• Journal of the Korea Convergence Society
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• v.12 no.4
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• pp.267-274
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• 2021

This study used data from the 6rd and 12th year of the Korean Welfare Panel to evaluate the effects of the Personal Assistance Service(PAS) system on the labor market of PAS users' participation. For the purpose of this study, 64 program groups using the Korean PAS and 344 control groups not using the Korean PAS were selected using Caliper matching among the propensity score matching. A chi-square test was used for the difference in characteristics between groups, and a simple difference-in-differences (DID) model and a double-difference multiple regression analysis of DID were performed to estimate the effect of thepolicy before and after the Korean PAS. As a result of the study, it was found that statistically, PAS had no significant effect on the labor market. This is due to the low number of system users, resulting in low post-hoc power, incomplete matching and limited availability of PAS Assistants for Disabled People. Therefore, In order to demonstrate the effectiveness of the Personal Assistance Service(PAS) system, specialized services and systems that meet the needs of the disabled and household members should be implemented.

• The Korean journal of internal medicine
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• v.33 no.6
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• pp.1111-1118
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• 2018

Background/Aims: Chest pain is an essential symptom in the diagnosis of acute coronary syndrome (ACS). One-third of patients with ACS present atypically, which can influence their receiving timely lifesaving therapy. Methods: A total of 617 NSTEMI patients from the Korea Acute MI Registry (KAMIR) and the Korea Working Group on MI (KorMI) databases were analyzed. The study population was divided into two groups by symptoms at presentation (typical symptoms group, 128; atypical symptoms groups, 128). Results: In this study population, 23% of patients presented without chest pain. After propensity score matching, the contact-to-device time ($2,618{\pm}381minutes$ vs. $1,739{\pm}241minutes$, p = 0.050), the symptoms-to-balloon time ($3,426{\pm}389minutes$ vs. $2,366{\pm}255minutes$, p = 0.024), and the door-to-balloon time ($2,339{\pm}380minutes$ vs. $1,544{\pm}244minutes$, p = 0.002) were significantly higher in the patients with atypical symptoms than in those with typical symptoms, respectively. Atypical symptoms were an independent predictor for 1-year mortality (hazard ratio, 2.820; 95% confidence interval, 1.058 to 7.515; p = 0.038). The Kaplan-Meier estimates showed higher risk for 12-month mortality in patients with atypical symptoms (p = 0.048) and no significant difference for 12-month major adverse cardiac events (p = 0.487). Conclusions: Acute myocardial infarction patients with atypical symptoms were not rare in clinical practice and showed a high risk of delayed reperfusion therapy. After imbalance between the groups was minimized by use of propensity score matching, patients who presented atypically had a high mortality rate.

• Journal of Labour Economics
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• v.32 no.3
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• pp.61-89
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• 2009

This paper undertakes an international study on impacts of private education spending on student academic performance, using the OECD's PISA 2006 data. To circumvent endogeneity of the education spending, it relies on a propensity-score matching method. The empirical results suggest thai the effect of private education spending remains only modest for all the countries examined in the PISA 2006 data. A 10 percent increase in spending leads to no more than a 0.6 percent average improvement in test scores.

• Korean Journal of Radiology
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• v.23 no.6
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• pp.615-624
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• 2022

Objective: To compare the therapeutic outcomes of laparoscopic hepatic resection (LHR) and laparoscopic radiofrequency ablation (LRFA) for single subcapsular hepatocellular carcinoma (HCC). Materials and Methods: We screened 244 consecutive patients who had received either LHR or LRFA between January 2014 and December 2016. The feasibility of LRFA in patients who underwent LHR was retrospectively assessed by two interventional radiologists. Finally, 60 LRFA-feasible patients who had received LHR and 29 patients who had received LRFA as the first treatment for a solitary subcapsular HCC between 1 cm and 3 cm were finally included. We compared the therapeutic outcomes, including local tumor progression (LTP), recurrence-free survival (RFS), and overall survival (OS) between the two groups before and after propensity score (PS) matching. Multivariable Cox proportional hazard regression was also used to evaluate the difference in OS and RFS between the two groups for all 89 patients. Results: PS matching yielded 23 patients in each group. The cumulative LTP and OS rates were not significantly different between the LHR and LRFA groups after PS matching (p = 0.900 and 0.003, respectively). The 5-year LTP rates were 4.6% and 4.4%, respectively, and OS rates were 100% and 90.7%, respectively. The RFS rate was higher in LHR group without statistical significance (p = 0.070), with 5-year rates of 78.3% and 45.3%, respectively. OS was not significantly different between the LHR (reference) and LRFA groups in multivariable analyses, with a hazard ratio (HR) of 1.33 (95% confidence interval, 0.12-1.54) (p = 0.818). RFS was higher in LHR (reference) than in LRFA without statistical significance in multivariable analysis, with an HR of 2.01 (0.87-4.66) (p = 0.102). Conclusion: There was no significant difference in therapeutic outcomes between LHR and LRFA for single subcapsular HCCs measuring 1-3 cm. The difference in RFS should be further evaluated in a larger study.

