Accelerated failure time models for the analysis of competing risks

Choi, Sangbum,Cho, Hyunsoon Elsevier 2019 Journal of the Korean Statistical Society Vol.48 No.3

<P><B>Abstract</B></P> <P>Competing risks are common in clinical cancer research, as patients are subject to multiple potential failure outcomes, such as death from the cancer itself or from complications arising from the disease. In the analysis of competing risks, several regression methods are available for the evaluation of the relationship between covariates and cause-specific failures, many of which are based on Cox’s proportional hazards model. Although a great deal of research has been conducted on estimating competing risks, less attention has been devoted to linear regression modeling, which is often referred to as the accelerated failure time (AFT) model in survival literature. In this article, we address the use and interpretation of linear regression analysis with regard to the competing risks problem. We introduce two types of AFT modeling framework, where the influence of a covariate can be evaluated in relation to either a cause-specific hazard function, referred to as cause-specific AFT (CS-AFT) modeling in this study, or the cumulative incidence function of a particular failure type, referred to as crude-risk AFT (CR-AFT) modeling. Simulation studies illustrate that, as in hazard-based competing risks analysis, these two models can produce substantially different effects, depending on the relationship between the covariates and both the failure type of principal interest and competing failure types. We apply the AFT methods to data from non-Hodgkin lymphoma patients, where the dataset is characterized by two competing events, disease relapse and death without relapse, and non-proportionality. We demonstrate how the data can be analyzed and interpreted, using linear competing risks regression models.</P>

Omental Free-Shaped Flap Reinforcement on Anastomosis and Dissected Area (OFFROAD) Following Reconstruction after Gastrectomy: A Retrospective Case-Control Study

박경린,Won-Ho Han,Hyunsoon Cho,Junsun Ryu,김영우 대한내시경복강경외과학회 2020 Journal of Minimally Invasive Surgery Vol.23 No.1

Purpose: We devised omental free-shaped flap reinforcement on anastomosis and dissected area (OFFROAD) following reconstruction after gastrectomy. This study aimed to evaluate its safety and early clinical outcomes. Methods: One hundred fifty-six patients who underwent totally laparoscopic distal gastrectomy with delta anastomosis from July 2016 to April 2018 were divided into the OFFROAD group (80 patients) and non-OFFROAD group (76 patients). Differences in short-term operative outcomes and surgical complications were compared between the groups. All patients’ inflammatory marker levels were measured to monitor flap necrotic change and inflammatory reactions. The clinical features of both groups in terms of anastomotic leakage were transcribed. Results: The mean operation time of OFFROAD was five minutes shorter than non OFFROAD. Pain score in postoperative day1 and the serum WBC count on POD 1 was significantly lower in OG than in NOG. There were no statistical differences in short-term outcomes and surgical complications between two groups. Anastomotic leakage occurred in three patients in each group and there was no statistical difference in incidence. However, clinical features were notable when anastomotic leakage occurs. Unlike all three patients of non-OFFROAD group manifested every features of peritonitis, each patient of OFFROAD group just manifested only one of the three. Conclusion: This study showed the safety and feasibility of OFFROAD procedure. It might mitigate septic complications when there is an anastomotic leakage. Additional large-scale study is needed to assess the versatile usefulness of OFFROAD aside from its role as a physical barrier.

Nationwide Trends in the Incidence of Melanoma and Non-melanoma Skin Cancers from 1999 to 2014 in South Korea

Oh, Chang-Mo,Cho, Hyunsoon,Won, Young-Joo,Kong, Hyun-Joo,Roh, Yun Ho,Jeong, Ki-Heon,Jung, Kyu-Won Korean Cancer Association 2018 Cancer Research and Treatment Vol.50 No.3

