Yazar "Ture, Mevlut" seçeneğine göre listele
Listeleniyor 1 - 18 / 18
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Airborne Fungal Concentrations in East Patch of Edirne City (Turkey) in Autumn Using Two Sampling Methods(Trakya Üniversitesi, 2005) Okten, Suzan Sarıca; Asan, Ahmet; Tungan, Yasemin; Ture, MevlutGece ve gündüz saatlerinde fungal konsantrasyonlar değişiklik gösterebilir. Kuru sporlar havaya gündüz salınırken nem oranı daha yüksek olan sporlar gece salınmaktadırlar. Türkiye’de havayla taşınan funguslar ile ilgili çalışmalar çok azdır ve yalnızca bazı şehirlerde günlük ve haftalık incelemeler yapılmıştır. Bu çalışmada Edirne şehri günlük fungal konsantrasyonlarının belirlenmesi amaçlanmıştır. Örnekler yerden 11 m yükseklikten alınmıştır. Örneklemeler 11 Ekim 2002 – 15 Kasım 2002 tarihleri arasında, hergün aynı saatlerde olmak üzere birer haftalık zaman dilimlerinde sabah 08.00 ve akşam 20.00’de yapılmıştır. Fungus izolasyonu için yerçekimine dayalı petri plak metodu ve volumetrik örnekleme metodu kullanılmıştır. Sıcaklık ve nısbi nem iklimsel faktörlerin fungal sporları etkileyip etkilemedikleri istatistiki olarak incelenmiş ve fungus sayıları, nısbi nem ve sıcaklık arasında korelasyon bulunmuştur. 42 petri plağına izole edilen toplam 800 fungus kolonisi bulunma sıklıkları belirlenerek cins düzeyinde tanımlamaları yapılmıştır. Volumetrik metot ile m3 de 9337 cfu mikrofungus belirlenmiştir. En baskınları Alternaria, Penicillium ve Trichoderma olan 7 fungus cinsi teşhis edilebilmiştir.Öğe Arginase and Ornithine in Human Benign and Malignant Skin Tumors(Walter De Gruyter Gmbh, 2010) Gokmen, Selma Suer; Kazezoglu, Cemal; Aygit, A. Cemal; Yildiz, Reyhan; Cakir, Beyhan; Ture, Mevlut; Gulen, SendoganObjectives: Arginase activity and ornithine concentration have been shown to be elevated in experimentally-induced benign tumors in mice. The aim of the study is to investigate arginase activity and ornithine concentration in human benign and malignant skin tumors and to evaluate their role for prognosis of skin tumors. Patients and Methods: We have investigated arginase activity and ornithine concentration in supernatant of homogenates of benign tumors (nevus) of the skin from 13 patients and of malignant tumors (squamous cell or basal cell carcinomas) from 29 patients. Total arginase activity, ornithine and total protein concentration in supernatant were determined by the methods of Geyer, Chinard and Lowry, respectively. Results: Arginase activity (p=0.006) and ornithine concentration (p=0.007) in nevus were significantly higher than in adjacent normal tissue. There was no significant difference between their levels in basal cell carcinoma and in nevus (p>0.05). There was no significant difference between ornithine concentration in squamous cell carcinoma and in nevus (p>0.05). However, arginase activity in this carcinoma was significantly higher than in nevus (p=0.018). Conclusion: The significant difference between tissue arginase activities in squamous cell carcinoma and in nevus indicates that determination of arginase activity could be useful for prognosis of skin tumors.Öğe Comparing performances of logistic regression, classification and regression tree, and neural networks for predicting coronary artery disease(Pergamon-Elsevier Science Ltd, 2008) Kurt, Imran; Ture, Mevlut; Kurum, A. TurhanIn this study, performances of classification techniques were compared in order to predict the presence of coronary artery disease (CAD). A retrospective analysis was performed in 1245 subjects (865 presence of CAT) and 380 absence of CAD). We compared performances of logistic regression (LR), classification and regression tree (CART), multi-layer perceptron (MLP), radial basis function (RBF), and self-organizing feature maps (SOFM). Predictor variables were age, sex, family history of CAD, smoking status, diabetes mellitus, systemic hypertension, hypercholesterolemia, and body mass index (BMI). Performances of classification techniques were compared using ROC curve, Hierarchical Cluster Analysis (HCA), and Multidimensional Scaling (MDS). Areas under the ROC curves are 0.783, 0.753, 0.745, 0.721, and 0.675, respectively for MLP, LR, CART, RBF, and SOFM. MLP was found the best technique to predict presence of CAD in this data set, given its good classificatory performance. MLP, CART, LR, and RBF performed better than SOFM in predicting CAD in according to HCA and MDS. (c) 2006 Elsevier Ltd. All rights reserved.