• Journal of Environmental Health Sciences
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• v.37 no.5
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• pp.358-368
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• 2011

Objectives: In order to evaluate the association between occupational exposure to chloroethylene (TCE) and risk of non-Hodgkin lymphoma (NHL), we conducted a meta-analysis of retrospective cohort studies and casecontrol studies and attempted to summarize the evidence of the association from molecular-epidemiological studies and experiments with human cells. Methods: In the meta-analysis, we restricted the analysis to those studies with data for chlorinated solvents, degreasers, or TCE. Studies involving dry cleaners or launderers were excluded from the analysis because use of TCE as a dry cleaning fluid has been rare since the 1960s. The data were combined using a random-effects model to estimate the summary risks (OR and RR) and 95% confidence intervals (CIs). Molecular evidence of the effect of TCE on human immune system were also reviewed and summarized. Results: Occupational exposure to TCE was strongly associated with NHL among cohort studies (number of studies=13, summary RR=1.33, 95% CI=1.04-1.70) whereas the association was not statistically significant among case-control studies (number of studies=15, summary OR=1.10, 0.98-1.23). When exposure level was considered, it became statistically significant for the highest exposure level (number of studies=5, summary OR=1.70, 1.25-2.32). Molecular evidences showed that TCE exposure in human or cultured human cells may cause a significant decrease immune cell subsets and changes in hormone levels related to immune response. Conclusions: Our results from meta-analysis and additional molecular evidence suggest that occupational exposure to TCE may cause NHL. However, unmeasured potential confounding and unclear dose-response relationships warrant further study on the role of TCE exposure in NHL carcinogenesis.

• Journal of Korean Neurosurgical Society
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• v.63 no.6
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• pp.730-737
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• 2020

Objective : Spinal degeneration is a progressive disease, worsening over time. Lumbar degenerative disease (LDD) is a major spinal disease in elderly patients. Surgical treatment is considered for medically intractable patients with LDD and reoperation after primary surgery is not uncommon. The surgical outcome is occasionally unpredictable because of comorbidities. In the present study, the relationship between comorbidities and the incidence of reoperation for LDD over time was determined. Methods : The claims data of the health insurance national database were used to identify a cohort of patients who underwent spinal surgery for LDD in 2009. The patients were followed up until 2016. Medical comorbidity was assessed according to the Charlson comorbidity index (CCI). Cox proportional hazard regression modeling was used to identify significant differences in sex, surgery, age, causative disease, and comorbidity. Results : The study cohort included 78241 patients; 10328 patients (13.2%) underwent reoperation during the observation period. The reoperation rate was statistically higher (p<0.01) in males, patients 55-74 years and 65-74 years of age, and patients with decompression or discectomy. Significant association was found between increasing reoperation rate and CCI score (p<0.01). Based on multivariate analysis of comorbidities, the significantly higher reoperation rates were observed in patients with peripheral vascular disease, pulmonary lung disease, peptic ulcer, diabetes, and diabetes complications (p<0.01). Conclusion : The study results indicate the reoperation rate for LDD is associated with patient comorbidities. The comorbidities identified in this study could be helpful in future LDD studies.

• Safety and Health at Work
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• v.2 no.2
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• pp.135-147
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• 2011

Objectives: The purpose of this study was to evaluate cancer risks in the Korean semiconductor industry. Methods: A retrospective cohort study was performed in eight semiconductor factories between 1998 and 2008. The number of subjects was 113,443 for mortality and 108,443 for incidence. Standardized mortality ratios (SMR) and standardized incidence ratios (SIR) were calculated. Results: The SMR of leukemia was 0.39 (95% Confidence Interval 0.08-1.14) in males (2 cases) and 1.37 (0.55-2.81) in females (7 cases). The SMR of non-Hodgkin's lymphoma (NHL) was 1.33 (0.43-3.09, 5 cases) in males and 2.5 (0.68-6.40, 4 cases) in females. The SIR of leukemia was 0.69 (0.30-1.37, 8 cases) in males and 1.28 (0.61-2.36, 10 cases) in females. The SIR of NHL in females was 2.31 (1.23-3.95, 13 cases) and that of thyroid cancer in males was 2.11 (1.49-2.89, 38 cases). The excess incidence of NHL was significant in female assembly operators [SIR=3.15 (1.02-7.36, 5 cases)], but not significant in fabrication workers. The SIR of NHL in the group working for 1-5 years was higher than the SIR of NHL for those working for more than five years. The excess incidence of male thyroid cancer was observed in both office and manufacturing workers. Conclusion: There was no significant increase of leukemia in the Korean semiconductor industry. However, the incidence of NHL in females and thyroid cancer in males were significantly increased even though there was no definite association between work and those diseases in subgroup analysis according to work duration. This result should be interpreted cautiously, because the majority of the cohort was young and the number of cases was small.

