• 대한예방의학회:학술대회논문집
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• 2003.04a
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• pp.30-37
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• 2003

o Cohort study became the major approach to study of chronic diseases such as CVD and cancer o Cohort can be population-based or volunteer-based o Types of be population-be categorized by source population and selection mechanism o More and more cohort studies involve biological specimens, such as blood, urine, toenail, cheek cells, etc. o Multi-center and multi-national collaboration is an effective way to increase sample size. o Current statistical method typically use time-to-event analysis by Cox proportional hazard model.

• Korean Journal of Radiology
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• v.23 no.9
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• pp.921-930
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• 2022

Objective: To identify epidermal growth factor receptor (EGFR) mutations in lung adenocarcinoma based on ¹⁸F-fluorodeoxyglucose (FDG) PET/CT radiomics and clinical features and to distinguish EGFR exon 19 deletion (19 del) and exon 21 L858R missense (21 L858R) mutations using FDG PET/CT radiomics. Materials and Methods: We retrospectively analyzed 179 patients with lung adenocarcinoma. They were randomly assigned to training (n = 125) and testing (n = 54) cohorts in a 7:3 ratio. A total of 2632 radiomics features were extracted from the tumor region of interest from the PET (1316) and CT (1316) images. Six PET/CT radiomics features that remained after the feature selection step were used to calculate the radiomics model score (rad-score). Subsequently, a combined clinical and radiomics model was constructed based on sex, smoking history, tumor diameter, and rad-score. The performance of the combined model in identifying EGFR mutations was assessed using a receiver operating characteristic (ROC) curve. Furthermore, in a subsample of 99 patients, a PET/CT radiomics model for distinguishing 19 del and 21 L858R EGFR mutational subtypes was established, and its performance was evaluated. Results: The area under the ROC curve (AUROC) and accuracy of the combined clinical and PET/CT radiomics models were 0.882 and 81.6%, respectively, in the training cohort and 0.837 and 74.1%, respectively, in the testing cohort. The AUROC and accuracy of the radiomics model for distinguishing between 19 del and 21 L858R EGFR mutational subtypes were 0.708 and 66.7%, respectively, in the training cohort and 0.652 and 56.7%, respectively, in the testing cohort. Conclusion: The combined clinical and PET/CT radiomics model could identify the EGFR mutational status in lung adenocarcinoma with moderate accuracy. However, distinguishing between EGFR 19 del and 21 L858R mutational subtypes was more challenging using PET/CT radiomics.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.18
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• pp.8589-8594
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• 2016

Background: Liver cancer is one of the most common causes of death in the world. In Korea, hepatitis B virus (HBV) is a major risk factor for liver cancer but infection rates have been declining since the implementation of the national vaccination program. In this study, we examined the secular trends in liver cancer mortality to distinguish the effects of age, time period, and birth cohort. Materials and Methods: Data for the annual number of liver cancer deaths in Korean adults (30 years and older) were obtained from the Korean Statistical Information Service for the period from 1984-2013. Joinpoint regression analysis was used to study the shapes of and to detect the changes in mortality trends. Also, an age-period-cohort model was designed to study the effect of each age, period, and birth cohort on liver cancer mortality. Results: For both men and women, the age-standardized mortality rate for liver cancer increased from 1984 to 1993 and decreased thereafter. The highest liver cancer mortality rate has shifted to an older age group in recent years. Within the same birth cohort group, the mortality rate of older age groups has been higher than in the younger age groups. Age-period-cohort analysis showed an association with a high mortality rate in the older age group and in recent years, whereas a decreasing mortality rate were observed in the younger birth cohort. Conclusions: This study confirmed a decreasing trend in liver cancer mortality among Korean men and women after 1993. The trends in mortality rate may be mainly attributed to cohort effects.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.8
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• pp.3893-3898
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• 2012

In previous studies we predicted future trends in cancer incidence for each prefecture in order to plan cancer control. Those predictions, however, did not take into account the characteristics of each prefecture. We therefore used the results of age-period-cohort analysis of incidence and mortality data of Osaka, and estimated the incidence and mortality of cancers at all sites and selected sites. The results reflect the characteristics of Osaka, which has and is expected to have large number of patients with liver cancer. We believe our results to be useful for planning and evaluating cancer control activities in Osaka. It would be worthwhile to base the estimation of cancer incidence and mortality in each prefecture on each population-based cancer registry.