Öğe Comparison of Bayesian survival analysis and Cox regression analysis in simulated and breast cancer data sets(Pergamon-Elsevier Science Ltd, 2009) Omurlu, Imran Kurt; Ozdamar, Kazim; Ture, MevlutWe aimed to compare the performance of Cox regression analysis (CRA) and Bayesian survival analysis (BSA) by using simulations and breast cancer data. Simulation study was carried out with two different algorithms that were informative and noninformative priors. Moreover, in a real data set application, breast cancer data set related to disease-free survival (DFS) that was obtained from 423 breast cancer patients diagnosed between 1998 and 2007 was used. In the simulation application, it was observed that BSA with noninformative priors and CRA methods showed similar performances in point of convergence to simulation parameter. In the informative priors' simulation application, BSA with proper informative prior showed a good performance with too little bias. It was found out that the bias of BSA increased while priors were becoming distant from reliability in all sample sizes. In addition, BSA obtained predictions with more little bias and standard error than the CRA in both small and big samples in the light of proper priors. In the breast cancer data set, age, tumor size, hormonal therapy, and axillary nodal status were found statistically significant prognostic factors for DFS in stepwise CRA and BSA with informative and noninformative priors. Furthermore, standard errors of predictions in BSA with informative priors were observed slightly. As a result, BSA showed better performance than CRA, when subjective data analysis was performed by considering expert opinions and historical knowledge about parameters. Consequently, BSA should be preferred in existence of reliable informative priors, in the contrast cases, CRA should be preferred. (C) 2009 Elsevier Ltd. All rights reserved.Öğe Comparison of dimension reduction methods using patient satisfaction data(Pergamon-Elsevier Science Ltd, 2007) Ture, Mevlut; Kurt, Imran; Akturk, ZekeriyaIn this study, we compared classical principal components analysis (PCA), generalized principal components analysis (GPCA), linear principal components analysis using neural networks (PCA-NN), and non-linear principal components analysis using neural networks (NLPCA-NN). Data were extracted from the patient satisfaction query with regard to the satisfaction of patients from hospital staff, which was applied in 2005 at the outpatient clinics of Trakya University Medical Faculty. We found that percentages of explained variance of principal components from PCA-NN and NLPCA-NN were highest for doctor, nurse, radiology technician, laboratory technician, and other staff using a patient satisfaction data set. Results show that methods using NN which have higher percentages of explained variances than classical methods could be used for dimension reduction. (C) 2005 Elsevier Ltd. All rights reserved.Öğe The comparisons of prognostic indexes using data mining techniques and Cox regression analysis in the breast cancer data(Pergamon-Elsevier Science Ltd, 2009) Ture, Mevlut; Tokatli, Fusun; Omurlu, Imran KurtThe purpose of this study is to determine new prognostic indexes for the differentiation of subgroups of breast cancer patients with the techniques of decision tree algorithms (C&RT, CHAID, QUEST, ID3, C4.5 and C5.0) and Cox regression analysis for disease-free survival (DFS) in breast cancer patients. A retrospective analysis was performed in 381 breast cancer patients diagnosed. Age, menopausal status, age of menarche, family history of cancer, histologic tumor type, quadrant of tumor, tumor size, estrogen and progesterone receptor status, histologic and nuclear grading, axillary nodal status, pericapsular involvement of lymph nodes, lymphovascular and perineural invasion, adjuvant radiotherapy, chemotherapy and hormonal therapy were assessed. Based on these prognostic factors, new prognostic indexes for C&RT, CHAID, QUEST, ID3, C4.5 and C5.0 and Cox regression were obtained. Prognostic indexes showed a good degree of classification, which demonstrates that an improvement seems possible using standard risk factors. We obtained that C4.5 has a better performance than C&RT, CHAID, QUEST, ID3, C5.0 and Cox regression to determine risk groups using Random Survival Forests (RSF). (C) 2008 Elsevier Ltd. All rights reserved.