frailty model, the breeding values and the frailties of the sires (fathers) for the calving were predicted modeling the risk function of each cow as a function of the birth season as fixed covariate and sire as random covariate. The frailty followed the gamma distribution. Sires with high and positive breeding values possess high frailties, what means shorter survival time of their daughters to the event, i.e., reduction in the age at first calving of them. The second chapter aimed to evaluate the longevity of dairy cows using the nonparametric Kaplan-Meier and the Cox and Weibull proportional hazards models. It were simulated 10,000 records of the longevity trait from Brown-Swiss cows involving their respective times until the occurrence of five consecutive calvings (event), considered here as typical of a long-lived cow. The covariates considered in the database were age at first calving, herd and sire (cow s father). All covariates had influence on the longevity of cows by Log-Rank and Wilcoxon tests. The mean and median times to the occurrence of the event were 2,436.285 and 2,437 days, respectively. Sires that have higher breeding values also have a greater risk of that their daughters reach the five consecutive calvings until 84 months<br>Dentre as caracter?sticas de import?ncia econ?mica para a pecu?ria leiteira aquelas relacionadas com a precocidade sexual e a longevidade do rebanho s?o determinantes para o sucesso da atividade, uma vez que o tempo de perman?ncia de uma vaca num rebanho ? determinado por suas vidas produtiva e reprodutiva. No Brasil, existem poucos estudos sobre a efici?ncia reprodutiva de vacas Pardo-Su??as e n?o foi encontrado nenhum estudo abordando o uso da metodologia de an?lise de sobreviv?ncia aplicada a esta ra?a. Assim, no primeiro cap?tulo deste trabalho, a idade ao primeiro parto de novilhas Pardo-Su??as foi analisada como o tempo at? o evento por meio do m?todo n?o-param?trico de Kaplan-Meier e do modelo de fragilidade compartilhado gama, sob a metodologia de an?lise de sobreviv?ncia. Foram estimadas curvas de sobreviv?ncia e de taxa de risco associadas com este evento e verificada a influ?ncia das covari?veis consideradas sobre o tempo. Os tempos m?dio e mediano ao primeiro parto foram 987,77 e 1.003 dias, respectivamente; e as covari?veis significativas pelo teste de Log-Rank, na an?lise por Kaplan-Meier, foram esta??o de nascimento, ano de parto, touro (pai da vaca) e esta??o de parto. Na an?lise pelo modelo de fragilidade, foram preditos os valores gen?ticos e as fragilidades dos touros (pais) para o parto, modelando-se a fun??o de risco de cada vaca em fun??o da covari?vel fixa esta??o de nascimento e da covari?vel aleat?ria touro. A fragilidade seguiu a distribui??o gama. Touros com valores gen?ticos positivos e altos possuem fragilidades altas, o que significa menor tempo de sobreviv?ncia de suas filhas ao evento, ou seja, redu??o na idade ao primeiro parto delas. O segundo cap?tulo teve como objetivo avaliar a longevidade de vacas leiteiras utilizando o estimador n?o-param?trico de Kaplan-Meier e os modelos de riscos proporcionais de Weibull e de Cox. Foram simulados 10.000 registros da caracter?stica longevidade de f?meas Pardo-Su??as denotando seus respectivos tempos at? a ocorr?ncia de cinco partos consecutivos (evento), considerados aqui como t?picos de uma vaca longeva. As covari?veis consideradas no banco de dados foram a idade da vaca ao primeiro parto, o rebanho e o pai da vaca. Todas as covari?veis exerceram influ?ncia sobre a longevidade das vacas de acordo com os testes de Log-Rank e Wilcoxon. Os tempos m?dio e mediano para a ocorr?ncia do evento foram de 2.436,285 e 2.437 dias. Touros com maior valor gen?tico tamb?m possuem um maior risco de que as suas filhas alcancem os cinco partos aos 84 meses
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Horrigue, Walid. "Prévision non paramétrique dans les modèles de censure via l'estimation du quantile conditionnel en dimension infinie." Thesis, Littoral, 2012. http://www.theses.fr/2012DUNK0511.
