7 resultados para Regressão de Cox

em Universidade Federal do Rio Grande do Norte(UFRN)


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The aging process if characterizes for a complex events network, from multidimensional nature, that encloses biological, social, psychic and functional aspects. The alteration of one or more aspects can speed up the aging process, anticipating limitations and until the death in the aged. For an adjusted confrontation of this question is necessary an interdisciplinary vision, in which the some areas of the knowledge can interact and with this to intervenes of the best possible form. Then, information derived from studies of aspects related to incidence, morbidity-mortality and transition patterns, involved in the health-illness process can more accurately identify risk groups thereby establishing links between social factors, illness, incapacity and death. Thus, this study aimed to identify, by a multidimensional vision, the risk factors of mortality in a coorth of elderly in a city in the interior of the state of Rio Grande do Norte (RN), Brazil. A prospective study carried out in Santa Cruz RN, where 310 elderly were randomly selected to form a baseline. The follow-up was 53 months. The predictive variables were divided into sociodemographic, physical health, neuropsychiatric and functional capacity. The statistical analysis carried out by bivariate analysis, survival analysis, followed by binary logistic regression and Cox regression, in the multivariate analysis, considering significant levels p < 0.05 and confidence interval (CI) of 95%. A total of 60 (19.3%) elderly died during the follow-up, where cardiovascular disease was the main cause. The survival was approximately 24.8 months. The study of general survival showed, at 12, 24, 36, and 48 months of observation, a survival rate of 97%, 54%, 31%, and 5% respectively, with a statistical difference in survival only observed for the variables of cognitive function and Basic Activities of Daily Living. In the logistic regression analysis, the risk factors identified were cognitive deficits (OR = 8.74), poor perception of health (OR = 3.89) and dependence for Basic Activities of Daily Living (OR = 3.96). In the Cox analysis, as well as dependence for Basic Activities of Daily Living (HR = 3.17), cognitive deficit (HR = 4.30) and stroke (CVA) (HR = 3.49) continued as independent risk factors for death. The risk factors found in the study can be interpreted as the primary predictors for death among elderly members of the community. Therefore, improvements in health conditions, with actions towards sustaining an autonomous life with special attention for elderly with cognitive impairment, could mean additional healthy quality of life, resulting in the reduction of premature mortality in this population

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Introduction: Mouth cancer is classified as having one of the ten highest cancer incidences in the world. In Brazil, the incidence and mortality rates of oral cancer are among the highest in the world. Intraoral cancer (tongue, gum, floor of the mouth, and other non-specified parts of the mouth), the accumulated survival rate after five years is less than 50%. Objectives: Estimate the accumulated survival probability after five years and adjust the Cox regression model for mouth and oropharyngeal cancers, according to age range, sex, morphology, and location, for the city of Natal. Describe the mortality and incidence coefficients of oral and oropharyngeal cancer and their tendencies in the city of Natal, between 1980 and 2001 and between 1997 and 2001, respectively. Methods: Survival data of patients registered between 1997 and 2001 was obtained from the Population-based Cancer Record of Natal. Differences between the survival curves were tested using the log-rank test. The Cox proportional risk model was used to estimate risk ratios. The simple linear regression model was used for tendency analyses of the mortality and incidence coefficients. Results: The probability after five years was 22.9%. The patients with undifferentiated malignant neoplasia were 4.7 times more at risk of dying than those with epidermoid carcinoma, whereas the patients with oropharyngeal cancer had 2.0 times more at risk of dying than those with mouth cancer. The mouth cancer mortality and incidence coefficients for Natal were 4.3 and 2.9 per 100 000 inhabitants, respectively. The oropharyngeal cancer mortality and incidence coefficients were, respectively, 1.1 and 0.7 per 100 000 87 inhabitants. Conclusions: A low survival rate after five years was identified. Patients with oropharyngeal cancer had a greater risk of dying, independent of the factors considered in this study. Also independent of other factors, undifferentiated malignant neoplasia posed a greater risk of death. The magnitudes of the incidence coefficients found are not considered elevated, whereas the magnitudes of the mortality coefficients are high