Öğe The comparisons of random survival forests and Cox regression analysis with simulation and an application related to breast cancer(Pergamon-Elsevier Science Ltd, 2009) Omurlu, Imran Kurt; Ture, Mevlut; Tokatli, FuesunThe objective of this study was to compare the performances of Cox regression analysis (CRA) and random survival forests (RSF) methods with simulation and a real data set related to breast cancer. In the simulations, we compared across the methods under varying sample sizes by using Monte Carlo simulation method. The results showed that the performance of the CRA was a slightly better for analysis based on Harrell's concordance index than RSF approaches based on log-rank, conservation of events, log-rank score and approximate log-rank splitting rules. In the real data application, a retrospective analysis was performed in 279 breast cancer patients diagnosed. According to Harrell's concordance index, RSF based on approximate log-rank splitting rule to determined major risk factors for disease-free survival (DFS) showed a slightly better performance than other approaches. In general, performances of all the methods were almost similar. The predictive capability of CRA can be used for different sample sizes and potential future suitable survival data problems, whereas RSF provide interpretive results. (C) 2008 Elsevier Ltd. All rights reserved.Öğe Developing and comparing two different prognostic indexes for predicting disease-free survival of nonmetastatic breast cancer patients(Tubitak Scientific & Technological Research Council Turkey, 2011) Tokatli, Zehra Fusun; Ture, Mevlut; Omurlu, Imran Kurt; Alas, Rusen Cosar; Uzal, Mustafa CemAim: To determine 2 different prognostic indexes (PI) for the differentiation of subgroups of nonmetastatic breast cancer patients with the Cox regression analysis and survival tree (ST) methods and the additional usage of the Kaplan-Meier estimates to investigate the predictive power of these methods. Materials and methods: Prognostic factors data were collected for 410 patients. The Cox regression analysis examines the relationship of the survival distribution and covariates. The ST method is a tree-structured survival analysis based on a recursive partitioning algorithm. In this study, Harrell's concordance indexes of models for training and test sets were computed. Furthermore, survival curves were estimated by the Kaplan-Meier method. Disease-free survival (DFS) was calculated from the time of initial diagnosis (initiation of the first treatment) to the first recurrence of disease. Results: After a median follow-up of 48 months, 100 (24.4%) patients have had at least 1 of the DFS events. In Cox regression analysis, we proposed the simple PI, which is a sum of axillary nodal and HER2/neu status. In the ST method, we identified 3 variables: HER2/neu, axillary nodal, and estrogen receptor status. The axillary nodal status was the most important determining factor for recurrence. Conclusion: We found that the PI of the ST and Cox regression methods had similar performance levels in predicting DFS, and the error rates of the models were close to each other in the training and test sets. Furthermore, we determined that the axillary nodal status and HER2/neu were the most important determining factors for prediction of DFS in breast cancer patients.Öğe Do dietary calcium intake and hormone replacement therapy affect bone mineral density in women?