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      • Applying Conventional and Saturated Generalized Gamma Distributions in Parametric Survival Analysis of Breast Cancer

        Yavari, Parvin,Abadi, Alireza,Amanpour, Farzaneh,Bajdik, Chris Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.5

        Background: The generalized gamma distribution statistics constitute an extensive family that contains nearly all of the most commonly used distributions including the exponential, Weibull and log normal. A saturated version of the model allows covariates having effects through all the parameters of survival time distribution. Accelerated failure-time models assume that only one parameter of the distribution depends on the covariates. Methods: We fitted both the conventional GG model and the saturated form for each of its members including the Weibull and lognormal distribution; and compared them using likelihood ratios. To compare the selected parameter distribution with log logistic distribution which is a famous distribution in survival analysis that is not included in generalized gamma family, we used the Akaike information criterion (AIC; r=l(b)-2p). All models were fitted using data for 369 women age 50 years or more, diagnosed with stage IV breast cancer in BC during 1990-1999 and followed to 2010. Results: In both conventional and saturated parametric models, the lognormal was the best candidate among the GG family members; also, the lognormal fitted better than log-logistic distribution. By the conventional GG model, the variables "surgery", "radiotherapy", "hormone therapy", "erposneg" and interaction between "hormone therapy" and "erposneg" are significant. In the AFT model, we estimated the relative time for these variables. By the saturated GG model, similar significant variables are selected. Estimating the relative times in different percentiles of extended model illustrate the pattern in which the relative survival time change during the time. Conclusions: The advantage of using the generalized gamma distribution is that it facilitates estimating a model with improved fit over the standard Weibull or lognormal distributions. Alternatively, the generalized F family of distributions might be considered, of which the generalized gamma distribution is a member and also includes the commonly used log-logistic distribution.

      • KCI등재

        Effect of MAO-modified nanoporous silica supports with single-site titanocene catalyst on ethylene polymerization

        Farideh Azimfar,Alireza Badiei,Seyed Mehdi Ghafelebashi,Majid Daftari-Besheli,Abbas Rezaee Shirin-Abadi 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.4

        Three types of nanoporous silica support were modified by methylaluminoxane MAO and characterized by using BET, SEM, XRD and TGA. Dimethylsilyl (N-tert-butylamido)(tetramethylcyclopentadienyl) titanium dichlride was synthesized and immobilized on modified support. The prepared complex was then used as a reactive catalyst for ethylene polymerization. The effect of immobilization conditions on catalyst performance was studied. The results revealed elevated temperature grafting, decrease in precatalyst loading. Also, increasing of immobilization reaction time showed an increase in activity to 130 Kg poly/mol Ti.h.bar. The effects of polymerization temperature and [Al]/[Ti] ratio on the catalyst behavior, namely activity and bulk density, were investigated. According to the results, the activity of single-site catalyst depends on condition of immobilization and structure of nanoporous silica support.

      • Relative Survival of Breast Cancer Patients in Iran

        Kasaeian, Amir,Mosavi-Jarrahi, Alireza,Abadi, Alireza,Mahmoodi, Mahmood,Mehrabi, Yadollah,Mohammad, Kazem,Eshraghian, Mohammad Reza,Zare, Ali Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.14

        Background: The survival rate reflecting prognosis of breast cancer patients is usually estimated based on crude survival methods such as observed and cause-specific. In situations where data are based on population-cancer registries, this method may produce biased estimations. This study therefore aimed to estimate the net survival of breast cancer based on relative survival. Materials and Methods: Data for 622 breast cancer patients diagnosed at the Iran Cancer Institute during 1990-95 and tracked till the end of 2000 were analyzed. For estimation of relative survival, Ederer's second method and SAS (9.1) and STATA (11) software were used. Results: Threeyear relative survivals of 85%, 90%, 80% and 67% were observed for age groups 15-44, 55-59, 60-74, and 75+years-old, respectively. A relative survival of approximately one was observed for two subsequent years for age-group 45-59 years-old. A value greater than one for two subsequent years of follow-up was observed in the age-group 60-74 years-old. Conclusions: Tracking the diagnosis of breast cancer, the relative survival decreases as we go to higher age-groups. It is also perceived that through follow-up, relative survival first decreased and then increased a little. The statistical cure point is acceptable for age group 45-59 years-old while for age-groups 15-44 and 60-74 years old is a sign of low quality data for some follow-up intervals.

