• 한국산업보건학회지
• /
• 제31권4호
• /
• pp.367-377
• /
• 2021

Objectives: Taxi drivers are exposed to various hazards, such as long periods of sedentary work and traffic-related air pollutants. However, studies on the health effects among taxi drivers in South Korea are insufficient. Methods: To assess subclinical hematologic change related to cardiovascular disease among male taxi drivers, we analyzed data from the second Korean National Environmental Health Survey. Fifty-nine taxi drivers and 1,912 controls were included in the analysis. Propensity score matching was performed to adjust for age, body mass index, and urinary cotinine. A total of 295 subjects were matched with 59 taxi drivers. Leukocyte count, platelet count, hematocrit, triglyceride, total cholesterol, HDL cholesterol land total IgE of the taxi drivers were compared with the control groups. Results: Taxi drivers showed significantly elevated blood leukocytes and platelets. Serum total IgE was significantly reduced in taxi drivers. However, blood leukocytes, platelets, and serum total IgE were not significantly correlated with work period among taxi drivers. Conclusions: Regarding the change of the blood leukocyte count, platelet count, and serum total IgE, taxi driving has the possibility to be associated with peripheral inflammation, humoral immunity and cardiovascular risk.

• 농촌계획
• /
• 제30권1호
• /
• pp.81-97
• /
• 2024

This study examines the effects of adopting Information and Communication Technology (ICT) in livestock farm management on farm sales revenue. Using the 2020 Census of Agriculture, Forestry, and Fisheries, a nationally representative data set constructed by Statistics Korea, this study focuses on a sample of 9,020 livestock farms in South Korea. We employ Propensity Score Matching (PSM) methods to address the potential selection bias between 2,076 farms that used ICT for livestock farm management and 6,944 farms that did not. The findings consistently show that the use of ICT significantly increases farm revenue, taking into account the selection bias. The utilization of ICT in livestock farms leads to a higher increase in sales revenue, particularly for farms with greater sales.

• 응용통계연구
• /
• 제27권7호
• /
• pp.1077-1095
• /
• 2014

관찰연구를 이용하여 인과관계를 추론할 경우 무작위 통제시험과는 달리 교란변수로 인한 편향을 제어하기 위한 통계적 전략이 필요하다. 최근에는 성향점수(propensity score) 를 이용한 짝짓기나 원인변수의 역확률을 가중치로 사용하는 주변구조모형이 제안되어 사용되고 있다. 이러한 인과관계 추론은 처치(treatment)가 명확히 주어진 경우에 교란변수를 통제하고 그 처치가 결과에 미치는 영향을 평가하는 방법에 초점이 맞추어져 있다. 하지만 기존의 방법의 경우 원인변수인 처치가 직접관측이 가능한 범주형 변수이고 결과변수 또한 직접관측이 가능한 변수인 경우에만 사용할 수 있는 한계를 갖고 있다. 본 연구에서는 원인변수인 처치와 결과변수의 결괏값의 직접적인 관측이 어려운 경우, 측정오차를 고려한 잠재범주모형(latent class analysis)의 변수로 모형화 함으로써 잠재범주 간의 원인적 영향력을 추정하는 방법을 제시하고자 한다. 그리고 미국의 The National Longitudinal Study of Adolescent Health 자료를 이용하여, 약물사용의 잠재범주에 대한 청소년기의 비행(delinquency)이라는 잠재범주의 원인적 영향력을 추정하였다.

• 응용통계연구
• /
• 제30권5호
• /
• pp.615-632
• /
• 2017

무작위 통제시험에서와 달리, 관찰연구에서는 편향되지 않은 인과관계를 추론하기 위한 통계적 전략이 필요하다. 최근 잠재범주분석(latent class analysis; LCA)에서 처치의 평균인과효과(average causal effect; ACE)를 추정하기 위한 새로운 방법들이 제안되었으나 이러한 방법들은 실제 데이터를 분석하는 응용 연구에 초점이 맞춰있다. 따라서 ACE의 참값을 알 수 없어 추정 방법의 성능을 평가하는 데 한계가 있다. 본 연구에서는 Park과 Chung(2014)이 제안한 방법을 개선하여, 다항범주형 처치변수가 잠재변수인 상황에서 다항범주형 결과변수에 미치는 인과효과 추정방법을 제안하고 처치변수와 결과변수가 잠재변수 또는 관측변수를 포함하는 여러 상황에서 본 연구가 제안한 인과효과 추정방법의 성능을 모의실험연구를 통하여 평가하고자 한다. 더불어 'National Longitudinal Study of Adolescents Health'자료를 사용하여 미국 여성 청소년 성장과 약물사용에 대한 인과효과를 추론하고자 한다.