(Aves Yayincilik, Ibrahim Kara, 2008) Ozdemir, Ferda; Kabayel, Derya Demirbag; Ture, MevlutObjectives: In this study, the relationship between postmenopausal bone mineral density (BMD), and hormone replacement therapy (HRT) and the level of dietary calcium intake in women was investigated. Patients and Methods: Two hundred postmenopausal women (mean age 58.89 +/- 8.51 years; range 42 to 83 years) were evaluated retrospectively. Menopausal age and duration, HRT status, and daily dietary calcium intake of all patients were recorded. Evaluation of BMD was made with Dual Energy X-Ray Absorptiometry (DEXA) from lumbar spine and femur and the T scores were obtained. Results: There was a significant negative correlation between the patients' age and duration of menopause, and BMD. The BMD values of the patients not receiving HRT were significantly lower than those of the patients receiving HRT In women with dietary calcium intake above 1000 mg/day, spine and femur BMD values were significantly higher than in those with an intake below 600 mg/ day and between 600-1000 mg/day. Conclusion: We think that dietary calcium intake and HRT status can be an indicator for BMD in postmenopausal women.Öğe The Effect of Cisplatin plus Etoposide Therapy on Serum Total and Lipid-Bound Sialic Acid Levels in Patients with Non-small Cell Lung Cancer(Turkish Biochem Soc, 2010) Gokmen, Selma Suer; Kazezoglu, Cemal; Tabakoglu, Erhan; Gungor, Ozgul; Altiay, Gundeniz; Ture, MevlutObjectives: To investigate the effect of cisplatin+etoposide therapy on serum total and lipid-bound sialic acid levels in patients with non-small cell lung cancer and evaluate the role of these parameters in the monitoring of the therapy. Patients and Methods: To 18 patients (all men) who are newly diagnosed as nonsmall cell lung cancer, cisplatin was given intravenously (80mg/m(2)) on day 1 and etoposide was given (100mg/m(2)) on day 1-3 to the patients once at an interval of 21 day. Blood samples before the first chemotherapy were compared with those obtained after the second and third chemotherapy. The percent of chemotherapy responses of patients were also calculated. Total and lipid-bound sialic levels were determined by the methods of Warren and Katopodis, respectively. Results: There was a significant decrease in serum lipid-bound sialic acid levels after the second chemotherapy when compared with those before the first chemotherapy (t=2.216, p=0.041). Positive response to cisplatin+etoposide therapy was observed in 88.89% (11.11% of total response, 44.44% of partial response and 33.33% of stable response) of the patients. Progressive disease was established in only 11.11% of the patients. It was found a statistically significant decrease in both serum total (t=2.924, p=0.017) and lipid-bound sialic acid (t=3.635, p=0.005) levels after the third chemotherapy when compared with those before the first chemotherapy. Conclusion: Determination of serum total and lipid-bound sialic acid levels besides routine applications may be useful in the monitoring of cisplatin+etoposide therapy.Öğe High C-reactive protein and low cholesterol levels are prognostic markers of survival in severe sepsis(Elsevier Science Inc, 2007) Memis, Dilek; Gursoy, Olcay; Tasdogan, Muhittin; Sut, Necdet; Kurt, Imran; Ture, Mevlut; Karamanlioglu, BeyhanStudy Objective: To evaluate serum C-reactive protein and cholesterol as a prognostic factor for Survival in patients with severe sepsis. Design: Prospective study. Setting: University hospital. Patients: The study population consisted of 96 patients (age range, 18-75 years; median, 56 years; men/women ratio, 40:56) in whom severe sepsis was diagnosed. Interventions: Patients' serum levels of C-reactive protein and cholesterol were measured upon admission to an intensive care unit, two days later, and on the day of discharge from the intensive care unit or on the day of death. Measurements and Main Results: Cholesterol levels were significantly lower among the nonsurviving patients (day 1, 92.2 +/- 25.1 mg/dL; day 2, 92.1 +/- 21.7 mg/dL; death/discharge day, 92.2 +/- 21.7 mg/dL) than surviving patients (day 1, 175.1 +/- 38.6 mg/dL [P < 0.001]; day 2, 173.0 +/- 39.3 mg/dL [P < 0.001]; death/discharge day, 171.8 +/- 39.6 mg/dL [P = 0.010]). Median C-reactive protein levels were significantly higher among the nonsurvivors (day 1, 32 mg/dL [range, 20.5-64.5 rng/dL]; day 2, 33 mg/dL [range, 22-74.5 mg/dL]; death/discharge day, 30 rng/dL [range, 22-57 mg/dL]) than survivors (day 1, 10 rng/dL [range, 6-14 mg/dL]; day 2, 9 mg/dL [range, 5-10 mg/dL]; death/discharge day, 6 mg/dL [range, 3-9 mg/dL]; P < 0.001). Conclusion: Serum C-reactive protein and cholesterol are a predictor of survival in patients with severe sepsis. Low cholesterol and high C-reactive protein levels appear as a valuable tool for individual risk assessment in severe sepsis patients and for stratification of high-risk patients in future intervention trials. (C) 2007 Elsevier Inc. All rights reserved.