Social Epidemiology and Spatial Epidemiology: An Empirical Comparison of Perspectives

McDonald, Kelsey Nathel University of Minnesota 2013 해외박사(DDOD)

Social and spatial epidemiologists each bring a unique perspective to how they examine contextual or neighborhood-level determinants of health. Although both perspectives draw from epidemiology, social epidemiology is additionally grounded in sociology and causal counterfactual frameworks while spatial epidemiology is heavily influenced by medical geography and predictive models. No study to date has compared these two distinct perspectives, along with their corresponding analytical approaches and model results. Yet this comparison may advance contextual effects research in epidemiology by suggesting methodological enhancements, providing insights into the robustness of our conclusions to the perspective taken, and suggesting whether we can truly identify contextual effects from observational data. To facilitate this comparison we used both perspectives to examine a research question: What is the estimated effect of increasing neighborhood education or income on overweight/obesity, type 2 diabetes, and current smoking, independent of individual-level differences? The social epidemiology approach employed propensity score matching while the spatial approach used approximated spatial multilevel models. Data for this study came from the California Health Interview Survey (2005, 2007, 2009) and the American Community Survey (2006--2010). Results revealed minimal to no effect of neighborhood education and income on overweight/obesity, type 2 diabetes, or current smoking, but estimated effects did vary somewhat by approach. This comparison highlighted fundamentally different goals in social and spatial epidemiology: identifying causal factors to intervene compared to predicting potential causal factors to describe reality. Attempts to improve causal inference in observational studies by integrating analytical techniques across subfields will likely be hampered by different objectives and model requirements. This incompatibility for integration, lack of strong evidence of effects, and the overall identification problem cast further doubt on our ability to identify causal contextual effects using observational data. However, this work may help in the design of experiments, which is where we should now focus.