      • KCI등재

        Determinants of Adherence to Diabetes Screening in Iranian Adults With a Positive Family History of Diabetes

        Malih Narges,Sohrabi Mohammad-Reza,Abadi Alireza,Arshi Shahnam 대한예방의학회 2021 Journal of Preventive Medicine and Public Health Vol.54 No.3

        Objectives: Insufficient evidence exists regarding factors that affect screening adherence among people with a family history of diabetes, who comprise roughly half of all patients with diabetes. Therefore, we aimed to identify the determinants of diabetes screening adherence in adults with a family history of diabetes who had not yet been diagnosed with diabetes. Methods: This cross-sectional study was conducted at selected urban primary healthcare facilities in Tehran, Iran. The study population was clinically non-diabetic adults above 20 years of age with a family history of diabetes in at least 1 first-degree relative. All eligible people identified on randomly-selected days of the month were invited to join the study. Results: Among 408 participants, 128 (31.4%) had received a fasting blood glucose check during the last year. Using binary logistic regression, the independent predictors of screening adherence were knowledge of adverse effects of diabetes such as sexual disorders (odds ratio [OR], 3.05) and renal failure (OR, 2.73), the impact of family members’ advice on receiving diabetes screening (OR, 2.03), recommendation from a healthcare provider to have a fasting blood glucose check (OR, 2.61), and intention to have a fasting blood glucose check within the next 6 months (OR, 2.85). Other variables that predicted screening adherence were age (OR, 1.05), job (being a housekeeper; OR, 3.39), and having a college degree (OR, 3.55). Conclusions: Knowledge of the adverse effects of diabetes, physicians’ and healthcare providers’ advice about the benefits of early disease detection, and family members’ advice were independent predictors of screening adherence.

      • Associations of Demographic and Socioeconomic Factors with Stage at Diagnosis of Breast Cancer

        Mohaghegh, Pegah,Yavari, Parvin,Akbari, Mohammad Esmail,Abadi, Alireza,Ahmadi, Farzane Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.4

        Background: Stage at diagnosis is one of the most important prognostic factors of breast cancer survival. Because in the breast cancer case this may vary with socioeconomic characteristics, this study was performed to recognize the relationship between demographic and socioeconomic factors with stage at diagnosis in Iran. Materials and Methods: This cross-sectional, descriptive study conducted on 526 patients suffering from breast cancer and registered in Cancer Research Center of Shahid Beheshti University of Medical Sciences from 2008 to 2013. A reliable and valid questionnaire about family levels of socioeconomic status filled in by interviewing the patients via phone. For analyzing the data, Multinomial logistic regression, Kendal tau-b correlation coefficient and Contingency Coefficient tests were executed by SPSS22. Economic status, educational attainment of patient and household head and/or a combination of these were considered as parameters for socioeconomic status. First, the relationship between stage at diagnosis and demographic and socioeconomic status was assessed in univariate analysis then these relationships assessed in two different models of multinomial logistic regression. Results: The mean age of the patients was 48.3 (SD=11.4). According to the results of this study, there were significant relationships between stage at diagnosis of breast cancer with patient education (p=0.011), living place (p=0.044) and combined socioeconomic status (p=0.024). These relationships persisted in multiple multinomial logistic regressions. Other variables, however, had no significant correlation. Conclusions: Patient education, combined socioeconomic status and living place are important variables in stage at diagnosis of breast cancer in Iranian women. Interventions have to be applied with the aim of raising women's accessibility to diagnostic and medical facilities and also awareness in order to reducing delay in referring. In addition, covering breast cancer screening services by insurance is recommended.

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