Öğe The importance of serum total and lipid-bound sialic acid as markers in patients with small cell and non-small cell lung carcinoma(Aves Yayincilik, Ibrahim Kara, 2007) Gokmen, Selma Suer; Kazezoglu, Cemal; Tabakoglu, Erhan; Altiay, Guendeniz; Gungoer, Ozgul; Ture, MevlutObjectives: Serum total sialic acid (TSA) and lipid-bound sialic acid (LSA) levels were investigated in patients with small and non-small cell lung carcinoma and their role in discriminating small from non-small cell lung carcinoma and lung carcinoma from healthy individuals was evaluated. Patients and Methods: The study included 159 male patients with non-small cell lung carcinoma (n=102) and small cell lung carcinoma (n=57) who never received chemotherapy and/or radiotherapy and 35 healthy volunteers as controls. Serum TSA and LSA levels were determined by the methods of Warren and Katopodis, respectively. Results: Serum TSA and LSA levels in both patient groups were significantly elevated when compared with controls (p < 0.001), but the patient groups did not differ significantly in this respect. Receiver operating characteristic (ROC) analysis showed that TSA was more specific and LSA was more sensitive in distinguishing patients with non-small cell carcinoma from healthy individuals. On the other hand, LSA was found to be more sensitive in distinguishing patients with small cell carcinoma from healthy controls. Conclusion: Serum total and lipid-bound sialic acid may play an important role as biochemical markers in distinguishing patients with small and non-small cell lung carcinoma from healthy subjects.Öğe L-Carnitine Ameliorates Glycerol-Induced Myoglobinuric Acute Renal Failure in Rats(Taylor & Francis Ltd, 2009) Ustundag, Sedat; Sen, Saniye; Yalcin, Omer; Ciftci, Senturk; Demirkan, Bora; Ture, MevlutThere is increasing evidence indicating that oxidative stress plays an important role in the pathogenesis of rhabdomyolysis-induced myoglobinuric acute renal failure (ARF). During times of war and natural disasters, myoglobinuric ARF can assume epidemic proportions. Thus, early and effective renoprotective treatments are of utmost importance. It has been shown that L-carnitine, used as a safe and effective nutritional supplement for more than three decades, is effective in preventing renal injury in many renal injury models involving oxidative stress. The present study was performed to investigate the effects of L-carnitine in an experimental model of myoglobinuric ARF. Four groups of rats were employed in this study: group 1 served as a control; group 2 was given glycerol (10 mL/kg, i.m.); group 3 was given glycerol plus L-carnitine (100 mg/kg, i.p.), starting at the same time as the glycerol injection; group 4 was given glycerol plus L-carnitine (100 mg/kg, i.p.), starting 48h before the glycerol injection. After glycerol injections, the i.p. injections of L-carnitine were repeated every 24h for four days. Ninety-six hours after glycerol injections, blood samples and kidney tissues were taken from the anesthetized rats. Urea and creatinine levels in plasma, N-acetyl-beta-D-glucosaminidase activity in urine, and malondialdehyde levels and catalase enzyme activity in kidney tissue were determined. Histopathological changes and iron accumulation in the kidney tissue were evaluated. In this study, glycerol administration led to marked renal oxidative stress, as well as severe functional and morphological renal deterioration. L-carnitine, possibly via its antioxidant properties, ameliorates glycerol-induced myoglobinuric kidney injury.