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Dans cette thèse, nous étudions les propriétés asymptotiques de paramètres fonctionnels conditionnels en statistique non paramétrique, quand la variable explicative prend ses valeurs dans un espace de dimension infinie. Dans ce cadre non paramétrique, on considère les estimateurs des paramètres fonctionnels usuels, tels la loi conditionnelle, la densité de probabilité conditionnelle, ainsi que le quantile conditionnel. Le premier travail consiste à proposer un estimateur du quantile conditionnel et de prouver sa convergence uniforme sur un sous-ensemble compact. Afin de suivre la convention dans les études biomédicales, nous considérons une suite de v.a {Ti, i ≥ 1} identiquement distribuées, de densité f, censurée à droite par une suite aléatoire {Ci, i ≥ 1} supposée aussi indépendante, identiquement distribuée et indépendante de {Ti, i ≥ 1}. Notre étude porte sur des données fortement mélangeantes et X la covariable prend des valeurs dans un espace à dimension infinie.Le second travail consiste à établir la normalité asymptotique de l’estimateur à noyau du quantile conditionnel convenablement normalisé, pour des données fortement mélangeantes, et repose sur la probabilité de petites boules. Plusieurs applications à des cas particuliers ont été traitées. Enfin, nos résultats sont appliqués à des données simulées et montrent la qualité de notre estimateur<br>In this thesis, we study some asymptotic properties of conditional functional parameters in nonparametric statistics setting, when the explanatory variable takes its values in infinite dimension space. In this nonparametric setting, we consider the estimators of the usual functional parameters, as the conditional law, the conditional probability density, the conditional quantile. We are essentially interested in the problem of forecasting in the nonparametric conditional models, when the data are functional random variables. Firstly, we propose an estimator of the conditional quantile and we establish its uniform strong convergence with rates over a compact subset. To follow the convention in biomedical studies, we consider an identically distributed sequence {Ti, i ≥ 1}, here density f, right censored by a random {Ci, i ≥ 1} also assumed independent identically distributed and independent of {Ti, i ≥ 1}. Our study focuses on dependent data and the covariate X takes values in an infinite space dimension. In a second step we establish the asymptotic normality of the kernel estimator of the conditional quantile, under α-mixing assumption and on the concentration properties on small balls of the probability measure of the functional regressors. Many applications in some particular cases have been also given
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Li, Weiyu. "Quelques contributions à l'estimation des modèles définis par des équations estimantes conditionnelles." Thesis, Rennes 1, 2015. http://www.theses.fr/2015REN1S065/document.
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Dans cette thèse, nous étudions des modèles définis par des équations de moments conditionnels. Une grande partie de modèles statistiques (régressions, régressions quantiles, modèles de transformations, modèles à variables instrumentales, etc.) peuvent se définir sous cette forme. Nous nous intéressons au cas des modèles avec un paramètre à estimer de dimension finie, ainsi qu’au cas des modèles semi paramétriques nécessitant l’estimation d’un paramètre de dimension finie et d’un paramètre de dimension infinie. Dans la classe des modèles semi paramétriques étudiés, nous nous concentrons sur les modèles à direction révélatrice unique qui réalisent un compromis entre une modélisation paramétrique simple et précise, mais trop rigide et donc exposée à une erreur de modèle, et l’estimation non paramétrique, très flexible mais souffrant du fléau de la dimension. En particulier, nous étudions ces modèles semi paramétriques en présence de censure aléatoire. Le fil conducteur de notre étude est un contraste sous la forme d’une U-statistique, qui permet d’estimer les paramètres inconnus dans des modèles généraux<br>In this dissertation we study statistical models defined by condition estimating equations. Many statistical models could be stated under this form (mean regression, quantile regression, transformation models, instrumental variable models, etc.). We consider models with finite dimensional unknown parameter, as well as semiparametric models involving an additional infinite dimensional parameter. In the latter case, we focus on single-index models that realize an appealing compromise between parametric specifications, simple and leading to accurate estimates, but too restrictive and likely misspecified, and the nonparametric approaches, flexible but suffering from the curse of dimensionality. In particular, we study the single-index models in the presence of random censoring. The guiding line of our study is a U-statistics which allows to estimate the unknown parameters in a wide spectrum of models
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Serasinghe, Shyamalee Kumary. "A simulation comparison of parametric and nonparametric estimators of quantiles from right censored data." Kansas State University, 2010. http://hdl.handle.net/2097/4318.
