• The Journal of Health Technology Assessment
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• v.6 no.2
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• pp.142-147
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• 2018

Objectives: The purpose of this study is to evaluate the safety and effectiveness of Robot-Assisted Brain Stereotactic Surgery with a systematic review. Methods: Electronic literature was searched using KoreaMed, Ovid-MEDLINE, Ovid-EMBASE, and Cochrane Library on 6th April 2017. Two authors screened 1218 citations. Duplicated articles of 456 excluded, the remaining 762 articles were reviewed with title and abstract. Results: A total of 8 studies were selected in this review. The device used in all studies was $ROSA^{TM}$. In one cohort study comparing the intervention ($ROSA^{TM}$) with the control (conventional stereotactic surgery), hematoma was reported no significant difference between groups. In six descriptive studies, one study reported hematoma 10% (10/100) and temporary nerve impairment 6% (6/100) using the ROSA; while five descriptive study did not report any complications. In one cohort, the localization precision were 1.2 mm in the intervention group and 1.1 mm in the control group; the localization success rate as 78.2% in the intervention group and 76.2% in the control group in one cohort; and the average time for surgery as 130 min for the intervention group and 352 min for the control group in one cohort. Four studies reported the localization success rate as 100%; two out of three articles reported the overall time for surgery as 56 min and 90 min, while one article reported the time as less than one hour in 50% of patients (50/100); two articles reported in epilepsy patients, the condition after the surgery was Engel level I in 66.2%, 75% patients, Engel level II-III in 25%, 26.5% patients, and Engel level 4 in 7.3% patients. Conclusion: Robot-Assisted Brain Stereotactic Surgery is a safe and accurate technique that can significantly reduce the time for the brain stereotactic surgery. However, further studies are needed to generalize the results.

• Journal of Cancer Prevention
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• v.23 no.4
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• pp.183-190
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• 2018

Background: As the number of big-cohort studies increases, validation becomes increasingly more important. We aimed to validate administrative database categorized as colorectal cancer (CRC) by the International Classification of Disease (ICD) 10th code. Methods: Big-cohort was collected from Clinical Data Warehouse using ICD 10th codes from May 1, 2003 to November 30, 2016 at Seoul National University Bundang Hospital. The patients in the study group had been diagnosed with cancer and were recorded in the ICD 10th code of CRC by the National Health Insurance Service. Subjects with codes of inflammatory bowel disease or tuberculosis colitis were selected for the control group. For the accuracy of registered CRC codes (C18-21), the chart, imaging results, and pathologic findings were examined by two reviewers. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for CRC were calculated. Results: A total of 6,780 subjects with CRC and 1,899 control subjects were enrolled. Of these patients, 22 subjects did not have evidence of CRC by colonoscopy, computed tomography, magnetic resonance imaging, or positron emission tomography. The sensitivity and specificity of hospitalization data for identifying CRC were 100.00% and 98.86%, respectively. PPV and NPV were 99.68% and 100.00%, respectively. Conclusions: The big-cohort database using the ICD 10th code for CRC appears to be accurate.

• Journal of Preventive Medicine and Public Health
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• v.51 no.6
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• pp.281-288
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• 2018

Objectives: We investigated the association between cholecystectomy or appendectomy and the subsequent risk of colorectal cancer (CRC) in the Korean population. Methods: A retrospective cohort study was conducted with the National Health Insurance Service-National Sample Cohort of Korea; this sample was followed up from January 1, 2002, until the date of CRC incidence, loss to follow-up, or December 31, 2015. The exposure status of cholecystectomy and appendectomy was treated as a time-varying covariate. The calculated risk of CRC was stratified by follow-up period, and the association between these surgical procedures and CRC was investigated by a Cox regression model applying appropriate lag periods. Results: A total of 707 663 individuals were identified for analysis. The study population was followed up for an average of 13.66 years, and 4324 CRC cases were identified. The hazard ratio (HR) of CRC was elevated in the first year after cholecystectomy (HR, 1.71; 95% confidence interval [CI], 1.01 to 2.89) and in the first year and 2-3 years after appendectomy (HR, 4.22; 95% CI, 2.87 to 6.20; HR, 2.34; 95% CI, 1.36 to 4.03, respectively). The HRs of CRC after applying 1 year of lag after cholecystectomy and 3 years of lag after appendectomy were 0.80 (95% CI, 0.57 to 1.13) and 0.77 (95% CI, 0.51 to 1.16), respectively. Conclusions: The risk of CRC increased in the first year after cholecystectomy and appendectomy, implying the possibility of bias. When appropriate lag periods after surgery were applied, no association was found between cholecystectomy or appendectomy and CRC.