• Proceedings of the Korean Society of Computer Information Conference
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• 2020.07a
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• pp.393-394
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• 2020

세 군 매칭을 수행하여 관찰 데이터를 구축하고 통계분석에 기반한 연구를 수행하는 경우가 종종 발생한다. 매칭작업은 각 군에 속한 개체의 성향점수를 서로 비교해 거리가 가까운 짝을 찾아야 하므로 카테시안 곱 만큼의 경우의 수를 따져야 하는 문제이고, 메모리 소요가 크다. 특히 세 군 매칭은 세 쌍의 거리가 가까운 triplet을 찾는 문제로, 세 개체 사이에 존재하는 세 개의 거리를 따져야 하기 때문에 메모리 소요가 두 군 매칭에 비해 훨씬 크다. 각 군에 속한 개체가 늘어나면 메모리소요가 기하 급수적으로 늘어나게 된다. R패키지에 포함된 TriMatch함수는 세 군 매칭 수행을 위해 가장 널리 사용되는 프로그램이다. 이 프로그램은 세 개체 사이의 세 개 거리가 가장 짧은 triplet을 찾는 방식으로 구현 되었다. 이 프로그램은 메모리 소요가 매우 커 각 군에 속한 개체의 수가 많아지면 메모리 부족 에러가 발생하는 경우가 많다. 본 연구에서는 세 군 매칭에 소요되는 메모리 소요를 줄일 수 있는 알고리즘을 제안하고자 한다. 이 알고리즘의 구현을 통해 각 군에 속한 개체가 늘어나도 안정적인 세 군 매칭 결과를 얻을 수 있을 것으로 기대한다.

• Journal of Gastric Cancer
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• v.20 no.4
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• pp.431-441
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• 2020

Purpose: Various studies have indicated that reduced-port robotic gastrectomies are safe and feasible for treating patients with early gastric cancer. However, there have not been any comparative studies conducted that have evaluated patients with clinically advanced gastric cancer. Therefore, we aimed to compare the perioperative outcomes of D2 lymph node dissections during reduced-port robotic distal subtotal gastrectomies (RRDGs) and conventional 5-port laparoscopic distal subtotal gastrectomies (CLDGs). Materials and Methods: We retrospectively evaluated 118 patients with clinically advanced gastric cancer who underwent minimally invasive distal subtotal gastrectomies with D2 lymph node dissections between February 2016 and November 2019. To evaluate the patient data, we performed a 1:1 propensity score matching (PSM) according to age, sex, body mass index, American Society of Anesthesiologists physical status classification score, and clinical T status. The short-term surgical outcomes were also compared between the two groups. Results: The PSM identified 40 pairs of patients who underwent RRDG or CLDG. The RRDG group experienced a significantly longer operation time than the CLDG group (P<0.001), although the RRDG group had significantly less estimated blood loss (P=0.034). The number of retrieved extraperigastric lymph nodes in the RRDG group was significantly higher than that of the CLDG group (P=0.008). The rate of postoperative complications was not significantly different between the two groups (P=0.115). Conclusions: D2 lymph node dissections can be safely performed during RRDGs and the perioperative outcomes appear to be comparable to those of conventional laparoscopic surgeries. Further studies are needed to compare long-term survival outcomes.

• Journal of Gastric Cancer
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• v.18 no.1
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• pp.58-68
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• 2018

Purpose: Generally, adjuvant chemotherapy (AC) should be initiated as soon as possible after surgery to eradicate microscopic cancer cells. In this study, we investigated the effect of early AC on the survival of stage II/III gastric cancer patients. Materials and Methods: Four hundred sixty patients who received AC (S-1 or XELOX) for pathologic stage II/III gastric cancer at Seoul National University Bundang Hospital between January 2008 and December 2014 were included. Patients were divided into 2 groups: early AC administration (within 4 weeks) and late AC administration (more than 4 weeks). Patients in the early AC group (n=174) were matched 1:1 with patients in the late AC group (n=174) by propensity scoring to adjust for clinical differences. Three-year relapse-free survival (RFS) was evaluated according to the timing of AC. Results: Three-year RFS was 98.1% in stage IIA (n=109), 85.0% in stage IIB (n=83), 87.4% in stage IIIA (n=96), 83.5% in stage IIIB (n=91), and 62.5% in stage IIIC (n=81). After propensity score matching, RFS was similar between early and late AC groups (hazard ratio [HR],1.04; 95% confidence interval [CI], 0.62-1.74; P=0.889). Pathologic stage and histological type were independent prognostic factors of RFS (HR, 2.05; 95% CI, 1.06-3.96; P=0.033 and HR, 2.61; 95% CI, 1.42-4.80; P=0.002, respectively). Conclusions: Early initiation of AC within 4 weeks does not affect survival rates in stage II/III gastric cancer.