역학적 관점에서의 담배소송 고찰

이선영 연세대학교 보건대학원 2016 국내석사

1900년대, 흡연 관련 피해가 늘어나면서 담배의 위해성에 대한 연구들이 시작되고, 담배회사의 매개 역할이 드러나면서 담배소송이 시작되었다. 담배소송은 다른 일반 소송과 달리 흡연과 질병의 역학적 인과관계 증명이 중요한 쟁점 중 하나라는 점이 특징이다. 질병의 원인은 그 질병이 발생하는데 있어 중요한 역할을 하는 사건, 상황, 조건 또는 속성이거나 세 요인들의 한 조합이기도 하다. 인과성의 개념은 고대 그리스부터 시작되었으며, 20세기에 들어서 그 개념은 진화하고 그 의미가 조금씩 바뀌었다. 인과성을 판단하는 기준은 충분원인과 필요원인, 다중요인, 특정 기준 조건을 위한 필요성, 단일원인과 다중원인, 인과성과 상호작용에서의 요인들 등 여러 인과성 관련 이론들로 설명되어 왔다. 역학은 담배소송 이외의 소송에서도 활용되고 있는데, 의료소송, 업무 관련성 질환 소송, 환경소송, 제조물책임소송에서 각 소송의 성격, 소송 상황 및 사건 성격에 따라 인과관계 설명은 다양하며, 상이하게 활용되고 있다. 담배소송의 세계 현황에 대해 각국 담배소송을 역학적 관점에서 특징적인 판결을 중심으로 기술하였다. 특히, 한국의 과거 담배소송을 상세히 기술하였다. 한국 담배소송의 주요 판결에서, 폐암은 비특이성 질환이며, 흡연과 폐암 사이의 인과관계는 증명이 불가능하며, 역학적 상관관계는 개인에게 적용하기 어렵다고 판시했다. 역학적 연구 결과는 물질이나 원인 요인 노출이 해로운 영향을 가져왔는지 여부를 논하거나 규명할 수 있기 때문에 소송에서 개인의 인과관계를 밝히는 중요한 자료로 이용된다. 하지만, 담배와 질병 사이의 인과관계는 유해물질의 노출과 발병 사이에 상당한 시간이 경과했고, 유해물질을 비롯한 다른 원인 인자들이 복합적인 영향을 끼쳤을 가능성이 있기 때문에, 담배소송에서 역학적 증거를 증명하기란 쉽지 않다. 또한, 역학적 연구는 집단을 연구한 분야이므로 개별적인 개인에서의 인과를 입증하는데 부적절하다거나, 역학으로 과학적 증명이 불가능하다며 과학의 정당성에 의문을 갖고 있다. 또한, 폐암은 비특이성 질환이며, 모든 흡연자에게서 폐암이 발생하는 것이 아니며, 질병과 위험 노출 정도의 관련성을 결정짓는 기준이 모호하다는 등 역학에 대한 오래된 선입견 및 편견이 산재해 있다. 이런 역학에 대한 잘못된 인식에 반박하기 위해서는 역학의 본질에 대해 자세히 인지해야 한다. 역학이 담배소송에서 받아들여지기 위해서는 첫째, 법 관련 분야를 대상으로 역학을 포함한 폭넓은 교육 실시, 둘째, 과학적 원칙의 확실한 이해를 위해 원고 및 피고의 변론이 아닌 전담 전문가를 임명, 셋째, 법정에 적용된 과학적 근거에 대하여 피드백을 제공할 필요가 있다. 담배소송에서 역학의 본질과 개념을 올바르게 이해하고, 역학적 연구를 증거로 채택하여 흡연과 질병과의 인과관계를 인정한 소송은 매우 드문 경우였다. 그러나, 최근 몇몇 소송에서 역학적 근거를 인정한 소송 사례를 접할 수 있다. 역학에 대한 올바른 이해를 기반으로, 담배소송에서 역학이 더 이상 논란의 대상이 되지 않고 국민건강증진에 기여할 수 있는 과학적 근거가 되기를 기대한다. 이러한 역학에 대한 인식의 전환은 전세계 공중보건의 패러다임을 변화시킬 것이다. Since the 20th century, no sooner the result of cigarette sales surged than a primary lung cancer has been increased. It was believed the lung cancer was caused by cigarette so that epidemiological studies of the causations between smoking and lung cancer has been flooded afterward. Also, tobacco litigations have been started as the consequence for smoking. However, causation in tobacco litigation is highly complex to be approved and determined in the courtroom due to a number of reasons. In epidemiology, causation is an event, a condition, a characteristic or a combination of these three when a disease occurs. Causation plays a major role in the courtroom and sometime it is even difficult to be proved or implemented. The concept of causation has been slightly changed from Aristoteles in the ancient Greek to the Surgeon General’s Report and the Bradford Hill’s considerations. Causation can be distinguished by sufficient cause and necessary cause. To decide a causation between factors should be considered as multiple factors, the need for a specific reference condition, single or multiple causes and factors in causation and interaction. Epidemiology can be applied in different types of litigation such as medical malpractice litigation, work related disease litigation, environmental litigation or product