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Master of Science<br>Department of Statistics<br>Paul I. Nelson<br>Quantiles are useful in describing distributions of component lifetimes. Data, consisting
of the lifetimes of sample units, used to estimate quantiles are often censored. Right censoring,
the setting investigated here, occurs, for example, when some test units may still be functioning
when the experiment is terminated. This study investigated and compared the performance of
parametric and nonparametric estimators of quantiles from right censored data generated from
Weibull and Lognormal distributions, models which are commonly used in analyzing lifetime
data. Parametric quantile estimators based on these assumed models were compared via
simulation to each other and to quantile estimators obtained from the nonparametric Kaplan-
Meier Estimator of the survival function. Various combinations of quantiles, censoring
proportion, sample size, and distributions were considered.
Our simulation show that the larger the sample size and the lower the censoring rate the
better the performance of the estimates of the 5th percentile of Weibull data. The lognormal data
are very sensitive to the censoring rate and we observed that for higher censoring rates the
incorrect parametric estimates perform the best.
If you do not know the underlying distribution of the data, it is risky to use parametric
estimates of quantiles close to one. A limitation in using the nonparametric estimator of large
quantiles is their instability when the censoring rate is high and the largest observations are
censored.
Key Words: Quantiles, Right Censoring, Kaplan-Meier estimator
Books on the topic "Kaplan-Meier Estimate"
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Peacock, Janet L., and Sally M. Kerry. Survival analysis. Oxford University Press, 2013. http://dx.doi.org/10.1093/med/9780198599661.003.0011.
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Peacock, Janet L., Sally M. Kerry, and Raymond R. Balise. Survival analysis. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780198779100.003.0011.
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Chapter 11 covers survival analysis, and includes Kaplan–Meier estimates, and the logrank test. Cox regression is used to do multifactorial analyses with results reported as adjusted hazard ratios. The chapter includes analyses using Stata, SAS, SPSS, and R.
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Luo, Dali. Some properties of the Kaplan-Meier estimator and a method to find system reliability. 1992.
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Cheng, Russell. Change-Point Models. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198505044.003.0011.
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This chapter investigates change-point (hazard rate) probability models for the random survival time in some population of interest. A parametric probability distribution is assumed with parameters to be estimated from a sample of observed survival times. If a change-point parameter, denoted by τ, is included to represent the time at which there is a discrete change in hazard rate, then the model is non-standard. The profile log-likelihood, with τ as profiling parameter, has a discontinuous jump at every τ equal to a sampled value, becoming unbounded as τ tends to the largest observation. It is known that maximum likelihood estimation can still be used provided the range of τ is restricted. It is shown that the alternative maximum product of spacings method is consistent without restriction on τ. Censored observations which commonly occur in survival-time data can be accounted for using Kaplan-Meier estimation. A real data numerical example is given.
Book chapters on the topic "Kaplan-Meier Estimate"
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Gijbels, Irène. "Kaplan-Meier Estimator." In International Encyclopedia of Statistical Science. Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-04898-2_322.
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Meira-Machado, Luís. "The Kaplan-Meier Estimator: New Insights and Applications in Multi-state Survival Analysis." In Computational Science and Its Applications – ICCSA 2023 Workshops. Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-37129-5_11.
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Eswar Reddy, R., and K. Santhi. "The Survival Analysis of Mental Fatigue Utilizing the Estimator of Kaplan-Meier and Nelson-Aalen." In Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering. Springer Nature Switzerland, 2024. http://dx.doi.org/10.1007/978-3-031-48888-7_19.
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Tang, Xinyu. "Kaplan–Meier Estimator." In Handbook for Clinical Research. Springer Publishing Company, 2014. http://dx.doi.org/10.1891/9781617050992.0040.
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Jiang, Hongyu, and Jason Fine. "Kaplan–Meier Estimator." In Encyclopedia of Biopharmaceutical Statistics, Second edition. CRC Press, 2003. http://dx.doi.org/10.1201/b14760-78.
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Jiang, Hongyu, and Jason Fine. "Kaplan–Meier Estimator." In Encyclopedia of Biopharmaceutical Statistics, Third Edition. CRC Press, 2012. http://dx.doi.org/10.1201/b14674-112.
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Jiang, Hongyu, and Jason Fine. "Kaplan–Meier Estimator." In Encyclopedia of Biopharmaceutical Statistics. Informa Healthcare, 2010. http://dx.doi.org/10.3109/9781439822463.111.