• Health Policy and Management
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• v.30 no.3
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• pp.386-398
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• 2020

Background: We determined the differences in awareness of myocardial infarction and stroke according to the presence or absence of diabetes mellitus in the community. Methods: The 2018 Community Health Survey identified 20,812 people with diabetes mellitus aged 40-79 years. Using 1:1 matching by propensity score, 20,812 people without diabetes mellitus but with similar sociodemographic characteristics were selected as a comparison. Outcome variables were awareness of early symptoms of myocardial infarction and stroke and awareness of coping strategies in case of occurrence. Results: There was no significant difference between nondiabetic and diabetic people in terms of recognizing all early symptoms of myocardial infarction (nondiabetic, 42.7%; diabetic, 43.0%; p=0.43) and stroke (nondiabetic, 49.4%; diabetic, 49.4%; p=0.91). In addition, no significant difference was found between nondiabetic and diabetic people in the proportion of knowing correct emergency response to myocardial infarction (nondiabetic, 84.6%; diabetic, 84.4%; p=0.56) and stroke (nondiabetic, 81.3%; diabetic, 81.4%; p=0.77). Conclusion: Since people with diabetes are at greater risk of cardiovascular disease than the general public, it is important to lower the risk of disability and death by improving their awareness of early symptoms and correct emergency response to myocardial infarction and stroke.

• Journal of Gastric Cancer
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• v.18 no.2
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• pp.189-199
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• 2018

Purpose: This study sought to examine whether near total gastrectomy (nTG) confers a longterm nutritional benefit when compared with total gastrectomy (TG) for the treatment of gastric cancer. Materials and Methods: Patients who underwent nTG or TG for gastric cancer were included (n=570). Using the 1:2 matched propensity score, 25 patients from the nTG group and 50 patients from the TG group were compared retrospectively for oncologic outcomes, including long-term survival and nutritional status. Results: The length of the proximal resection margin, number of retrieved lymph nodes and tumor nodes, metastasis stage, short-term postoperative outcomes, and long-term survival were not significantly different between the groups. The body mass index values, and serum total protein and hemoglobin levels of the patients decreased significantly until postoperative 6 months, and then recovered slightly over time (P<0.05); however, there was no difference in the levels between the groups. The prognostic nutritional index values and serum albumin levels decreased significantly until postoperative 6 months and then recovered (P<0.05); the levels decreased more in the nTG group than in the TG group (P<0.05). The mean corpuscular volumes and serum transferrin levels increased significantly until postoperative 1 year and then recovered slightly over time (P<0.05); however, there was no difference between the groups. Serum vitamin $B_{12}$, iron, and ferritin levels of the patients did not change significantly over time, and no difference existed between the groups. Conclusions: A small remnant stomach after nTG conferred no significant nutritional benefits over TG.

• Journal of Gastric Cancer
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• v.16 no.4
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• pp.240-246
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• 2016

Purpose: It is hypothesized that robotic gastrectomy may surpass laparoscopic gastrectomy after the operators acquire long-term experience and skills in the manipulation of robotic arms. This study aimed to evaluate the long-term learning curve of robotic distal gastrectomy (RDG) for gastric cancer compared with laparoscopic distal gastrectomy (LDG). Materials and Methods: From October 2008 to December 2015, patients who underwent LDG (n=809) were matched to patients who underwent RDG (n=232) at a 1:1 ratio, by using a propensity score matching method after stratification for the operative year. The surgical outcomes, such as trends of operative time, blood loss, and complication rate, were compared between the two groups. Results: The RDG group showed a longer operative time (171.3 minutes vs. 147.6 minutes, P<0.001) but less estimated blood loss (77.6 ml vs. 116.6 ml, P<0.001). The complication rate and postoperative recovery did not differ between the two groups. The RDG group showed a longer operative time and similar estimated blood loss compared with the LDG group after 5 years of experience (operative time: 159.2 minutes vs. 136.0 minutes in 2015, P=0.003; estimated blood loss: 72.9 ml vs. 78.1 ml in 2015, P=0.793). Conclusions: In terms of short-term surgical outcomes, RDG may not surpass LDG after a long-term experience with the technique.