liability litigation. Each litigation has own specific feature of applying epidemiology but the intrinsic value of epidemiology in each litigation is identical. Tobacco litigation started from various countries. Each country’s tobacco litigation varies in their own policy, politics, culture or environment as well as the way how epidemiology in tobacco litigation is employed as a scientific evidence. There is a number of tobacco litigations which the causation between cigarette and disease has been approved or disapproved depending on cases. Because epidemiology studies determine whether an exposure leads to a harmful effect or not, epidemiology studies can be accepted in the tobacco litigation. Nevertheless, bringing the epidemiology evidence in the courtroom is exceptionally controversial due to the core principle of epidemiology. There are misconceptions in epidemiology such as epidemiology studies focus on a population group so the studies cannot represent an individual’s effect, epidemiology is not suitable as a scientific evidence, the lung cancer is so-called ‘non-specific disease’ or there are non-smokers among the lung cancer patients and how much exposure to smoking the judge can decide whether it is a strong association between smoking and the health outcome. With all these misunderstandings, we should try to understand the true nature of epidemiology and try to get the best outcome with epidemiology in litigation. As a scientific evidence in epidemiology applied to the tobacco litigation courtroom has been accepted recently, which is a great improvement highlighted in the tobacco litigation history. Such an improvement of epidemiology in the courtroom is one of ways to remedy the underprivileged and it must practice the realisation of social justice. The substantial amount of epidemiological studies about the risk of tobacco have been introduced in the courtroom. If tobacco jeopardises people’s health then everyone should put an effort on preventing any tobacco related diseases and maintaining well-being life. The ministry of health in Korea also has been publishing TV and public ads to announce the risk of tobacco. The TV and public ads contain graphic images which make smokers feel uneasy about smoking. Moreover, with cigarette related policies and controls like the double up cigarette cost enforced, the Korean government tries to initiate the public health reform. In this little move of the government, the awareness of the risk of smoking will spread to the public gradually. Little awareness gets bigger and bigger like a snowball so that the fine attitude toward to epidemiology should be scattered all over the world. Therefore, epidemiology will not a controversial issue in the courtroom any further and epidemiology is the absolute only one scientific evidence which can improve people’s health. For sure, this epidemiology can change the wave of the world public health.

