• 한국환경보건학회지
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• 제37권5호
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• pp.342-347
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• 2011

Healthy worker effect (HWE) refers to the consistent tendency for actively employed individuals to have a more favorable mortality experience than the population at large. Although HWE has been well known since the 1970s, only a few studies in occupational epidemiology have attempted to fully define and evaluate HWE. HWE can be separated into effects on the initial hiring into the workforce (healthy worker hire effect) and those on continuing employment (healthy worker survival effect). In this review, we summarize the methods for minimizingor adjusting for the healthy worker effect available in occupational epidemiology. It is noteworthy that healthy worker survival effect appears complicated, considering that employment status plays simultaneous roles as a counfounding variable and intermediate variable, whereas healthy worker hire effect may be adjusted by incorporating health status at baseline into the statistical model. In addition, two retrospective cohort studies for workers in the semiconductor industry and Vietnam veterans in Korea, respectively, were introduced, and their results were explained in terms of healthy worker effect.

• Journal of Korean Dental Science
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• 제9권1호
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• pp.28-34
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• 2016

Purpose: The purpose of the present retrospective cohort study was to investigate the incidence of sinus perforation during endodontic microsurgery and to assess healing of cases with sinus perforation. Materials and Methods: Clinical and radiographic records were collected from patients who were treated with endodontic microsurgery in the Microscope Center of the Department of Conservative Dentistry at Yonsei University College of Dentistry, Seoul, Korea, between March 2001 and January 2016. To determine the incidence of sinus perforation, all cases involving maxillary premolar and molar teeth were assessed, and cases with perforation of maxillary sinus during the procedure were counted. To assess the outcome of the endodontic microsurgery, cases with sinus perforation were recalled at least 1 year after surgery. Result: Two hundred and forty-nine maxillary premolars and molars were treated with endodontic microsurgery. Among these cases, 16 cases had sinus perforations. Overall incidence of sinus perforation was 6.4%. Thirteen cases with sinus perforation were followed up for 1 year after endodontic microsurgery. Outcome assessment revealed that 2 of 13 cases with sinus perforation had failed. The success rate of endodontic microsurgery with sinus perforation was 84.6%. Conclusion: Endodontic surgery performed using microsurgical techniques decreases the risk of sinus perforation. Predictable outcomes of endodontic microsurgeries and healing of sinus membrane can be expected with adequate treatment steps and careful periodic follow-ups in cases with maxillary sinus perforations.

• Safety and Health at Work
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• 제2권3호
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• pp.243-249
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• 2011

Objectives: Cement contains hexavalent chromium, which is a human carcinogen. However, its effect on cancer seems inconclusive in epidemiologic studies. The aim of this retrospective cohort study was to elucidate the association between dust exposure in the cement industry and cancer occurrence. Methods: The cohorts consisted of male workers in 6 Portland cement factories in Korea. Study subjects were classified into five groups by job: quarry, production, maintenance, laboratory, and office work. Cancer mortality and incidence in workers were observed from 1992 to 2007 and 1997-2005, respectively. Standardized mortality ratios and standardized incidence ratios were calculated according to the five job classifications. Results: There was an increased standardized incidence ratio for stomach cancer of 1.56 (27/17.36, 95% confidence interval: 1.02-2.26) in production workers. The standardized mortality ratio for lung cancer increased in production workers. However, was not statistically significant. Conclusion: Our result suggests a potential association between cement exposure and stomach cancer. Hexavalent chromium contained in cement might be a causative carcinogen.

• Journal of Preventive Medicine and Public Health
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• 제47권3호
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• pp.177-181
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• 2014

Objectives: A salmonellosis outbreak occurred within a community of Gyeongju residents who ingested catered food from a wedding in June 2009. We aimed to epidemiologically investigate the probable vehicle of the infection. Methods: We conducted a retrospective cohort study on 34 local residents who ingested the wedding food. Results: Among the 34 residents, 31 (91.2%) reported symptoms of infection after eating the food. Among all of the wedding foods, pan-fried foods were highly associated with the diarrheal attack rate. On bacteriological examination, Salmonella species were detected in the pan-fried foods among the leftover foods and in 17 of the 31 stool specimens from the cases. There were five different types of pan-fried foods, but the onset of symptoms was independent of the ingredients used. We found that the pan-fried food was prepared at a food store in Seoul and that eggs were a common ingredient. Conclusions: The major cause of the salmonellosis in this population was presumed to be the pan-fried food prepared with contaminated eggs. These food items might have been partially undercooked because of their irregular shape, which allowed the Salmonella species to survive and multiply before ingestion.

• Archives of Plastic Surgery
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• 제43권5호
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• pp.446-450
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• 2016

Background Perineal defects are commonly encountered during the treatment of conditions such as malignancy, infectious disease, and trauma. Covering large defects in the perineal area is challenging due to its complicated anatomy and the need for functional preservation. Methods Fourteen patients who underwent reconstructive surgery with multiple perforator flaps for defects >$100cm^2$ in the perineal area were included in this retrospective cohort study. Characteristics of the perforator flap operation and postoperative outcomes were reviewed. Results Reconstruction was performed using 2 perforator flaps for 13 patients and 3 perforator flaps for 1 patient. Internal pudendal artery perforator flaps were mainly used for covering the defects. The average defect size was $176.3{\pm}61.8cm^2$ and the average size of each flap was $95.7{\pm}31.9cm^2$. Six patients had minor complications, such as wound dehiscence and partial necrosis of the flap margin, which were corrected with simple revision procedures. Conclusions Multiple perforator flaps can be used to achieve successful reconstructions of large perineal defects that are difficult to reconstruct with other coverage methods.