<P><B>Purpose</B></P><P>This descriptive study was aimed to examine trends in the incidence of melanoma and nonmelanoma in South Korea.</P><P><B>Materials and Methods</B></P><P>The nationwide incidence data for melanoma and non-melanoma skin cancer was obtained from the Korea Central Cancer Registry. Age-standardized rates were calculated and analyzed, using a Joinpoint regression model.</P><P><B>Results</B></P><P>The incidence of basal cell carcinoma has increased dramatically both in men (average annual percentage change [AAPC], 8.0 [95% confidence interval (CI), 6.0 to 10.1]) and women (AAPC, 9.0 [95% CI, 7.5 to 10.4]). Squamous cell carcinoma has also steadily increased both in men (AAPC, 3.3 [95% CI, 2.6 to 4.0]) and women (AAPC, 6.8 [95% CI, 5.3 to 8.4]). Cutaneous melanoma increased continuously from 1999 to 2014 inwomen (AAPC, 3.5 [95% CI, 2.4 to 4.6]), whilst rapidly increasing in men until 2005 (APC, 7.9 [95% CI, 2.4 to 13.7]) after which no increase has been observed (APC, ‒0.2 [95% CI, ‒2.3 to 2.0]).</P><P><B>Conclusion</B></P><P>The incidence rates of melanoma and non-melanoma skin cancer have increased over the past years, with the exception of melanoma in men. Further studies are required to investigate the reasons for the increased incidence of these skin cancers in South Korea.</P>

산후 유방 마사지 손기술에 대한 다중사례분석

박현순,조인숙,김민경,Park, Hyunsoon,Cho, Insook,Kim, Min-Kyeong 한국여성건강간호학회 2017 여성건강간호학회지 Vol.23 No.3

Purpose: The aim of this study was to understand the hand-on breast massage techniques used by well-known experts in breastfeeding clinics. Methods: A qualitative multiple-case design was applied that involved a feasibility test. Four experts sampling qualitative data collected by observing participants and in individual interviews were analyzed by content analysis, linking data to the propositions, and cross-case pattern matching. This study explored differences within and between cases, and the possibilities of replicating findings across cases. Thirty-nine postpartum women participated voluntarily in the feasibility test, which investigated the usability of four massage techniques. Results: The four techniques showed considerable similarities in terms of the application of stimulation to the breast base and increased flexibility of the wired flexible body, which was the core mechanism underlying the techniques. The breast management strategies were consistent with existing practice guidelines with the exception of using cold cabbage to control engorgement pain. There was insufficient scientific evidence for supporting the massage techniques used by the experts. All of the techniques showed 100% education completeness, but application rates were higher for self-control-oriented techniques. Conclusion: The massage techniques applied by experts in breastfeeding were based on hypotheses and self-control techniques are feasible to apply in practice.

초·중등 현직교사의 학생 이해에 대한 인식 및 연수 요구도

최지연(Choi, Jiyeon),송현순(Song, Hyunsoon),권동택(Kwon, Dongtaik),조용선(Cho, Yongsun),이태석(Lee, Taeseok) 학습자중심교과교육학회 2013 학습자중심교과교육연구 Vol.13 No.1