• Journal of Preventive Medicine and Public Health
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• v.43 no.6
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• pp.543-548
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• 2010

Objectives: The objective of this study was to calculate sample size and power in an ongoing cohort, Korea radiation effect and epidemiology cohort (KREEC). Method: Sample size calculation was performed using PASS 2002 based on Cox regression and Poisson regression models. Person-year was calculated by using data from '1993-1997 Total cancer incidence by sex and age, Seoul' and Korean statistical informative service. Results: With the assumption of relative risk=1.3, exposure:non-exposure=1:2 and power=0.8, sample size calculation was 405 events based on a Cox regression model. When the relative risk was assumed to be 1.5 then number of events was 170. Based on a Poisson regression model, relative risk=1.3, exposure:non-exposure=1:2 and power=0.8 rendered 385 events. Relative risk of 1.5 resulted in a total of 157 events. We calculated person-years (PY) with event numbers and cancer incidence rate in the nonexposure group. Based on a Cox regression model, with relative risk=1.3, exposure:non-exposure=1:2 and power=0.8, 136 245PY was needed to secure the power. In a Poisson regression model, with relative risk=1.3, exposure:non-exposure=1:2 and power=0.8, person-year needed was 129517PY. A total of 1939 cases were identified in KREEC until December 2007. Conclusions: A retrospective power calculation in an ongoing study might be biased by the data. Prospective power calculation should be carried out based on various assumptions prior to the study.

• Journal of Preventive Medicine and Public Health
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• v.48 no.6
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• pp.280-286
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• 2015

Objectives: Approximately 10% to 15% of lung cancer cases occur in never-smokers. Hormonal factors have been suggested to lead to an elevated risk of lung cancer in women. This systematic review (SR) aimed to investigate the association between hormonal replacement therapy (HRT) and the risk of lung cancer in women using cohort studies. Methods: We first obtained previous SR articles on this topic. Based on these studies we made a list of refereed, cited, and related articles using the PubMed and Scopus databases. All cohort studies that evaluated the relative risk of HRT exposure on lung cancer occurrence in women were selected. Estimate of summary effect size (sES) with 95% confidence intervals (CIs) were calculated. Results: A total of 14 cohort studies were finally selected. A random effect model was applied due to heterogeneity (I-squared, 64.3%). The sES of the 14 articles evaluating the impact of HRT exposure on lung cancer occurrence in women indicated no statistically significant increase in lung cancer risk (sES, 0.99; 95% CI, 0.90 to 1.09). Conclusions: These results showed that HRT history had no effect on the risk of lung cancer in women, even though the sES of case-control studies described in previous SR articles indicated that HRT had a protective effect against lung cancer. It is necessary to conduct a pooled analysis of cohort studies.

• Korean Medical Education Review
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• v.25 no.2
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• pp.126-131
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• 2023

The aim of this study was to systematically collect data for evaluating short- and long-term outcomes using Kirkpatrick's four-level evaluation model, Chonnam National Medical School has established plans for developing and managing a database of student and graduate cohorts. The Education Evaluation Committee, with assistance from the Medical Education Office, manages the development and maintenance of cohort data. Data collection began in the 2022 academic year with first- through fourth-year medical students and graduates of the year 2022. The collected data include sociodemographic characteristics, admission information, psychological test results, academic performance data, extracurricular activity data, scholarship records, national medical licensing exam results, and post-graduation career paths. The Education Evaluation Committee and the Medical Education Office analyze the annually updated student and graduate cohort data and report the results to the dean and relevant committees. These results are used for admissions processes, curriculum improvement, and the development of educational programs. Applicants interested in using the student and graduate cohort data to evaluate the curriculum or conduct academic research must undergo review by the Educational Evaluation Committee before being granted access to the data. It is expected that the collected data from student and graduate cohorts will provide a sound and scientific basis for evaluating short- and long-term achievements based on student, school, and other characteristics, thereby supporting medical education policies, innovation, and implementation.