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Telecommunication is one of the most dynamic and strategic areas in the world. Many technological innovations has modified the way information is exchanged. Information and knowledge are now shared in networks. Broadband Internet is the new way of sharing contents and information. This dissertation deals with performance indicators related to maintenance services of telecommunications networks and uses models of multivariate regression to estimate churn, which is the loss of customers to other companies. In a competitive environment, telecommunications companies have devised strategies to minimize the loss of customers. Loosing customers presents a higher cost than obtaining new ones. Corporations have plenty of data stored in a diversity of databases. Usually the data are not explored properly. This work uses the Knowledge Discovery in Databases (KDD) to establish rules and new models to explain how churn, as a dependent variable, are related to a diversity of service indicators, such as time to deploy the service (in hours), time to repair (in hours), and so on. Extraction of meaningful knowledge is, in many cases, a challenge. Models were tested and statistically analyzed. The work also shows results that allows the analysis and identification of which quality services indicators influence the churn. Actions are also proposed to solve, at least in part, this problem

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The aim of this study was determine whether an association exists in the gum tissue between the expression of markers of tissue hypoxia (HIF-1α and GLUT-1) with a marker of inflammatory activity (COX-2) and a marker of collagen degradation (EMMPRIN). Was performed immunohistochemistry with antibodies specific for these markers on 60 samples of gingival tissue divided into two groups: gums (n = 26) and gingivitis (n = 34) and expression was analyzed in the epithelial tissue and connective tissue . The reactivity epithelial for COX-2 was observed in only two cases as the HIF-1α, GLUT-1 and EMMPRIN was strongly expressed in the epithelial basal layer and the immunostaining was gradually decreased as the cells away from this layer, and negative in the region suprabasal in most specimens. In connective tissue, and HIF-1α EMMPRIN were strongly positive for most cases analyzed as GLUT-1 was negative in most cases. Immunostaining for COX-2 showed an association with gingival inflammatory infiltrate. The expression of EMMPRIN, HIF-1α and GLUT-1 in normal gums confirms the physiological role of these markers, however there was no association with tissue inflammation. Given the findings we can conclude that the inflammatory changes installed in frames of chronic gingivitis may not be sufficient to activate the factors of hypoxia to levels that can be quantified by immunohistochemical analysis, in addition, the findings are not conclusive in relationship to involvement of EMMPRIN in the secretion of MMPs to degrade collagen in the frames of gingivitis. We suggest the use of technical analysis and quantification of RNA of EMMPRIN and MMPs in order to determine whether collagen degradation observed in gingivitis suffers or not, significant influence of EMMPRIN for secretion and activation of MMPs

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The main goal of Regression Test (RT) is to reuse the test suite of the latest version of a software in its current version, in order to maximize the value of the tests already developed and ensure that old features continue working after the new changes. Even with reuse, it is common that not all tests need to be executed again. Because of that, it is encouraged to use Regression Tests Selection (RTS) techniques, which aims to select from all tests, only those that reveal faults, this reduces costs and makes this an interesting practice for the testing teams. Several recent research works evaluate the quality of the selections performed by RTS techniques, identifying which one presents the best results, measured by metrics such as inclusion and precision. The RTS techniques should seek in the System Under Test (SUT) for tests that reveal faults. However, because this is a problem without a viable solution, they alternatively seek for tests that reveal changes, where faults may occur. Nevertheless, these changes may modify the execution flow of the algorithm itself, leading some tests no longer exercise the same stretch. In this context, this dissertation investigates whether changes performed in a SUT would affect the quality of the selection of tests performed by an RTS, if so, which features the changes present which cause errors, leading the RTS to include or exclude tests wrongly. For this purpose, a tool was developed using the Java language to automate the measurement of inclusion and precision averages achieved by a regression test selection technique for a particular feature of change. In order to validate this tool, an empirical study was conducted to evaluate the RTS technique Pythia, based on textual differencing, on a large web information system, analyzing the feature of types of tasks performed to evolve the SUT