이 연구는 교사들을 대상으로 학생 이해에 대해 어떻게 인식하고 있는지를 알아보는데 목적이 있다. 연구의 목적을 달성하기 위하여 학생 이해의 현황, 학생과의 소통, 학생 이해 관련 연수의 필요 및 요구도 등에 대해 질문지를 구안하였고 전국의 초ㆍ중등 현직 교사들을 대상으로 유층표집을 통해 온라인/오프라인 설문으로 총 445명의 자료를 확보하여 분석에 활용하였다. 이 연구의 결과는 다음과 같다. 첫째, 대부분의 교사들은 학생을 이해하고 있고 (9.8%) 학생 이해를 위해 노력 한다고(84.9%) 응답하였다. 둘째, 교사들은 가장 이해하기 어려운 학년으로 초등학교 6학년(59.2%), 중학교 2학년(66.7%), 고등학교 1학년 (57.6%)을 꼽았다. 셋째, 교사들은 학생 이해가 어려운 원인으로 교사 자신(37.1%) 을, 학생 이해의 방해 요인으로 업무 부담(56.1%)과 성장 경험(43.2%)을 가장 많이 선택하였다. 넷째, 학생에 대한 정보의 원천으로 교사들은 개인적 경험(62.6%)에 의존하고 있었다. 다섯째, 학생 이해를 위한 연수에 필요한 내용으로 초·중등교사들은 공통적으로 학생들 사이의 또래 문화 및 집단 심리, 정서적 교류 방법, 커뮤니케이션 역량 강화 프로그램을 가장 많이 선택하였다. The purpose of this study was to investigate teacher s perceptions and needs of student understanding in the field of education. A questionnaire designed to elicit teacher s perceptions and needs of student understanding that was consist of student understanding current status, communication with students, needs of student understanding education training program. It was given to 445 school teachers who were teaching at different sized district by nonproportional stratified sampling. The findings of this study are as follows: First, most of the teachers showed that they understand students(79.8%) and they try to understand students(84.9%). Second, most teachers replied that 6th grade of primary school, 2nd grade of middle school and 1st grade of high school students were most difficult to understand. Third, most of teachers showed that a cause of difficulty of student understanding was teachers themselves(37.1%) and factors of disturbance of student understanding were a load of business(56.1%) and experience of growth(43.2%). Fourth, most of teachers depend on private experience(62.6%) to understand student. Fifth, peer culture, group psychology, emotional exchanging method and communication competence strengthening program were commonly required in both primary school teachers and secondary school teachers for teacher training program of student understanding.

Second Primary Cancer Development in Patients with Hepatocellular Carcinoma in South Korea: A Nationwide, Population-Based Study, 2002-2013

( Hwa Young Choi ),( Joong-won Park ),( Hyunsoon Cho ),( Moran Ki ) 대한간학회 2017 춘·추계 학술대회 (KASL) Vol.2017 No.1

Aims: This study aimed to identify the epidemiologic characteristics for developing second primary cancer (SPC) among patients diagnosed as having hepatocellular carcinoma (HCC). Methods: This study used a large dataset derived from the National Health Insurance of South Korea from 2002 to 2013. The patients in this study were newly diagnosed with HCC between 2004 and 2006. We excluded the following patients: (i) those who had been treated for any other cancer before diagnosis of HCC; (ii) those who did not undergo CT, MRI, or liver biopsy within 180 days before HCC diagnosis; and (iii) those who were followed up within 180 days since HCC diagnosis. SPC cases were selected by using the ICD-10th; “C” or “D00-D09” or “D37-D48”, applying the criteria after 180 days of HCC diagnosis. Those with “ill-defined (C76-C80)” or “primary multiple sites (C97)” were excluded from the SPC cases. We calculated standardized incidence ratios (SIRs) and used competing risk regression with adjustment for death and consideration of initial treatment with transarterial chemoembolization, radiotherapy, liver transplantation, liver resection, and comorbidities, including diabetes, chronic obstructive pulmonary disease (COPD), chronic kidney disease, cerebral vascular disease, and ischemic heart disease. Results: We enrolled 24,036 HCC patients from 2004 to 2006, with a mean age of 56.7 years and mean follow-up duration of 4.92 years. Of the patients, 2,270 (9.4%) developed SPC after 180 days of HCC diagnosis. The age-SIRs for SPC among the HCC patients were higher than those for development of cancer among the general population in both men (SIR: 18.56) and women (SIR: 21.16) per 1,000 person-years. Older age (adjusted hazard ratio: 1.11 with a 10-year increase) was an independent risk factor for developing SPC in the HCC patients. However, COPD and diabetes were not independently associated with a risk of SPC. Conclusions: The incidence of SPC in the HCC patients was much higher than that in the general population, and the risk increased with age. Therefore, surveillance strategies could be formulated for HCC survivors, particularly in older patients.