• Korean Medical Education Review
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• v.24 no.2
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• pp.156-171
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• 2022

The purpose of this study was to establish a model for constructing longitudinal data for medical school, and to structure cohort and longitudinal data using data from Yonsei University College of Medicine (YUCM) according to the established input-environment-output (I-E-O) model. The study was conducted according to the following procedure. First, the data that YUCM has collected was reviewed through data analysis and interviews with the person in charge of each questionnaire. Second, the opinions of experts on the validity of the I-E-O model were collected through the first expert consultation, and as a result, a model was established for each stage of medical education based on the I-E-O model. Finally, in order to further materialize and refine the previously established model for each stage of medical education, secondary expert consultation was conducted. As a result, the survey areas and time period for collecting longitudinal data were organized according to the model for each stage of medical education, and an example of the YUCM cohort constructed according to the established model for each stage of medical education was presented. The results derived from this study constitute a basic step toward building data from universities in longitudinal form, and if longitudinal data are actually constructed through this method, they could be used as an important basis for determining major policies or reorganizing the curricula of universities. These research results have implications in terms of the management and utilization of existing survey data, the composition of cohorts, and longitudinal studies for many medical schools that are conducting surveys in various areas targeting students, such as lecture evaluation and satisfaction surveys.

• Korea journal of population studies
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• v.35 no.1
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• pp.151-179
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• 2012

This study investigates birth cohort and educational differences in the marital and fertility life course using the Hernes model. First, lifetime marriage rates remain high across birth cohorts but men in the youngest birth cohort(1965-74) experience a somewhat significant reduction in ever-marriage rates. Second, this study also finds educational differences in lifetime marriage rates across birth cohorts. The likelihood of being never married is particularly high for poorly educated men in the youngest birth cohort but women show the opposite pattern. Third, quantum changes in the fertility transition are more likely to be the changes in higher-order births, while the changes in first and second births are mainly tempo changes. Fourth, the negative association between education and fertility is significantly larger for higher-order births. Finally, marriage and fertility show the opposite pattern in their association with education. Overall, educational differences in lifetime marriage rates become stronger across birth cohorts but the association between education and higher-order births shows the opposite pattern.

• Korean Medical Education Review
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• v.24 no.3
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• pp.250-260
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• 2022

Evaluating the effectiveness of educational programs involves measuring learning processes as well as outcomes. It is essential to study cohorts of students and graduates to evaluate the long-term effects of educational programs with data generated both during education and after graduation. The purpose of this study was to establish cohorts of students and graduates to evaluate their performance, thereby providing a basis for evaluating the social accountability of medical education. In this study, student and graduate cohorts were built for both students currently enrolled and graduates at Inje University College of Medicine (IUCM). A model involving the process of cohort establishment and an evaluation indicator framework was developed. In the process of cohort establishment, the following steps were conducted: defining the goals and objectives of the student and graduate cohorts, organizing a cohort committee, developing regulations, registering cohorts, acquiring consent, and building a database. A framework of evaluation indicators according to the graduate roles of IUCM was developed by adapting Kirkpatrick's evaluation model. Next, items to be collected in student and graduate cohorts were selected, and the current status of existing data was analyzed. Moreover, a preliminary analysis was conducted, including analyses of the evaluation indicators and graduates' performance. This study suggests that it is necessary to include additional evaluation indicators considering students' learning environment and well-being in student cohorts and to develop strategies or methods for graduates to continue participating in data collection for a long-term study.