• Archives of Craniofacial Surgery
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• v.22 no.5
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• pp.254-259
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• 2021

Background: Prophylactic antibiotics are commonly used in craniofacial surgeries. Despite the low risk of surgical site infection after nasal surgery, a lack of consensus regarding the use of antibiotic prophylaxis in the closed reduction of nasal bone fractures has led to inappropriate prescribing patterns. Through this study, we aimed to investigate the status of prophylactic antibiotic use in closed reductions of nasal bone fractures in Korea. Methods: This retrospective cohort study was conducted using data from the National Health Insurance Service-National Sample Cohort of Korea from 2005 to 2015. We analyzed the medical records of patients who underwent closed reduction of nasal bone fractures. The sex, age, region of residence, comorbidities, and socioeconomic variables of the patients were collected from the database. Factors that affect the prescription of perioperative antibiotics were evaluated using multivariate logistic regression analysis. Results: A total of 3,678 patients (mean±standard deviation of age, 28.7±14.9 years; 2,850 men [77.5%]; 828 women [22.5%]) were included in this study. The rate of antibiotic prescription during the perioperative period was 51.4%. Approximately 68.8% of prescriptions were written for patients who had received general anesthesia. The odds of perioperative prophylactic antibiotic use were significantly higher in patients who received general anesthesia than who received local anesthesia (odds ratio, 1.59). No difference was found in terms of patient age and physician specialty. Second-generation cephalosporins were the most commonly prescribed antibiotic (45.3%), followed by third- and first-generation cephalosporins (20.3% and 18.8%, respectively). In contrast, lincomycin derivatives and aminoglycosides were not prescribed. Conclusion: The findings of this study showed that there was a wide variety of perioperative antibiotic prescription patterns used in nasal bone surgeries. Evidence-based guidance regarding the prescribing of antimicrobial agents for the closed reduction of nasal bone fractures should be considered in future research.

• Journal of Periodontal and Implant Science
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• v.49 no.3
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• pp.158-170
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• 2019

Purpose: This study investigated the association between health status and tooth loss based on data from the National Health Insurance Service-Health Examinee Cohort in 2002-2015. Methods: Multivariate Cox proportional hazards regression analyses were applied to a longitudinal retrospective database, which was updated and newly released in 2018, to assess the association between health status and tooth loss while adjusting for potential confounders among sociodemographic and economic factors (sex, age, household income, insurance, and presence of disability), general and oral health status (body mass index [BMI], smoking and drinking status, periodic dental visits and scaling, and brushing before sleep), and comorbid disease (hypertension, diabetes mellitus [DM], and Charlson comorbidity index [CCI]). Results: Among 514,866 participants from a South Korean population, 234,247 (45.5%) participants satisfying the inclusion criteria were analyzed. In the adjusted multivariate analysis, sex, age, household income, insurance, presence of disability, BMI, smoking and drinking status, periodic scaling, tooth brushing before sleep, DM, and CCI showed statistically significant associations with the loss of at least 1 tooth. The risk of experiencing a loss of ${\geq}4$ teeth was associated with an increase in age (in those 50-59 years of age: hazard ratio [HR], 1.98; 95% confidence interval [CI], 1.93-2.03; in those 60-69 years of age: HR, 2.93; 95% CI, 2.85-3.02; and in those 70-79 years of age: HR, 2.93; 95%, CI 2.81-3.05), smoking (HR, 1.69; 95% CI, 1.65-1.73), and DM (HR, 1.43; 95% CI, 1.38-1.48). Conclusions: The results of this study showed that the risk of experiencing tooth loss was related to multiple determinants. DM and smoking were especially significantly associated with tooth loss.

• Journal of muscle and joint health
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• v.27 no.3
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• pp.219-228
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• 2020

Purpose: This study was a comparative analysis of stroke-related factors between recurrent patients and non-recurrent patients. Methods: A retrospective cohort study design was used, and data were collected from March 2020 to April 2020 using electronic medical records. 244 patients (221 first-timers and 23 recurrent) were included in this study. Results: The stroke recurrence rate in 5 years was 9.4%, the readmission rate was 39.3%, and the mortality rate was 2.0%. The number of patients hospitalized for stroke was greater among men than among women. Of the patients, 60.7% had an underlying disease. With regard to daily life abilities, over 70% of participants needed more than moderate dependence and about 40% of participants had more than mild cognitive impairment. More than 50% were moved to wheelchairs or stretcher cars. The difference in the stroke readmission rate between recurrent and non-recurrent patients was statistically significant. Conclusions: Based on our findings, a program to prevent recurrence of stroke should be developed to considering age, ability of daily living, place of discharge, gait ability at discharge, and place of discharge.

• Journal of Society of Preventive Korean Medicine
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• v.25 no.3
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• pp.25-37
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• 2021

Objectives : To investigate the effectiveness of Korean Medicine services use on the all-cause mortality and incidence of Parkinson's disease(PD) in elderly patients with chronic disease based on the National Health Insurance Service Corhort Database (elderly), called as the NHIS-senior. Methods : This study was a retrospective cohort analysis conducted using the NHIS-senior. Patients with chronic diseases over 65 years old who were not diagnosed PD during 2007-2009 were identified. The case group was defined as patients who used both Korean Medicine and Western Medicine services and the control group consisted of patients who used Western Medicine service only. The all-cause mortality and incidence of PD was analyzed using the Cox proportional hazard model after a propensity score matching(PSM) with a 1:1 ratio. Results : After PSM, the cohort included 47,546 subjects (23,773 in the case group, 23,773 in the control group). Sex, age, comorbidity, severity of disability, and neurology medical service utilization were adjusted in both groups. The mortality was 0.668 times (95% C.I.: 0.646-0.690) lower in the case group than the control group, which was statistically significant (p<0.001). The incidence of PD was 1.051 times (95% C.I.: 0.962-1.148) higher in the case group than the control group, which was not statistically significant(p=0.272). Conclusion : It was not obvious that the use of both Korean Medicine service and Western Medicine services for prevention of PD is benefitial than using only Western Medicine. But it would be possible that using both Korean Medicine and Western Medicine services decreases the mortality than using Western Medicine alone.