The Effect of Non-pharmacological Interventions for Smoking Cessation : Mathematical Modeling Approach

정재헌 부산대학교 대학원 2021 국내박사

중독의 카테고리중 하나인 흡연은 사회문제의 일부이다. 특히나 흡연을 한 사람들은 여러가지 방법을 통해 금연을 하기 위해 노력을 하지만 흡연을 바로 그만두기가 어려운 실정이다. 그래서 우리는 금연을 위해서 흡연현상을 나타내는 두 가지 측면의 수리모델을 구성한다: 역학과 진화론적 게임이론 접근. 첫번째, 우리는 역학을 기반으로 금연을 위해 전자담배 사용의 효과를 연구한다. 기존의 담배모델을 개선하여 전자담배가 포함된 형태의 수리모델을 구축한다. 우리는 실제 데이터 기반으로 최소자승법을 이용하여 모델의 파라미터들을 추정한다. 그리고 우리는 재생산 지수와 평형해를 구하고 안정성을 조사한다. 또한 재생산 지수가 증가함에 따라 smoking free equilibrium 과 smoking present equilibrium 사이에서 안정성의 변화가 생기는 분기 분석을 조사한다. R0 에 영향을 미치는 파라메터를 조사하기위해 민감도 분석을 시행하였다. 역학측면의 결과로써, 전자담배는 흡연을 줄이는데엔 효과가 있지만 완벽히 금연을 시키지 못하였다. 그리고 흡연자들은 담배보다 전자담배에 중독될 가능성을 간과해선 안된다. 역학적인 관점은 흡연자와 비흡연자 사이의 동태만 확인 할 수 있기에, 우리는 더 세부적으로 흡연을 선택하게 되는 이유에 대해연구한다. 두 번째, 우리는 사람들이 흡연을 선택하는 과정을 분석하기 위해 누적 전망 이론과 진화론적 게임 이론을 사용하여 수리모델을 구성한다. 누적 전망 이론은 불확실한 상황에서 사람들이 의사결정을 어떻게 내리는지에 대한 이론이고, 진화론적 게임 이론은 상대방과게임 시 보수가 높은 쪽으로 전략을 선택하여 전략변화의 역학에 초점을 맞춘다. 두 이론흡연을 적용하여, 흡연자와 비흡연자가 흡연에 대한 선호도와 가중치를 포함해서 흡연의 가치를 판단한다. 그리고 두 플레이어가 게임을 할 때 서로의 전략에 따라 전략선택이 어떻게 이루어지는지 시나리오 별로 조사한다. 진화게임이론측면의 결과로써, 흡연자의 흡연전략 선택과 흡연을 할 수 있는 상황일때, 흡연자와 비흡연자 모두에게 흡연전략선택에 민감하게 작용한다. 이후에 후속연구를 위해, 역학과 진화게임이론 관점을 통합하는 새로운 프레임워크를 구축한다. COVID-19 을 적용하는 예제로써, 스웨덴과 한국의 예방정책을 비교했을 때, 지역 커뮤니티에서 COVID-19 발생 시 선제대응 행동전략으로부터 개인과 그룹간의 전략선택의 효과를 평가한다. 사람들로부터 선제대응과 비선제대응 전략을 기반으로 게임을 구성하고, 보수, 내쉬 평형해 그리고 그룹최적해를 조사하였다. 그리고 진화게임이론으로부터 얻어진 평형해를 이용하여 역학모델과 통합하여 감염확률과 재생산지수를 얻었다. 결과적으로 선제대응은 COVID-19 의 감염전파에 대응하는 적절한 예방 수단이다. 우리는 중독프로세스를 구축하기위해 역학과 진화게임이론을 통합하는 새로운 프레임워크를 고안하였다. 이 프레임워크는 중독 프로세스를 더욱 잘 표현하하고, 나아가 심리학자, 흡연연구자들에게 유용하게 될지 모른다. Smoking, one of the categories of addiction, is part of a social problem. In particular, people who have smoked try to quit smoking through various methods, but it is difficult to quit smoking immediately. Then we construct a two-aspect mathematical model representing smoking phenomena for smoking cessation: epidemiology and evolutionary game theory approach. First, we study the effects of using electronic-cigarettes (e-cigarettes) for smoking cessation based on epidemiology. The established cigarette model is improved to build a modified model that includes e-cigarettes. We estimated the parameters of the model using the least square method based on real data. And we find the basic reproduction number (R0), equilibria, and investigate the stability. In addition, we investigated a bifurcation analysis of the exchange in stability between smoking free equilibrium and smoking present equilibrium as the basic reproduction number increases. A sensitivity analysis was performed to investigate the parameters affecting R0. As a result of the epidemiological aspect, e-cigarettes are effective in reducing smoking, but they can not completely quit smoking. And smokers should not be overlooked the possibility of being addicted to e-cigarettes rather than cigarettes. Since the epidemiological point of view can only identify the dynamics between smokers and non-smokers, we conducted the reasons for choosing smoking in more detail. Second, we construct a mathematical model using the cumulative prospect theory and evolutionary game theory to analyze the process of people choosing smoking. The cumulative prospect theory is a theory about how people make decisions in uncertain situations, and evolutionary game theory focuses on the dynamics of strategy change by choosing strategies with higher payoffs when comparing strategies with opponents. Applying smoking to both theories, smokers and non-smokers judge the value of smoking, including preferences and weights for smoking. And, when two players play the game, we investigate how the strategy selection is made according to each other’s strategies by scenario. As a result of evolutionary game theory, when smokers can choose a smoking strategy and in situations where they can smoke, both smokers and non-smokers are sensitive to smoking strategy choices. For further research later, we has built a new framework that integrates the epidemiology and evolutionary game theory. As an example of applying COVID-19, when comparing the prevention policies of Sweden and South Korea, we evaluated the effectiveness of strategic choices between individuals and groups from pre-response action strategies when COVID-19 emerges in local communities. The game was constructed based on pre-response and non-pre-response action strategies from the population, and payoffs, Nash equilibrium, and group optimum solutions were investigated. And by using the equilibrium obtained from the evolutionary game theory, it was integrated with the dynamic model to obtain the probability of infection and basic reproduction number. As a result, pre-response action strategy is an appropriate preventive measure against the transmission of COVID-19. We devised a new framework integrating epidemiology and evolutionary game theory to build the addiction process. This framework may better represent the addiction process and, furthermore, be useful to psychologists and smoking researchers.