• The Journal of Advanced Prosthodontics
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• 제7권4호
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• pp.329-337
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• 2015

PURPOSE. This retrospective study aims at the evaluation of implant-supported overdentures (IODs) supported by ceramo-galvanic double crowns (CGDCs: zirconia primary crowns + galvano-formed secondary crown). MATERIALS AND METHODS. In a private practice, 14 patients were restored with 18 IODs (mandible: 11, maxilla: 7) retained by CGDCs on 4 - 8 implants and annually evaluated for technical and/or biological failures/complications. RESULTS. One of the 86 inserted implants failed during the healing period (cumulative survival rate (CSR) implants: 98.8%). During the prosthetic functional period (mean: $5.9{\pm}2.2years$), 1 implant demonstrated an abutment fracture (CSR-abutments: 98.2%), and one case of peri-implantitis was detected. All IODs remained in function (CSR-denture: 100%). A total of 15 technical complications required interventions to maintain function (technical complication rate: 0.178 treatments/patients/year). CONCLUSION. Considering the small sample size, the use of CGDCs for the attachment of IODs is possible without an increased risk of technical complications. However, for a final evaluation, results from a larger cohort are required.

• Asian Pacific Journal of Cancer Prevention
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• 제13권3호
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• pp.791-794
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• 2012

A retrospective cohort study was carried out with 340 female breast cancer at a teaching university in northeast of Thailand recruited and followed-up until the end of 2006. Survival probabilities were estimated using the Kaplan-Meier method. 161 cases were alive after five years and 58 patients were lost to follow-up. The overall observed survival rates at 1, 3 and 5 years were 83.3%, 59.9% and 42.9%, respectively. When analysis was conducted for stage combined into 2 groups, early (stage I, II and unknown) and late (stage III and IV), the 5-year survival rate for early stage (60%; 95%CI: 0.51-0.67), was higher than for late stage (27%; 95%CI: 0.19-0.34) with high statistical significance (p<0.001). The hazard ratio of patients with stage IV was 11.6 times greater than for stage I (p=0.03). The findings indicate that the different stages of breast cancer markedly effect the overall survival rate.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제23권6호
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• pp.531-538
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• 2020

Purpose: Our aim was the longitudinal assessment of cyst size in fetuses with biliary cystic malformation (BCM) to explore its etiology and the possibility of antenatal differentiation between biliary atresia (BA) and congenital biliary dilatation (CBD). Methods: We conducted a retrospective review of all patients diagnosed antenatally with BCM from 1994 to 2014 at our institutions. Results: The study cohort comprised of three patients with BA and six with CBD. There were no significant differences in the gestational age and cyst size at the first detection of BCM between the two groups. In fetuses with CBD, the cyst size steadily increased as the gestational age advanced, while it fluctuated around 1.5 cm and remained below 2.1 cm in those with BA. However, the ratio of cystic area to fetal trunk area was approximately constant due to linear fetal growth in fetuses with CBD. Conclusion: Fetuses with BCM <2.1 cm in the late gestation period were more likely to have BA than CBD. Our observation of cyst enlargement with advancing gestational age in the CBD group was attributed solely to fetal growth. Biliary dilatation in fetuses with CBD and BA might be completed at the onset of BCM.

• 약학회지
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• 제59권6호
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• pp.245-250
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• 2015

Middle East respiratory syndrome - coronavirus infection has posed substantial threat to public health with extremely high mortality rate in 2015. Although there are no approved novel medications for coronavirus, several antiviral agents such as ribavirin and interferon have been tried to MERS patients according to the in-vitro inhibitory effect, therapeutic effect on the animal model and experience from the severe acute respiratory syndrome - coronavirus infection. The aim of this study is to evaluate the clinical evidence of the antiviral treatment for MERS-CoV infection. After systematically searching the medical literature databases, I found five studies described the clinical efficacy of antiviral treatment on MERS patients. All of them were about the combination therapy of ribavirin and interferon (IFN). Two of them were retrospective cohort studies with quality of evidence (QOE) II and the others were observational study and case reports with QOE III. As a result of critical appraisal, it is concluded that none of those studies represented confirmatory clinical evidence of the efficacy of ribavirin and interferon combination therapy on MERS patients. Although Omrani et al. represented that ribavirin and IFN treatment had significantly improved survival at 14 days, it was not enough time to conclude the effect.

• 한국직업건강간호학회지
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• 제24권2호
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• pp.67-75
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• 2015

Purpose: The objective of the present study was to evaluate the effects of occupational exposure to low dose organic solvents on the prevalence of cardiovascular risk factors. Methods: Study design was retrospective cohort study subjected on 191 exposures and 118 controls working in a petrochemical manufacture company. The eight indicators related to CVD risk were followed up for five years from 2008 to 2012. The risk level was compared during the follow up years and subject's characteristics, and the change of risk level were analyzed with repeated measures ANOVA and multiple logistic regression analysis. Results: At the start year 2008, the rate over cutoff value (ROCV) of BS (p<.001) and mean systolic BP (p=.017) were higher in organic solvent exposure group and the others showed no difference. And by the subject's characteristics, odds ratio of the ROCV of BS were higher in organic solvent exposure group and work shift group as 2.51 and 3.07. Comparing the results in 2012 to those of 2008, cardiovascular disease risk in organic solvent exposure group was about 1.5 times higher than that of in the control group. Conclusion: Gradual increase in the CVD risk was identified in organic solvent exposure group. However, the risk might be influenced by shift work and bad behaviors rather than organic solvent exposure.