Öğe Prevalence of asthma among preschool children in Edirne, Turkey(Allergy Immunol Soc Thailand, 2007) Yolsal, Guner Emel; Yazicioglu, Mehtap; Ture, Mevlut; Kurt, ImranAllergic diseases generally begin early during childhood, but a late diagnosis is common. This study aimed to evaluate the prevalence of asthma and asthma-related symptoms among kindergarten children in Edirne, Turkey. 873 subjects based on a modified ISAAC questionnaire were included. The prevalence of 'wheezing ever' and 'wheezing during the previous year' was 23.3% and 8.6%, respectively. Prior physician diagnoses existed for 36 of 873 (4.1%) children. The prevalence of children undiagnosed with asthma, but reporting asthma-related symptoms was 3.1%, 51.9% of which had previous beta-agonist prescriptions. However, none of these children received inhaled anti-inflammatory medications. In conclusion, it was found that a large population of preschool children had undiagnosed respiratory symptoms suggestive of asthma. Conducting simple surveys of young children is particularly important, as identification of asthma early in the disease course will facilitate effective prevention and treatment.Öğe Prognostic value DCE-MRI parameters in predicting factor disease free survival and overall survival for breast cancer patients(Elsevier Ireland Ltd, 2012) Tuncbilek, Nermin; Tokatli, Fusun; Altaner, Semsi; Sezer, Atakan; Ture, Mevlut; Omurlu, Imran Kurt; Temizoz, OsmanPurpose: The aim of the study is to assess the predictive power of DCE-MRI semi-quantitative parameters during treatment of breast cancer, for disease-free (DFS) and overall survival (OS). Materials and methods: Forty-nine women (age range, 28-84 years; mean, 50.6 years) with breast cancer underwent dynamic contrast enhancement MRI at 1.0 T imaging, using 2D FLASH sequences. Time intensity curves (TICs) were obtained from the regions showing maximal enhancement in subtraction images. Semi-quantitative parameters (TICs; maximal relative enhancement within the first minute, E (max/1); maximal relative enhancement of the entire study, E-max; steepest slope of the contrast enhancement curve; and time to peak enhancement) derived from the DCE-MRI data. These parameters were then compared with presence of recurrence or metastasis, DFS and OS by using Cox regression (proportional hazards model) analysis, linear discriminant analysis. Results: The results from of the 49 patients enrolled into the survival analysis demonstrated that traditional prognostic parameters (tumor size and nodal metastasis) and semi-quantitative parameters (E-max/1, and steepest slope) demonstrated significant differences in survival intervals (p < 0.05). Further Cox regression (proportional hazards model) survival analysis revealed that semi-quantitative parameters contributed the greatest prediction of both DFS, OS in the resulting models (for E-max/1: p = 0.013, hazard ratio 1.022; for stepest slope: p = 0.004, hazard ratio 1.584). Conclusion: This study shows that DCE-MRI has utility predicting survival analysis with breast cancer patients. (C) 2011 Elsevier Ireland Ltd. All rights reserved.Öğe Protective effects of L-carnitine and alpha-lipoic acid in rats with adjuvant arthritis(Academic Press Ltd- Elsevier Science Ltd, 2007) Tastekin, Nurettin; Aydogdu, Nurettin; Dokmeci, Dikmen; Usta, Ufuk; Birtane, Murat; Erbas, Hakain; Ture, MevlutFree radicals play an important role in the pathophysiology of adjuvant arthritis. The purpose of this study was to assess the efficacy Of L-carnitine (LC) and alpha-lipoic acid (alpha-LA) which are known to have antioxidant effects, in the treatment of adjuvant arthritis. Arthritis model was created by the administration of complete Freund's adjuvant (CFA) in 32 of 40 male Sprague-Dawley rats. The rats were divided into five groups. Rats in Group I served as controls and received 0.1 ml kg(-1) saline. Group II received only 0.1 ml of CFA and served as the CFA-control for the other groups. Groups III-V, after being injected with CFA, were treated with LC, alpha-LA or diclofenac, respectively. Levels of malondialdehyde (MDA) and glutathione (GSH) were measured in plasma samples. Enzyme activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx) were measured. The paws of rats were evaluated histopathologically