A Comprehensive Study on African Swine Fever (ASF): Epidemiology, Climate Change Impact and Control Measures

TIWARI SHRADDHA 강원대학교 대학원 2023 국내박사

Veterinary epidemiology is the science of studying patterns of health and viruses in different groups and populations and the fundamental of veterinary medicine for preventing the spread of animal diseases to humans as well as the prevention, control, diagnosis, and treatment of diseases impacting the health of domestic and wild animals. This essay explores the epidemiological dynamics of African swine Fever (ASF). The ASF Virus (ASFV) is a large and complex DNA virus that directly harms the pig family. The ASFV genome is circular and approximately 170-194 kb in size, encoding over 170 different genes. African Swine Fever (ASF) is a highly contagious and often deadly disease affecting domestic and wild pigs. It was first reported in Africa in the 1920s and has since spread to many countries in Europe, Asia, and the Americas. The main mode of transmission of ASF is through direct contact between infected and healthy pigs or through indirect contact via contaminated feed, clothing, vehicles, or other fomites. The virus can also persist in the environment for long periods of time, making it difficult to control its spread. The impact of ASF on the pork industry can be significant, as outbreaks result in large-scale culling of infected pigs and the imposition of trade restrictions, leading to market instability and economic losses. Efforts to control the spread of ASF include measures such as vaccination, improved biosecurity, and strict control of pig movements. However, a vaccine is not yet commercially available, and the disease remains a significant threat to the global pork industry. Pathologically, ASFV infection results in a range of symptoms, including fever, lethargy, anorexia, and haemorrhagic lesions in various tissues, including the skin, spleen, liver, and lymph nodes. In severe cases, the virus can cause multi-organ failure and death, often within a matter of days. The pathological expression of ASFV is determined by the interaction between the virus and the host and by the genetic variation among ASFV strains. The severe and often deadly outcome of ASFV infection highlights the need for continued research into the virus and its interactions with the host, with the ultimate goal of developing effective strategies for controlling the spread of ASF. To assist the control management, this study focuses on producing informative data on ASF epidemiology. This study conducted a comprehensive examination of the African swine fever (ASF) issue using various methods. Firstly, bibliometric analysis for scientific content about ASF using Web of Science database. Secondly, Climate change is current global issues, the impact of climate change on the future spread of ASF was analyzed using WorldClim bioclimatic variables and Representative Concentrative Pathways (RCP) 2.6, 4.5, 6.0, and 8.5 for current, 2050, and 2070, with the presence data of global ASF outbreaks in wild boar locations between 1st January 2019 to 29th July 2022 and the maximum entropy (Maxent) model. A quantitative risk analysis was performed by introducing the global reproduction rate of the disease using the doubling time approach and global ASF outbreak data in wild boar from the Empres-i data portal. The study also investigated the spatial growth of ASF in South Korea as an example case, using the minimum convex polygon (MCP) approach for quarantine measures and finally, a mental model was developed using a system dynamic approach based on literatures and our knowledge to understand the causal relationships involved in the spread of ASF. From bibliometric study, we found that increasing the outbreak of ASF, researchers are working to develop new methods for controlling and preventing the spread of ASF, including developing vaccines, improving biosecurity measures, and minimizing its impact on the pork industry and global food supply and high indexed publications are also increasing. Based on the Web of science categories, it was noticed that most of ASF-related research were on Veterinary Sciences followed by Virology and Infectious disease. China followed by USA, Spain and England were the highly dominated countries contributing Web of Science (WoS) indexed research. Elsevier followed by MDPI, Wiley and Springer Nature were major publishers of ASF-related papers. ‘African swine fever’, ‘African swine fever virus’, ‘domestic pigs’, ‘epidemiology’ and ‘pigs’ were the highly adopted keywords in the previous research and different dominated keywords were identified in each cluster of bibliometric keyword network. We also found climate change is contributing to the spread of ASFV. Among the bioclimatic variables, the driest month (Bio14) and annual mean temperature (Bio1) are major influencing factors. Based on the bioclimatic variables and RCP scenarios, future climate is identified favorable to ASF spread. Based on the global scenario, ASFV spread in wild boar above the threshold line (R0≥1). The recent growth trend (R0=5.87 @ infectious period 3.5 days) flagging the very high risk to wild boar and pig farm. Strict biosecurity measures, movement control, monitoring of pigs, widespread culling of infected pigs, quarantine measures, and OIE protocol are recommended. ASF has spread rapidly from Africa to several other continents, including Europe, Asia, and Americas. Based on the 37, 778 outbreaks reported in Empres-i, the highest record were identified in Poland (30.21 %) followed by Romania (19.11 %) and Latvia (10.16%). In South Korea, the ASF was observed increasing with linear rate 2.36 per day (R2:0.98) examined form the outbreaks in wild boar data recorded between September 17th, 2019, to May 20th, 2022. The weekly and monthly spatial growth through MCP was found to increase with logistic growth rates 0.022 km2 per week and 0.094 km2 per month, respectively. A mental model on spreading of ASF has been developed. A total of twenty-three variables were used to visualize the dynamics of disease spread and active veterinary services with awareness program and R&D support were highlighted as major variables to control the spread. The model will help to understand how changes in one part of the system can affect other parts and identify potential leverage points for intervention or improvement. The current study about the spatial growth of African Swine Fever (ASF) and the related literature have important implications for controlling the spread of the disease. Effective control of ASF is essential for maintaining the health and welfare of wild/domestic pigs, ensuring the availability of pork products, and avoiding economic losses due to disease outbreaks. Understanding the patterns of ASF spread is crucial for developing effective control measures, such as implementing biosecurity protocols, establishing surveillance systems, and restricting disease vectors such as boar, pig and tick movements. The study of ASF spatial growth can also help identify high-risk areas for disease outbreaks and inform targeted interventions. Furthermore, literature on ASF can provide insight into the molecular mechanisms underlying the disease, the epidemiology of ASFV, and the development of effective vaccines and treatments. This knowledge is crucial for advancing our understanding of the virus and developing strategies to control its spread. This study has significant implications for the global pork industry, as well as for public health and food security.