Risk of Diabetes after Hepatitis B or C Infection in Korea, 2002-2013: A Population-Based Cohort Study

( Yeerae Kim ),( Hwa Young Choi ),( Hyunsoon Cho ),( Bo Hyun Kim ),( Moran Ki ) 대한간학회 2017 춘·추계 학술대회 (KASL) Vol.2017 No.1

Aims: While the association between hepatitis C virus infection and diabetes is established, the association between hepatitis B virus infection and diabetes is still unclear. We assess the association between hepatitis B and C virus infections and diabetes development using population-based cohort data. Methods: Data from the National Health Insurance Service―National Sample Cohort, which consists of 514,791 persons aged 40-79 years, representing approximately 10% of the Korean adult population, who had a health check-up between 2002 and 2003, were used. Adults with hepatitis B or C virus infection during 2002-2003, without a prior history of diabetes, were selected as subjects. Results: The cumulative incidences, incidence rates, and hazard ratios of diabetes were highest in the co-infection group, followed by those of hepatitis C, hepatitis B, and the non-infection groups. The cumulative incidence of 12 years was 43.5% in the co-infected, 30.4% in hepatitis C-, 22% in hepatitis B-, and 16.0% in the non-infected groups. The incidence rates per 1,000 person-years were 238.5, 221.9, 172.2, and 145.0 for the co-infected, hepatitis C virus-infected, hepatitis B virus -infected, and non-infected groups, respectively. The risk factor-adjusted hazard ratios for diabetes development were 1.90, 1.62, and 1.41 for the co-infected, hepatitis C virus infected, and hepatitis B virus infected groups, respectively. Conclusions: The study findings suggest that diabetes is associated with both hepatitis C and B virus infections. Thus, it is important to prevent, screen for, and treat hepatitis B and C virus infections to reduce the risk of diabetes.

Association between Family History of Hepatocellular Carcinoma (HCC) and Risk of HCC in Korea, a Hepatitis B Virus Endemic Area

( Sang Ho Lee ),( Joong-won Park ),( Kyung Eun Bae ),( Hyunsoon Cho ) 대한간학회 2017 춘·추계 학술대회 (KASL) Vol.2017 No.1

Aims: Familial predisposition as a risk factor for HCC has been reported worldwide. Especially, family clustering of HCC has been well-known in eastern Asian countries including Korea, a hepatitis B virus (HBV) endemic area. However, it is uncertain how much family history (FHx) of HCC increases HCC risk in Korea. We investigated the role of FHx of HCC on the risk of HCC in a single center cohort. Methods: We carried out cohort study in National Cancer Center, Korea, involving consecutive 733 patients who were diagnosed HCC and 121 confirmed benign tumor as controls between January 2014 and March 2017. All subjects filled out a questionnaire for FHx of HCC at the first visit to the clinic. Odds ratio (OR) and the corresponding 95% confidence interval (CI) of HCC for FHx of HCC were obtained from univariable logistic regression analysis. We also analized age, sex, smoking, alcohol drinking, diabetes mellitus(DM), hypertension(HTN), body mass index (BMI), HBV/HCV positivity, and presence of cirrhosis for HCC risk factors. Results: First-degree relatives (FDR; parent, sibling, child) of case subjects were more likely to have HCC (OR 4.135; 95% CI 1.978-8.647, p <0.001) than FDR of control subjects. Affected type and number of FDR with HCC were not statistically significant in HCC development. In subgroup analysis, HCC patients with FDR who had HCC presented HCC at earlier age than those who did not (mean 56.5 vs 59.5 years, p <0.001). Univariate analysis showed that men, heavy smoker, heavy drinker, DM, hypertension, HBV/hepatitis C virus (HCV) positivity and cirrhosis were also increased a risk of HCC. Conclusions: FDR FHx of HCC increased risk of HCC and was associated with earlier development of HCC in the Korean.