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Cubaynes, Sarah, Simon Galas, Myriam Richaud, et al. "Survival analyses." In Demographic Methods across the Tree of Life. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198838609.003.0013.
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Survival analyses are a key tool for demographers, ecologists, and evolutionary biologists. This chapter presents the most common methods and illustrates their use for species across the Tree of Life. It discusses the challenges associated with various types of survival data, how to model species with a complex life cycle, and includes the impact of environmental factors and individual heterogeneity. It covers the analysis of ‘known-fate’ data collected in lab conditions, using the Kaplan–Meier estimator and Cox’s proportional hazard regression analysis. Alternatively, survival data collected on free-ranging populations usually involve individuals missing at certain monitoring occasions and unknown time at death. The chapter provides an overview of capture–mark–recapture (CMR) models, from single-state to multi-state and multi-event models, and their use in animal and plant demography to estimate demographic parameters while correcting for imperfect detection of individuals. It discusses various inference frameworks available to implement CMR models using a frequentist or Bayesian approach. Only humans are an exception among free-ranging populations, with the existence of several consequent databases with perfect knowledge of age and cause of death for all individuals. The chapter presents an overview of the most common models used to describe mortality patterns over age and time using human mortality data. Throughout, focus is placed on eight case studies, which involve lab organisms, free-ranging animal populations, plant populations, and human populations. Each example includes data and codes, together with step-by-step guidance to run the survival analysis.
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"Kaplan–Meier Product Limit Estimator." In Encyclopedia of Cancer. Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-662-46875-3_101277.
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"Kaplan–Meier Product Limit Estimator." In Encyclopedia of Cancer. Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-16483-5_3195.
Full textConference papers on the topic "Kaplan-Meier Estimate"
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Pişkin, Erhan. "The Matter of Trade Survival." In International Conference on Eurasian Economies. Eurasian Economists Association, 2017. http://dx.doi.org/10.36880/c08.01879.
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Besedes and Prusa (2006a-b) reveal that international trade relationships are often very short-lived contrary to previously thoughts. In line with this unexpected result, this study provides a statistical description and empirical analysis of the duration of Turkish exports. Specifically, Kaplan-Meier survival function is used to estimate the survival of trade flows over time and also a regression analysis using discrete-time duration models which allow us to properly control for unobserved heterogeneity and the presence of many tied duration times is used to explore the impact of key variables on hazard rates of export flows. The detailed trade data reported by BACI-CEPII are employed to analyze Turkey's export to European Union countries from 1998 to 2013 according to the 6-digit Harmonized system. Results obtained from the analysis of descriptive statistics suggest that the duration of Turkey’s export to European Union countries is short-lived. The median and mean duration of Turkey's exports are merely two years and 4.26, respectively. The Kaplan-Meier estimates of survival functions show that all survival curves are downward sloping with decreasing rate and about 40% of export relationships fails in the first year. The results of the discrete-time duration models indicate that product-market diversification, common language, total exports, initial value, importer GDP and lagged duration have a strong negative impact on the hazard rates of export flows. Whereas distance, common border and difference in GDP per capita have a positive effect on the hazard rates of export flows.
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Jiang, Renyan. "A Bias-Corrected Kaplan-Meier Estimator." In 2020 Asia-Pacific International Symposium on Advanced Reliability and Maintenance Modeling (APARM). IEEE, 2020. http://dx.doi.org/10.1109/aparm49247.2020.9209357.
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Anurangi, P. A. L. A., D. Amaratunga, and S. D. Viswakula. "Testing For Group Differences in Proteomics Data with Left Censored Data and a Limited Sample Size." In SLIIT International Conference on Advancements in Sciences and Humanities 2023. Faculty of Humanities and Sciences, SLIIT, 2023. http://dx.doi.org/10.54389/kykw4210.