Incidence, Severity, and Biomechanics of Head Injury in Taekwondo

파이프 가브리엘 연세대학교 대학원 2015 국내박사

Context: One area within taekwondo epidemiology that has not been thoroughly addressed are time-loss injuries. Additionally, as incidence of head injury in taekwondo is high, only a few investigations have studied the underlying mechanisms for these injuries from a biomechanical perspective. Most recently only one component of head injury (linear acceleration and head injury criterion) have been reported in taekwondo. As a result of these recent biomechanical studies, one group has provided an assessment of selected protective headgear impact attenuation properties using a novel pendulum impactor apparatus. Objectives: This proposed project is focused on reporting time-loss injuries at taekwondo competitions along with a biomechanical investigation into the head injuries, highlighting the linear and rotational accelerations occurring at the head of an anthropometric crash test dummy. Third objective is to assess the performance of protective headgear and footpads. Design: prospective observational epidemiology study Setting: taekwondo competition venues and a biomechanics laboratory. Patients and or other participants: Intervention: Epidemiology: total of 187 athletes (152 males age = 28.8 + 5.7, height = 175.2 + 8.7cm, weight = 68.7 + 12.7 kg) 35 females (age = 28.6 + 6.6, height = 163.3 + 4.1cm, weight = 52.6 + 2.6 kg). Head kicking study: male participants (n= 11, 175 + 5.3 cm, 71 + 8.3 kg) with 7.5 + 3.6 years of taekwondo training volunteered for this study. Main Outcome Measures: Results: Epidemiology: The overall injury incidence was 63.7 per 1000 A-E (95% CI: 35.1 to 92.4) and 31.0 per 1000 M-E (95% CI: 17.1 to 45.0). Contusions were the predominant injury type (26.8 , 95 % CI = 8.2 to 45.4: 13.1 injuries per 1000 M-E, 95 % CI = 4.0 to 22.1). The total concussion incidence was 6.7 per 1000 A-E (95% CI: -2.5 to 16.0) and 3.2 per 1000 M-E (95% CI: -1.3 to 7.8). Head kicking mechanics: A statistically significant difference was observed ??????????in RLA (p = 0.00075, η2 = 0.04, 95% CI: -0.94 to 1.03). No differences were identified with ROTA (p = 0.734, η2 = 0.0004, 95% CI: -0.98 to 0.98). A statistically significant difference (p < 0.001) between kicks in HIC was observed, with a medium effect (η2 = 0.08, 95% CI: -0.98 to 1.07). Tukey HSD test identified differences (p < 0.001) between kicking techniques in RLA and HIC. Protective equipment testing: Impacts from two conditions (no headgear + footpad, no headgear + no footpad) exceeded the 500 g maximum range for the ti-axial linear accelerometer. Large differences in RLA were found between padding conditions (p = 0.41, eta2 = 0.17, 95% CI: -0.81 to 1.2) and ROTA (p = 0.31, eta2 = 0.25, 95% CI: -0.74 to 1.2) however the the magnitude of these differences are unclear in reference to the confidence intervals of the effect sizes. Turkey HSD test did not identify significant differences for both RLA (p = 0.41) and ROTA (p = 0.31). Conclusions: Epidemiology: The incidence of severe injury is surprising and careful attention should be brought towards improving the immediate care of these injuries as well as considering options to implement the use of customized protective equipment to prevent upper limb injuries as an injury to an already debilitated limb (congenital or acquired) may put undue hardship to these athletes who already face challenges. Head kicking mechanics: These data are important as impact measures from this study may be more representative of impact levels experienced by the vast majority of taekwondo practitioners worldwide, whereas most studies recruited elite athletes (a small percentage of the actual body of competitors worldwide). Although the clench axe kick elicited a lower RLA, the ROTA of this technique was higher than levels from other techniques (although not large differences in reference to effect sizes). Protective equipment testing: As peak linear head accelerations (>500 g) of the instrumented head-form, when impacted with only a protective footpad, exceeded the passing criteria (<150 g) the ??results of this study do not support the removal of protective taekwondo headgear like in boxing. Because rotational accelerations exceeded levels recently attributed diagnosed concussion, manufactures may consider materials aimed at reducing rotational accelerations that occur due to head kicks.