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Base excision repair (BER) and nucleotide excision repair (NER) pathways play critical role in maintaining genome integrity. Polymorphisms in BER and NER genes which modulate the DNA repair capacity may affect the susceptibility and prognosis of oral cancer. This study was conducted with genomic DNA from 92 patients with oral squamous cell carcinomas (OSCC) and 130 controls. The cases were followed up to explore the associations between BER and NER genes polymorphisms and the risk and prognosis of OSCC. Four single-nucleotide polymorphisms (SNPs) in XRCC1 (rs25487), APEX1 (rs1130409), XPD (rs13181) and XPF (rs1799797) genes were tested by polymerase chain reaction – quantitative real time method. The GraphPad Prism version 6.0.1 statistical software was applied for statistical analysis of association. Odds ratio (OR), hazard ratio (HR), and their 95 % confidence intervals (CIs) were calculated by logistic regression. Kaplan-Meier curve and Cox proportional hazard model were used for prognostic analysis. The presence of polymorphic variants in XRCC1, APEX1, XPD and XPF genes were not associated with an increased risk of OSCC. Gene-environment interactions with smoking were not significant for any polymorphism. The presence of polymorphic variants of the XPD gene in association with alcohol consumption conferred an increased risk of 1.86 (95% CI: 0.86 – 4.01, p=0.03) for OSCC. Only APEX1 was associated with decreased specific survival (HR 3.94, 95% CI: 1.31 – 11.88, p=0.01). These results suggest an interaction between polymorphic variants of the XPF gene and alcohol consumption. Additionally APEX1 may represent a prognostic marker for OSCC.

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Actinic cheilitis (AC) is a potentially malignant disorder which affects the lip vermilion and results from chronic exposure to sunlight. Currently, it is not possible to predict which cases of AC may progress to squamous cell carcinoma, and therefore, some biomolecular markers have been researched. Cyclooxygenase 2 (COX-2) is an enzyme associated with inflammatory response which is overexpressed in oral cancer; however, little is known about the role of this protein in actinic cheilitis. About the treatment of this lesion, currently available therapeutic modalities to AC may cause cytotoxic effects and deleterious results to patients. Therefore, the aim of this study was to evaluate the immunoexpression of COX-2 in AC of different risks of malignant transformation and analyse, through clinical follow-up, the efficacy of diclofenac sodium 3% gel in the treatment of this condition. Epithelial immunoexpression of COX-2 was analysed semi-quantitatively in 90 cases of AC classified as low risk (n = 55) and high risk (n = 35) of malignant transformation, in which the scores were assigned: (0) 0 to 5% of positive cells - Negative; (1) 6 to 30% of positive cells - Low expression; (2) 31 to 100% of positive cells - High expression. The chi-square test of Pearson was conducted to verify possible associations between immunoexpression of COX-2 and histologic grade of actinic cheilitis. The weighted kappa coefficient denoted a good interobserver agreement (0.677). Nineteen patients diagnosed with AC were instructed to perform topical application of the gel three times a day for a period of 90 days. In each biweekly visit, a follow-up record was accomplished through digital photographs and after treatment was completed, two researchers analysed all the images to assess clinical aspects of the lip. Furthermore, tolerability to the drug and patient satisfaction after treatment were evaluated. COX-2 was overexpressed in 74.4% of AC cases. Both low and high-risk groups revealed predominance of score 3, followed by scores 2 and 1. There was no significant association (p = 0.315) between COX-2 expression and histological grading. Among the total number of participants of this clinical study, ten showed total remission of all clinical features of the lesion and three had partial improvement of these characteristics. One participant presented worsening of the clinical condition. In five cases, the treatment was discontinued due to development of mild adverse effects at the site of gel application. Regarding analysis of satisfaction and tolerability to the drug, most patients were fully satisfied with the therapy (n = 11) and reported that the drug was not irritating to the lips (n = 9). Our study demonstrates that high expression of COX-2 is common in AC; however, this protein was not associated with malignant transformation risk of the analysed cases. Topical application of diclofenac sodium 3% gel provided a convenient and well tolerated approach in most cases, and may be a promising alternative for the treatment of actinic cheilitis.