Association between Viral Hepatitis Infection and Parkinson’s Disease in Korea: A Population-Based Study, 2002-2013

( Hwa Young Choi ),( Mai Thi Ha ),( Kyung-ah Kim ),( Hyunsoon Cho ),( Moran Ki ) 대한간학회 2017 춘·추계 학술대회 (KASL) Vol.2017 No.1

Aims: This study aimed to clarify the association of chronic viral hepatitis with Parkinson’s disease (PD) and risk factors. Methods: Using National Health Insurance Service-National Sample Cohort data, we identified patients with chronic hepatitis B virus (HBV) or hepatitis C virus (HCV) infection (based on ICD-10 codes) with no history of PD or a history of secondary PD (G21) or Parkinsonism in diseases classified elsewhere (G22). To analyze PD risk factors, we calculated hazard ratios (HRs) separately using a Cox proportional hazards model adjusted for a 10-year age distribution, sex, and comorbidities including hyperlipidemia, hypertension, ischemic heart disease, epilepsy, diabetes, cirrhosis, stroke, and head injury, and a competing risk regression model additionally adjusted for death. Results: We enrolled 738,421 subjects from 2004 to 2007 (726,216 without chronic viral hepatitis, 9,776 with HBV, and 2,429 with HCV) and followed them through 2013 (mean follow-up duration, 9.3 years). The PD incidence per 1,000 person-years was 12.9, 8.9, and 41.6 for the subjects without chronic viral hepatitis and those with HBV and HCV, respectively. The 10-year cumulative incidence of PD was 2.45%, 0.93%, and 3.98% in persons without chronic viral hepatitis and in those with chronic HBV and HCV infection, respectively. HRs by Cox proportional hazard model were 0.80 (95% CI: 0.71-0.90) in HBV and 2.02 (1.83-2.23) in HCV. Older age, male sex, hypertension, ischemic heart disease, epilepsy, diabetes, stroke, and head injury increased the risk of developing PD. Using competing risk regression model, HRs were 0.76 (0.67-0.86) in HBV and 2.00 (1.82-2.18) in HCV, and risk factors of PD were identical except sex and head injury. Conclusions: The risk of PD was increased in persons with chronic HCV infection, but decreased in those with chronic HBV infection. Further studies are mandatory to elucidate the association of chronic viral hepatitis with PD.

Incidence and Overall Survival of Biliary Tract Cancers in South Korea from 2006 to 2015: Using the National Health Information Database

Byung-Woo Kim,Chang-Mo Oh,Hwa Young Choi,Joong-Won Park,Hyunsoon Cho,기모란 거트앤리버 소화기연관학회협의회 2019 Gut and Liver Vol.13 No.1

Background/Aims: There have been no nationwide studies to investigate the trends in incidence and 5-year survival rates of intra- and extrahepatic bile duct cancers and gallbladder cancer. Therefore, our study aimed to describe the incidence and 5-year survival rates of biliary tract cancers by subsites in South Korea. Methods: A total of 86,134 patients with biliary tract cancers were selected from the National Health Information Database. Age-standardized incidence rates and annual percentage changes were calculated. Lifetable methods and log-rank tests were used to determine the differences in survival rates. Cox-proportional hazard models were used to estimate the hazard ratio of the patients with biliary tract cancers. Results: The incidence rate of intrahepatic bile duct cancer decreased by 1.3% annually from 8.8 per 100,000 in 2006 to 7.8 per 100,000 in 2015. Extrahepatic bile duct cancer also showed a decreasing trend by 2.2% per year from 8.7 per 100,000 in 2006 to 6.7 per 100,000 in 2015. Gallbladder cancer showed the greatest decline, with an annual percentage change of 2.8% from 6.3 per 100,000 to 5.2 per 100,000 during the same period. The 5-year survival rates were 30.0% in gallbladder cancer, 27.8% in extrahepatic bile duct cancer, and 15.9% in intrahepatic bile duct cancer. Conclusions: The overall incidence rates of intrahepatic and extrahepatic bile duct cancer and gallbladder cancer decreased from 2006 to 2015. Among biliary tract cancers, intrahepatic bile duct cancers exhibited the highest incidence rate and the worst survival rate.