• Journal of Preventive Medicine and Public Health
• /
• 제57권1호
• /
• pp.1-7
• /
• 2024

Objectives: Adjusting for potential confounders is crucial for producing valuable evidence in outcome studies. Although numerous studies have been published using the Korea National Health Insurance Claim Database, no study has critically reviewed the methods used to adjust for confounders. This study aimed to review these studies and suggest methods and applications to adjust for confounders. Methods: We conducted a literature search of electronic databases, including PubMed and Embase, from January 1, 2021 to December 31, 2022. In total, 278 studies were retrieved. Eligibility criteria were published in English and outcome studies. A literature search and article screening were independently performed by 2 authors and finally, 173 of 278 studies were included. Results: Thirty-nine studies used matching at the study design stage, and 171 adjusted for confounders using regression analysis or propensity scores at the analysis stage. Of these, 125 conducted regression analyses based on the study questions. Propensity score matching was the most common method involving propensity scores. A total of 171 studies included age and/or sex as confounders. Comorbidities and healthcare utilization, including medications and procedures, were used as confounders in 146 and 82 studies, respectively. Conclusions: This is the first review to address the methods and applications used to adjust for confounders in recently published studies. Our results indicate that all studies adjusted for confounders with appropriate study designs and statistical methodologies; however, a thorough understanding and careful application of confounding variables are required to avoid erroneous results.

• 기술혁신학회지
• /
• 제13권3호
• /
• pp.446-458
• /
• 2010

세계 각국은 과거부터 경제성장과 성장동력의 확보를 위해 꾸준히 외국인직접투자를 유치해왔으며 이는 우리나라도 예외가 아니다. 실제로, 각종 정책적 지원을 통해 양질의 투자를 유치하고 있고, 정부차원에서도 하나의 성과로 홍보하고 있다. 기존의 연구가 대부분 국가경제적 차원에서 외국인직접투자의 성과를 분석하고 있는 것에 그치고 있는 것에 착안, 본 연구는 이러한 외국인직접투자가 기업의 경영성과와 혁신성과에 긍정적인 효과를 미칠 것으로 가정하고 PSM 방법을 통해 실증분석을 하였다. 분석결과 매칭 전에는 외국인직접투자가 경영성과와 혁신성에 모두 양(+)의 효과를 미치는 것으로 나타났으나, 매칭 후에는 모두 통계적 유의성을 상실하여 외국인직접투자가 기업에 미치는 긍정적인 효과가 생각보다 부진하다는 것을 알 수 있었다. 이러한 분석결과는 정부의 외국인직접투자 인센티브 효과가 기대했던 것에 비해 적으며, 추후 정책에 대한 개선이 필요한 것으로 판단할 수 있다.

• 한국산학기술학회논문지
• /
• 제18권5호
• /
• pp.581-586
• /
• 2017

사과, 배, 포도 등 과수 고품질 생산과 생산성 향상을 위한 시설현대화 정책은 사업 참여농가들의 생산량이 증가하는 등 사업의 성과가 높은 것으로 보고되고 있어, 생산농가의 정책 참여의향이 높은 것으로 보인다. 그 동안 이 사업에 참여한 생산농가는 품종갱신, 친환경과원관리, 배수시설, 지주시설, 관수관비시설, 비가림시설, 다겹보온커텐설치, 작업로 정비, 야생동물 방지시설, 서리피해방지시설 등 여러 사업에 참여했다. 이 논문은 우리나라 과수산업에서 생산비중이 높은 품목(사과, 배, 포도) 생산농가를 대상으로 정책수행의 성과를 측정하였다. 우리는 이를 위해 참여농가 약 300호를 대상으로 설문조사를 실시하였다. 설문조사 자료를 토대로 공변량매칭 및 PSM 방법을 이용하여, 생산량, 농가판매가격, 당도 증가율, 생산비 등 다양한 변수들에 대한 사업 전후의 성과 변화를 비교 검토하였다. 검토결과, 여러 세부 사업 중 사과의 경우는 주로 품종갱신, 배는 주로 관수관비시설 설치, 포도는 비가람시설의 설치사업에 주로 참여하여 양적 생산량 증대는 물론 당도개선 등 과실의 품질향상에도 상당한 기여를 한 것으로 파악된다.