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This research study aims to assess how a specific treatment influences the levels of three proteins when left-censored observations are present in a limited sample size. The dataset contained paired data gathered from 20 subjects categorized into 4 groups with increasing dosages, collected before and after administrating the treatment. The primary objective of this study is to evaluate whether there is an increase in response with increasing dosage for each of the proteins. To check the adherence of data to standard distribution, Cumulative Distribution Function (CDF) plots were used. To obtain summary statistics, Regression on Order Statistics (ROS), Maximum Likelihood Estimate (MLE) and Kaplan-Meier (KM) methods were utilized. ROS assumed to be the estimate that generally works well for the dataset as KM was unable to estimate the median for highly censored data and MLE produced unrealistic values for mean in some cases. Various matched paired tests were used to assess differences between before treatment and after treatment. The censored sign test, censored sign rank test, Peto Prentice test, and censored paired test all produced consistent conclusions across different alternative hypotheses, confirming higher protein concentrations after treatment. To evaluate mean differences, censored ANOVA, permutation tests, Peto Peto test, and Kruskal Wallis test were employed. No method demonstrated clear superiority over others. Jonckheere Terpstra test revealed the presence of group trend across increasing dosages. Multiple detection limits did not significantly impact the conclusions drawn from the study, and their consideration did not pose additional burdens. In conclusion, the treatment had a significant effect on protein levels, with dose variations influencing the outcome.
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Ghosh, Ananya, Namrata Das, Sudip Mondal, and Srikanta Patnaik. "Kaplan-Meier Survival Estimator Analysis of Patient Data." In 2021 Smart City Challenges & Outcomes for Urban Transformation (SCOUT). IEEE, 2021. http://dx.doi.org/10.1109/scout54618.2021.00059.
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Teplanová, Patrícia, and Michal Závodný. "Use of the Kaplan-Meier Estimator in Actuarial Science." In EDAMBA 2022: 25th International Scientific Conference for Doctoral Students and Post-Doctoral Scholars. University of Economics in Bratislava, 2023. http://dx.doi.org/10.53465/edamba.2022.9788022550420.481-492.
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There are many reasons why an insured person lapses (cancels) his policy. Lapse risk is one of the main risks, which is also defined in Directive Solvency II. Lapse analysis can be performed by various statistical methods. In this paper, we illustrate the possibility of using survival analysis to calculate the lapse ratio. Survival analysis does not have to be used only in medical research but nowadays finds application also in economics e.g., actuarial science. We focus on the Kaplan-Meier estimator, the most used method of modeling survival times. In practice, not every insurance policy has to lapse, so survival times from these policies should be right-censored. The Kaplan-Meier method allows to include these censored observations in the model. We use R programming language to calculate Kaplan-Meier estimation for survival times and to plot survival functions. Since the Kaplan-Meier model is univariate model, we focus on the impact of sex on insurance policy lapses.
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Vazquez, Thais Perez, Rodrigo Gonçalves, Fernando Nalesso Aguiar, et al. "Analysis of the Magee 3 equation for assessing prognosis in breast cancer treatment." In Brazilian Breast Cancer Symposium 2024. Mastology, 2024. http://dx.doi.org/10.29289/259453942024v34s1035.
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Objective: In the treatment of breast cancer, along with molecular tests, tools such as Residual Cancer Burden (RCB) and Magee equations (ME) are used for prognosis. Linked to the OncotypeDX recurrence score, ME3 also predicts pathological complete response. Our objective is to evaluate the relationship of ME3 with overall survival (OS) and disease-free survival (DFS) and estimate the association between RCB and ME3. Methodology: This retrospective cohort study was carried out at the Cancer Institute of the State of São Paulo of the Hospital das Clínicas of the Faculty of Medicine of the University of São Paulo (ICESP/HCFMUSP) including patients with HER2-negative and HR-positive BC undergoing chemotherapy neoadjuvant treatment (NCT) from January 2011 to December 2017. OS and DFS analyses were performed using the Kaplan-Meier method and the log-rank test. ME3 scores were categorized into low (31). The association between these categories and the RCB categories was assessed using the chi-square test. Results: We enrolled 143 women (mean age: 50.3 years, range: 25–85 years). Pre-NCT, 55.2% had tumors >5 cm, and 35% had no axillary lymph node involvement (N0). The median OS time was 71.5 months, with a longer OS (43 months) observed for low ME3 values. A statistically significant association was found between ME3 and OS (HR=4.56, 95%CI 1.35–15.43, p=0.015), which was not observed for DFS (HR=2.33, 95%CI 1.06–5.13, p=0.036). Regarding RCB scores, 88.1% had moderate (RCB-II, 42.7%) or extensive (RCB-III, 45.4%) residual tumor burden. For ME3, 37.1% had a low value and 53.8% had an intermediate value. An inverse association was identified between RCB and ME3, a statistically significant relationship (χ2 =39.3215, p=0.000). Conclusion: ME3 demonstrated a statistically significant association with RCB and OS and could serve as an alternative to Oncotype Dx in resource-limited countries.