to investigate the anti-inflammatory effects. TNF-alpha levels were measured for the evaluation of inflammation. In G roup II plasma MDA increased, levels of glutathione decreased, enzymeactivities of SOD and GPx decreased. Histopathological damage increased in the paws of the rats in this group. MDA levels decreased in Groups III-V when compared with Group II. GSH levels significantly increased in Group III and IV than Group V. SOD activity of Group IV was higher than Group III and V. TNF-alpha levels were significantly lower in Group IV and V. LC and a-LA seemed to have protective effects against oxidative damage in adjuvant arthritis model. (c) 2007 Elsevier Ltd. All rights reserved.Öğe The use of cyclic processes in medical decision making(Aves Yayincilik, Ibrahim Kara, 2007) Sut, Necdet; Ture, Mevlut; Senocak, MustafaObjectives: We aimed to explain the conceptual basis of the Markov model and to show the use of this model by an example application in medical decision making and medical predicting. Study Design: An example model regarding the effectiveness of St. Jude Total Therapy XIIIB protocol in Acute Lymphoblastic Leukemia (ALL) was hypothesised to evaluate the Markov model concept. The expected remission probabilities in 10 cycles were calculated in a cohort simulation with 10,000 trials, in a cohort in remission in the initial state. Results: Markov models are effective prediction models when the timing of events is important, when the decision problem involves risk over time and when events. may happen more than once (as in recurrence). Markov models can be used in estimating such events. As a result of derived model, the remission probability without relaps of any case treatrd with St. Jude Total Therapy XIIIB protocol in ALL disease in the second cycle was found as 43% and it was sharply reduced after this cycle. Conclusion: Cost, effectiveness, and health-related quality of life criteria of clinical strategies can be synthesised by the help of Markov models and used in the calculation of life expectancy, quality adjusted life expectancy and lifetime cost.Öğe Using Kaplan-Meier analysis together with decision tree methods (C&RT, CHAID, QUEST, C4.5 and ID3) in determining recurrence-free survival of breast cancer patients(Pergamon-Elsevier Science Ltd, 2009) Ture, Mevlut; Tokatli, Fusun; Kurt, ImranCurrent evidence supports a clear association between clinical and pathologic factors and recurrence-free survival (RFS) in breast cancer patients. The Cox regression model is the most common tool for investigating simultaneously the influence of several factors oil the survival time of patients. But it gives no estimate of the degree of separation of the different Subgroups. We propose to analyze different decision tree methods (C&RT, CHAID. QUEST, C4.5 and ID3) and use them additionally to the well-known Kaplan-Meier estimates to investigate the predictive power of these methods. Five hundred patients were included to the study. Two hundred and seventy-nine of them had complete data for prognostic factors and median follow-up is about 40.5 months. First, decision tree methods were analyzed for prognostic factors. Then, according to multidimensional scaling method C4.5 (error rate 0.2258 for training set and 0.3259 for cross-validation) performed slightly better than other methods in predicting risk factors for recurrence. Tumor size, age of menarche, hormonal therapy. histological grade and axillary nodal Status arc found that in important risk factors for the recurrence. Eight terminal nodes were found and stratified by Kaplan-Meier survival curves. Larger tumor size (>= 4.4 cm) and receiving no hormonal therapy in a small subgroup of patients were associated with worse prognosis. The five-year RFS is 71.3% in the whole patient population. The sensitivity, specificity and predictive rates calculated by C4.5 method were found 43.8%, 91% and 77.4% respectively. In this study, C4.5 showed a better degree of separation. As a result, we recommend 10 use decision tree methods together with Kaplan-Meier analysis to determine risk factors and effect of this factors oil survival. (C) 2008 Elsevier Ltd. All rights reserved.