• Tuberculosis and Respiratory Diseases
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• v.82 no.4
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• pp.311-318
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• 2019

Background: Although physical activity is known to be beneficial to lung function, few studies have been conducted to investigate the correlation between physical activity and lung function in dusty areas. Therefore, the purpose of this study is to investigate the correlation between physical activity and lung function in a Korean cohort including normal and COPD-diagnosed participants. Methods: Data obtained from the COPD in dusty areas (CODA) cohort was analyzed for the following factors: lung function, symptoms, and information about physical activity. Information on physical activity was valuated using questionnaires, and participants were categorized into two groups: active and inactive. The evaluation of the mean lung function, modified Medical Research Council dyspnea grade scores, and COPD assessment test scores was done based on the participant physical activity using a general linear model after adjusting for age, sex, smoking status, pack-years, height, and weight. In addition, a stratification analysis was performed based on the smoking status and COPD. Results: Physical activity had a correlation with high forced expiratory volume in 1 second ($FEV_1$) among CODA cohort (p=0.03). While the active group exhibited significantly higher $FEV_1$ compared to one exhibited by the inactive group among past smokers (p=0.02), no such correlation existed among current smokers. There was no significant difference observed in lung function after it was stratified by COPD. Conclusion: This study established a positive correlation between regular physical activity in dusty areas and lung function in participants.

• Journal of Periodontal and Implant Science
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• v.51 no.2
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• pp.114-123
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• 2021

Purpose: This retrospective cohort study aimed to assess the effect of nonsurgical periodontal therapy on glycated hemoglobin (HbA1c) levels in patients with both type 2 diabetes and chronic periodontitis. Methods: The intervention cohort (IC) comprised 133 patients with type 2 diabetes who received nonsurgical periodontal treatment, while the matching cohort (MC) included 4787 patients with type 2 diabetes who visited the Department of Endocrinology and Metabolism of Asan Medical Center. The patients in each cohort were divided into 3 groups according to their baseline HbA1c level: subgroup 1, HbA1c <7%; subgroup 2, 7%≤ HbA1c <9%; and subgroup 3, HbA1c ≥9%. Changes in HbA1c levels from baseline to 6 and 12 months were analyzed. In addition, the association between changes in HbA1c levels and the number of periodontal maintenance visits was investigated. Results: There were no statistically significant changes in HbA1c levels in the IC and MC or their subgroups when evaluated with repeated-measures analysis of variance. However, the IC showed maintenance of baseline HbA1c levels, while the MC had a trend for HbA1c levels to steadily increase as shown by pairwise comparisons (baseline to 6 months and baseline to 12 months). IC subgroup 1 also maintained steady HbA1c levels from 6 months to 12 months, whereas MC subgroup 1 presented a steady increase during the same period. The number of periodontal maintenance visits had no association with changes in HbA1c levels during the 1-year study duration. Conclusions: For patients with both type 2 diabetes and periodontitis, nonsurgical periodontal treatment and periodontal maintenance may help to control HbA1c levels.

• Journal of Gastric Cancer
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• v.21 no.1
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• pp.49-62
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• 2021

Purpose: This study aimed to investigate the prognostic value of lymph node ratio (LNR) in patients with locally advanced gastric cancer who received neoadjuvant chemotherapy. Materials and Methods: We retrospectively enrolled gastric cancer patients treated with neoadjuvant chemotherapy and curative surgery at the First Affiliated Hospital of Zhejiang University from 2004 to 2015 as the study cohort. Patients with the same inclusion criteria treated in 2016-2017 were enrolled as the validation cohort. Kaplan-Meier curves were assessed using the log-rank test to analyze the differences in overall survival (OS). Multivariate survival analysis was performed using the Cox proportional hazards model. The areas under the receiver operating characteristic curve of ypN and LNR categories for predicting the actual 3-year OS were compared. Results: A total of 265 patients were included in the proposal cohort. The median number of retrieved lymph nodes (rLNs) was 32. The number of positive lymph nodes (pLNs) increased as rLN increased (P=0.037), but the LNR remained relatively constant (P=0.462). The LNR was categorized into 4 groups according to the prognosis: ypNr0, node-negative with rLN>25; ypNr1, node-negative with rLN≤25 or 00.3. In the validation cohort of 43 enrolled patients, there was a clear distinction in OS that significantly (P<0.001) varied depending on the LNR values and LNR was the only independent prognostic factor in multivariate analysis (P<0.001). Conclusions: LNR was an independent prognostic factor for survival of patients with gastric cancer after preoperative chemotherapy and might be an alternative predictor for ypN stage.