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Frederice, Ridania de Oliveira, Alan Andresson Lima Pereira, Felipe Eduardo Martins de Andrade, Samir Abdallah Hanna, Heloisa de Andrade Carvalho, and Gustavo Nader Marta. "DETERMINANTS OF SURVIVAL ON BRAZILIAN PATIENTS WITH BREAST CANCER IN PUBLIC AND PRIVATE PRACTICE." In Brazilian Breast Cancer Symposium 2022. Mastology, 2022. http://dx.doi.org/10.29289/259453942022v32s2021.
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Objective: The Brazilian health system can be divided into public and private sectors. In the public sector, insurance is provided by the state to all Brazilian citizens (municipal, state, and federal levels). The private sector is comprised of the private health insurance area, with various schemes of health plans or with out-of-pocket expenses. This study proposed to evaluate the breast cancer population characteristics and treatments according to public and private health care systems. Methods: This retrospective cohort study included patients diagnosed with invasive breast cancer, with health insurance information, between January 2000 and June 2020, from the Fundação Oncocentro de Sao Paulo database. Patients were described according to age, gender, level of education, histology of neoplasm, stage at diagnosis, and type of treatment. Categorical variables are described as percentages and frequencies. The association between demographic and treatment factors and overall survival (OS) was evaluated using a Cox proportional hazard (PH) regression model while accounting for different lengths of participant follow-up. Uni- and multivariable Cox PH models were used to estimate hazard ratios with corresponding 95% confidence intervals for OS. The Kaplan-Meier (KM) curves were used to visually display survival curves, and the log-rank test was used to compare the estimated KM curves. Results: A total of 65,543 patients were included. The distribution by age, gender, and histology was the same for public and private systems. The majority of patients were diagnosed on stages I and II (77.8%) in the private system. However, in the public system, it was found more advanced stage disease (67.8% in stages II and III). Patients with metastatic tumor were more common in the public system (11.1% versus 5.3%). Treatment with surgery and, at least, two types of adjuvant therapy as trimodal therapy were the same in both groups (46.6% private versus 46.2% public). KM plot shows 5- and 10-years OS differences in all stages; 10-year OS in stages I, II, III, and IV in private and public systems were, respectively, 81.6 versus 77.5%, 74 versus 63.3%, 55.6% versus 39.6%, and 7.6 versus 6.4%. In the multivariable analyses, the significant independent predictors for OS were private system, age and stage at diagnosis, high-level education, and trimodal therapy. Conclusion: Older patients, less intensive treatment, and lower educational levels were independent predictors for worse OS. Public health system presented a more advanced stage at diagnosis than private care and was associated with worse survival outcomes in Brazilian breast cancer patients.
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Rammohan, Rajmohan, Melvin Joy, Sai Greeshma Magam, et al. "P252 Exploring the link between obesity and gastro-intestinal stromal tumor (GIST) readmission through Kaplan-Meier survival estimates." In BSG LIVE’24, 17-20 June 2024, ICC Birmingham. BMJ Publishing Group Ltd and British Society of Gastroenterology, 2024. http://dx.doi.org/10.1136/gutjnl-2024-bsg.334.
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"INTESTINAL FUNCTIONAL END-TO-END STAPLED ANASTOMOSIS WITH ENDOVASCULAR GASTROINTESTINAL ANASTOMOSIS STAPLERS IN SMALL DOGS AND CATS." In : London International Conference on Research in Life-Science & Healthcare, 19-20 June 2024. Global Research & Development Services, 2024. http://dx.doi.org/10.20319/icrlsh.2024.8485.