• Journal of Gastric Cancer
• /
• 제19권2호
• /
• pp.193-201
• /
• 2019

Purpose: There is no consensus on the optimal method for intracorporeal esophagojejunostomy (EJ) in laparoscopic total gastrectomy (LTG). This study aims to compare 2 established methods of EJ anastomosis in LTG. Materials and Methods: A total of 314 patients diagnosed with gastric cancer that underwent LTG in the period from January 2013 to October 2016 were enrolled in the study. In 254 patients, the circular stapler with purse-string "Lap-Jack" method was used, and in the other 60 patients the linear stapling method was used for EJ anastomosis. After propensity score matching, 58 were matched 1:1, and retrospective data for patient characteristics, surgical outcome, and post-operative complications was reviewed. Results: The 2 groups showed no significant difference in age, body mass index, or other clinicopathological characteristics. After propensity score matching analysis, the linear group had shorter operating time than the circular group ($200.3{\pm}62.0$ vs. $244.0{\pm}65.5$, $P{\leq}0.001$). Early postoperative complications in the circular and linear groups occurred in 12 (20.7%) and 15 (25.9%, P=0.660) patients, respectively. EJ leakage occurred in 3 (5.2%) patients from each group, with 1 patient from each group needing intervention of Clavien-Dindo grade III or more. Late complications were observed in 3 (5.1%) patients from the linear group only, including 1 EJ anastomosis stricture, but there was no statistical significance. Conclusions: Both circular and linear stapling techniques are feasible and safe in performing intracorporeal EJ anastomosis during LTG. The linear group had shorter operative time, but there was no difference in anastomosis complications.

• Journal of Chest Surgery
• /
• 제45권2호
• /
• pp.80-84
• /
• 2012

Background: The aim of this study is to evaluate our institutional results of the aortic valve replacement through minimally invasive approaches compared with conventional sternotomy. Materials and Methods: From August 1997 to July 2010, 838 patients underwent primary isolated aortic valve replacement. Of them, 73 patients underwent surgery through minimally invasive approaches (MIAS group) whereas 765 patients underwent surgery through the conventional sternotomy (CONV group). Clinical outcomes were compared using a propensity score matching design. Results: Propensity score matching yielded 73 pairs of patients in which there were no significant differences in baseline profiles between the two groups. Patients in the MIAS group had longer aortic cross clamp than those in the CONV group ($74.9{\pm}27.9$ vs.. $66.2{\pm}27.3$, p=0.058). In the MIAS group, conversion to full sternotomy was needed in 2 patients (2.7%). There were no significant differences in the rates of low cardiac output syndrome (4 vs. 8, p=0.37), reoperation due to bleeding (7 vs. 6, p=0.77), wound infection (2 vs. 4, p=0.68), or requirements for dialysis (2 vs. 1, p=0.55) between the two groups. Postoperative pain was significantly less in the MIAS group than the conventional group (pain score, $3.79{\pm}1.67$ vs. $4.32{\pm}1.56$; p=0.04). Conclusion: Both minimally invasive approaches and conventional sternotomy had comparable early clinical outcomes in patients undergoing primary isolated aortic valve replacement. Minimally invasive approaches significantly decrease postoperative pain.

• Physical Therapy Rehabilitation Science
• /
• 제8권2호
• /
• pp.67-73
• /
• 2019

Objective: The purpose of this study was to compare the differences in the length of hospital stay between hemorrhage stroke survivors with health insurance and those with medical care after controlling all factors except for the type of medical insurance by using the propensity score matching (PSM) method. Design: Retrospective cohort study. Methods: Data from the Korean National Centers for Disease Control and Prevention's In-Depth Discharge Injury Survey between the years 2006 and 2012 were used for analysis. A total of 4,538 cases were defined as persons with hemorrhagic stroke (I60-I62) based on the block of categories in the International Classification of Diseases (10th). In order to analyze the inpatient period differences depending on the type of health care, which reflects one's socio-economic level, the chi-square and t-test was conducted. Results: Frequency and percentage were presented, and regression analysis was used to determine the factors affecting the inpatient period. Age, severity of disease, treatment outcome, and post-discharge status were no longer statistically significant after matching. The inpatient period of the persons receiving medical aid benefits was found to be significantly longer than those with national health insurance (p<0.05). Conclusions: The factors influencing the inpatient period of hemorrhagic stroke survivors were treatment outcomes, severity of disease, hospital admission process, and the type of health care. It is necessary for systematic and comprehensive governmental management for persons with hemorrhagic stroke to be transferred to long-term care facilities.