• Safety and Health at Work
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• v.13 no.1
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• pp.112-116
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• 2022

Background/Aims: The Gachon Regional Occupational Cohort Study (GROCS) is a large-scale longitudinal study of occupational safety and health data (covering Work Environment Monitoring, Workers' Health Surveillance, and Occupational Health Service) conducted by the Gachon University Gil Medical Center (GUGMC) in Incheon, Republic of Korea. We conducted GROCS to identify the health effects of workers' occupational risks, behavior, socioeconomic status, and life style. Methods: The GROCS includes data from Work Environment Monitoring, Workers' Health Surveillance, and Occupational Health Service. The baseline year for all data collection was 2018. Work Environment Monitoring was conducted in 240 companies located in Incheon. General Health Examination and Special Health Examination were performed on 32,725 and 9,504 workers, respectively. Occupational Health Services were provided to 16,883 workers in 171 companies. These data have been collected and operated at an external data management institution and were provided as a retrospective cohort after removing personal identification information. Results: In 2018, the total number of companies was 2,854, among which which 488 special Health Examination, 171 Work Environment Monitoring, and 240 Occupational Health Service. The proportion of companies undergoing Special Health Examination was 17.1%, the proportion of companies undergoing Work Environment Monitoring was 8.4%, and the proportion of Companies undergoing Occupational Health Service was 6.0%. Conclusion: GROCS expects researchers to utilize its useful and reliable resource for occupational health and surveillance with for academic or political purposes to lead to improved workers' health and working environment.

• 한국노년학
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• v.41 no.3
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• pp.397-420
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• 2021

The paper tried to determine relationships between volunteering and hypertension risks, symptom betterment, activity difficulty occurrences, and medicine treatment among middle-aged and older adults, with a prospective cohort study. Multilevel mixed-effects generalized linear models were used for the analysis of longitudinal panel data collected over 10 years from 2008 to 2018, using 5,867 cohort samples. The results showed that those who volunteered at least 200 hours per year were 3.4 times more lower than not-volunteering in risks of hypertension, those who volunteered yearly 50~99 hours were a lot more improved than not-volunteering in the symptom betterment, those who volunteered yearly at least 200 hours were 7.7 times lower than not-volunteering in activity difficulty occurrences, and those who volunteered yearly 50~99 hours were 2.5 times lower than not-volunteering in the occurrences of medicine treatment. These indicate that volunteering among middle-aged and older adults may have health benefits against incident hypertension. Finally the thesis discusses the study limitations, future directions of studies, and the practices implications.

• Journal of International Area Studies (JIAS)
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• v.14 no.1
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• pp.309-330
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• 2010

This paper examines the life-cycle and birth cohort effect on East Asian supranational identity. This paper also explores how national identity is related with supranational identity among Koreans. Using the 2008 CCGA-EAI survey, we analyze the determinants of supranational East Asian identity. The results suggest several interesting findings. Age and national identity have positive effects on East Asian identity. Among generational cohorts, the democratization cohort were less likely than other cohorts to have East Asian identity. These findings suggest several implications. First, in Korea, unlike other countries in the Western world, the older tend to have stronger regional identity than the younger do. Second, unlike the existing literature, this paper finds that strong national identity (pride) is complementary, rather than substitutive, to supranational regional identity. This warrants further systematic research on the microfoundation on the relationship between regional integration and nationalism in Northeast Asia.

• Economic Analysis
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• v.26 no.3
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• pp.48-70
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• 2020

Using data from the Household Income and Expenditure Survey over the period 1994-2016, we estimate the coefficient of relative prudence in order to capture precautionary saving motive. To do this, we adopt a cohort approach, where we transform such microdata into sample cohort means. Together with initial income involving liquidity constraint, we estimate the relative prudence derived from the Euler equation. The two-stage least-squares (2SLS) between estimate of it obtained from the cohort panel data analysis is too small for the existence of precautionary saving motive, as in previous studies, while the 2SLS random effects estimate is so reasonable. Moreover, the liquidity-constrained cohorts tend to be more sensitive to uncertainty, relative to the unconstrained ones.