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Intestinal functional end-to-end stapled anastomoses (FEESA) are reported to have lower complication rates than hand-sewn anastomoses in dogs, however, the size of standard gastrointestinal anastomosis (GIA) staplers prevents their use in small patients due to the reduced intestinal diameter. Our study investigates the use of endovascular gastrointestinal (endo-GIA) staplers to perform functional end-to-end intestinal anastomosis in small dogs (≤ 10 kg) and cats. Methods: Retrospective study approved by the Royal College of Veterinary Surgeons Ethics Review Panel (approval number 2022-144). The medical record databases of five referral hospitals were searched for patients that underwent an intestinal FEESA using an endo-GIA stapler. Dogs with a body weight ≤10 kg and cats were included. Patients were excluded if the available follow-up was less than ten days post-surgery, unless a major complication developed. Outcomes of interest for each patient included diagnosis, intraoperative complications, postoperative complications and survival time. Estimated survival was generated according to the Kaplan-Meier method. Differences between survival curves were tested by log-rank test. Results: Twenty-five patients (10 dogs and 15 cats) were enrolled in the study. The mean body weight was 5.18 kg (range 2.6 – 10 kg). Nine patients were diagnosed with neoplasia, 16 with non-neoplastic disease. The median follow-up was 126 days (range 18-896 days). No major complications were recorded. Five patients developed minor postoperative complications that included 3 superficial surgical site infections. Eighteen patients were alive at the end of the study, one was lost at follow-up. Of the 6 patients who died, none were dead because of complications from the intestinal surgery. Kaplan-Meier estimated survival was not reached. Survival was significantly longer for patients with non-neoplastic versus neoplastic disease (P = 0.005). Conclusions: Our study suggests that the use of endo-GIA stapling devices is safe and effective to perform functional end-to-end intestinal anastomosis in small patients.
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Artun, E., and A. Al-Amri. "Time-To-Event Analysis of Shale Reservoir Performance: Identification of Key Drivers for CO2 Sequestration." In SPE Europe Energy Conference and Exhibition. SPE, 2025. https://doi.org/10.2118/225535-ms.
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Abstract Time-to-event analysis (i.e. survival analysis) is a well-established statistical approach to analyze the probability distribution of and impact of various parameters on a time-domain of interest. This approach has been mostly applied to various equipment failure prediction problems in the petroleum industry. This study aims to demonstrate this application by evaluating the dynamics of shale well performance, focusing on a case study of CO2 sequestration. We investigate the impact of reservoir and operational parameters on the time of injecting 1 Bscf of CO2 into the drainage area of a depleted shale gas well within an analysis duration of 40 years. The data set was compiled from a large number of numerical simulation scenarios, where each scenario mimics a specific CO2 sequestration scenario followed by primary production. The induced fractured network around the horizontal well was approximated via the stimulated reservoir volume (SRV) approach. Scenarios that took longer to reach the target injection volume were assumed to be censored from the analysis. Time-to-event analysis methods, including the Kaplan-Meier estimator, log-rank test and Cox proportional hazards model were applied to the data set of 2547 scenarios. The Kaplan-Meier curve reveals distinct CO2 injection phases resembling an inverse sigmoid shape, highlighting transitions between injection stages. The median time was ~19.5 years for 1 Bscf of injection, with most cases being completed between 10 and 25 years. Among the reservoir properties, initial pressure, temperature, thickness, Langmuir volume constant for CO2, fracture permeability and SRV permeability and porosity were found to be dominant as they altogether control storage, flow and adsorption capacities for CO2. Among the operational parameters, injection rate was the major factor, since the rate directly affects the time until a certain cumulative volume of injection is completed. Although the observations from the Cox proportional hazards model and the log-rank test were largely consistent, differences emerged due to the distinct assumptions and methodologies underlying each approach. When the injection rate was excluded from the Cox model, the significance of other reservoir and operational variables, such as SRV permeability, initial pressure, Langmuir volume constant, lateral length, production duration, and fracturing pressure, became more apparent. This study highlights the effectiveness of time-to-event analysis techniques in evaluating shale reservoir performance for CO2 injection scenarios. By integrating reservoir, geological, and operational factors, the findings provide a comprehensive understanding of sequestration dynamics.
Reports on the topic "Kaplan-Meier Estimate"
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Hollander, Myles, Frank Proschan, and James Sconing. Efficiency Loss with the Kaplan-Meier Estimator. Defense Technical Information Center, 1985. http://dx.doi.org/10.21236/ada161341.
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Lo, S. H., Y. P. Mack, and J. L. Wang. Hazard Rate Estimation for Censored Data via Strong Representation of the Kaplan-Meier Estimator. Defense Technical Information Center, 1985. http://dx.doi.org/10.21236/ada172031.
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