• Safety and Health at Work
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• v.14 no.3
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• pp.279-286
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• 2023

Background: This study aimed to evaluate the association between exposure to occupational hazards and the metabolic syndrome. A secondary objective was to analyze the additive and multiplicative effects of exposure to risk factors. Methods: This retrospective cohort was based on 31,615 health examinees at the Pusan National University Yangsan Hospital in Republic of Korea from 2012-2021. Demographic and behavior-related risk factors were treated as confounding factors, whereas three physical factors, 19 organic solvents and aerosols, and 13 metals and dust were considered occupational risk factors. Time-dependent Cox regression analysis was used to calculate hazard ratios. Results: The risk of metabolic syndrome was significantly higher in night shift workers (hazard ratio = 1.45: 95% confidence interval = 1.36-1.54) and workers who were exposed to noise (1.15:1.07-1.24). Exposure to some other risk factors was also significantly associated with a higher risk of metabolic syndrome. They were dimethylformamide, acetonitrile, trichloroethylene, xylene, styrene, toluene, dichloromethane, copper, antimony, lead, copper, iron, welding fume, and manganese. Among the 28 significant pairs, 19 exhibited both positive additive and multiplicative effects. Conclusions: Exposure to single or combined occupational risk factors may increase the risk of developing metabolic syndrome. Working conditions should be monitored and improved to reduce exposure to occupational hazards and prevent the development of the metabolic syndrome.

• Korean Journal of Radiology
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• v.22 no.6
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• pp.912-921
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• 2021

Objective: To compare the performance of the deep learning-based lesion detection algorithm (DLLD) in detecting liver metastasis with that of radiologists. Materials and Methods: This clinical retrospective study used 4386-slice computed tomography (CT) images and labels from a training cohort (502 patients with colorectal cancer [CRC] from November 2005 to December 2010) to train the DLLD for detecting liver metastasis, and used CT images of a validation cohort (40 patients with 99 liver metastatic lesions and 45 patients without liver metastasis from January 2011 to December 2011) for comparing the performance of the DLLD with that of readers (three abdominal radiologists and three radiology residents). For per-lesion binary classification, the sensitivity and false positives per patient were measured. Results: A total of 85 patients with CRC were included in the validation cohort. In the comparison based on per-lesion binary classification, the sensitivity of DLLD (81.82%, [81/99]) was comparable to that of abdominal radiologists (80.81%, p = 0.80) and radiology residents (79.46%, p = 0.57). However, the false positives per patient with DLLD (1.330) was higher than that of abdominal radiologists (0.357, p < 0.001) and radiology residents (0.667, p < 0.001). Conclusion: DLLD showed a sensitivity comparable to that of radiologists when detecting liver metastasis in patients initially diagnosed with CRC. However, the false positives of DLLD were higher than those of radiologists. Therefore, DLLD could serve as an assistant tool for detecting liver metastasis instead of a standalone diagnostic tool.

• Journal of Preventive Medicine and Public Health
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• v.57 no.1
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• pp.55-64
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• 2024

Objectives: This study investigated the prevalence and characteristics of comorbid conditions in patients exposed to ionizing radiation and those who were involved in the Soviet-Afghan war. Methods: This study analyzed the frequency and spectrum of morbidity and comorbidity in patients over a long-term period (30-35 years) following exposure to ionizing radiation at the Semipalatinsk nuclear test site or the Chornobyl nuclear power plant, and among participants of the Soviet-Afghan war. A cohort study, both prospective and retrospective, was conducted on 675 patients who underwent comprehensive examinations. Results: Numerical data were analyzed using the Statistica 6 program. The results are presented as the mean±standard deviation, median, and interquartile range (25-75th percentiles). The statistical significance of between-group differences was assessed using the Student t-test and Pearson chi-square test. A p-value of less than 0.05 was considered statistically significant. We found a high prevalence of cardiovascular diseases, including hypertension (55.0%) and cardiac ischemia (32.9%); these rates exceeded the average for this age group in the general population. Conclusions: The cumulative impact of causal occupational, environmental, and ultra-high stress factors in the combat zone in participants of the Soviet-Afghan war, along with common conventional factors, contributed to the formation of a specific comorbidity structure. This necessitates a rational approach to identifying early predictors of cardiovascular events and central nervous system disorders, as well as pathognomonic clinical symptoms in this patient cohort. It also underscores the importance of selecting suitable methods and strategies for implementing treatment and prevention measures.