Opening the black box: A reassessment of mediation from a counterfactual perspective

Hafeman, Danella Columbia University 2008 해외박사(DDOD)

The aim of this dissertation is to reframe the way that we think about mediation in epidemiology. In other social sciences, the concepts and methods regarding mediation analysis are well developed and used extensively. In contrast, a conceptual framework for the assessment of mediation is lacking in epidemiology. While epidemiologists frequently consider mediation when formulating research questions, the methodological support for assessing mediation is severely limited. In fact, most of the methodological literature about mediation focuses on the biases that might invalidate this analysis. In particular, investigators have described the biases that might arise in the presence of (1) interaction between the exposure and mediator and (2) confounding of the mediator-disease relationship. Based on these critiques, some authors have discouraged the assessment of mediation altogether. To counteract this rather gloomy view of mediation analysis, we take the following two-pronged approach. First, we provide a conceptual framework for the assessment of mediation in epidemiology. In particular, we describe reasons that an epidemiologist might want to assess mediation, and link these reasons to previously defined mediational effects. We also review the standard methods of mediation analysis used in epidemiology, and determine the extent to which quantities obtained from standard methods reflect mediational effects of interest. Second, we reassess the impact of potential biases on our estimates of mediation. Specifically, we derive assumptions necessary for the unbiased estimation of mediational quantities. This derivation allows us to compare the assumptions across various mediational effects to determine if some effects are more vulnerable to the effects of bias than others. As described in the text, such a comparison sheds light on whether or not the assumption of "no interaction" between the exposure and mediator is necessary, or even helpful. In addition, we develop a sensitivity analysis program to assess the degree to which confounding of the mediator-disease relationship might bias results. Using this program, we reassess results from two well-known mediation examples, to determine the degree to which confounding might have biased these results. We find that the situation is generally not as dismal as previous investigators have claimed. First, the standard methods for the assessment of mediation, while they do not generally equal mediational quantities of interest, represent a weighted average of these quantities. In addition, these measures can easily be modified to perfectly correspond to our concepts of mediation. Second, the assumptions derived for the unbiased assessment of mediation are, at least in some cases, less stringent than those previously proposed. Third, the assumption that there is "no interaction" between exposure and mediator is not generally necessary, although it might be helpful in some cases. Fourth, as previously shown, confounding of the mediator will bias the estimate of mediational quantities. However, the potential impact varies tremendously based on observed results; in certain cases, confounding of the mediator does not represent a plausible alternative explanation for the observed results. In general, we find that the assessment of mediation is less vulnerable to potential biases than previous work has indicated. This is particularly true if we are concerned with the correct qualitative identification of direct and indirect effects, rather than the valid quantification of these effects. However, as with any observational analysis, alternative explanations for an observed indirect effect should be considered. To this end, the sensitivity analysis developed in this dissertation might be used by future investigators to determine the amount of confounding necessary to explain observed results.

Spatial measurement error methods in air pollution epidemiology

Bergen, Silas University of Washington 2014 해외박사(DDOD)

Air pollution epidemiology cohort studies often implement a two-stage approach to estimating associations of continuous health outcomes with one or more exposures. An inherent problem in these studies is that the exposures of interest are usually unobserved. Instead observations are available at misaligned monitoring locations. The first stage entails building exposure models with the monitoring data and predicting at subject locations; the second stage uses the predictions to estimate health effects. This induces measurement error that can induce bias and affect the standard error of resulting estimates. Berkson-like error arises from smoothing the exposure surface, while classical-like error comes from estimating the exposure model parameters. Accurately characterizing and correcting for both types of measurement error depends on assumptions made about the spatial surface and exposure model used to derive predictions. This dissertation addresses spatial measurement error in air pollution epidemiology. We first describe and apply parametric measurement error methodology when assuming the exposure surface is a stochastic Gaussian process. We extend these parametric approaches by deriving P-SIMEX, which yields more flexible bias correction. We then motivate a semi-parametric framework wherein the exposure surface is viewed as fixed and modeled with penalized regression splines. We discuss the resulting measurement error, describe how the exposure model penalty regulates measurement error, and derive an analytic bias correction. Finally we extend the semi-parametric methodology to the multi-pollutant setting. We show the direction of the biases are unpredictable, and the magnitude of the biases are much larger than those in single-pollutant studies. We derive a multi-pollutant bias correction that can be combined with a simple non-parametric bootstrap to achieve accurate 95% confidence interval coverage. Throughout we apply our methods to analyzing associations of continuous health outcomes with predicted exposures in the Multi-Ethnic Study of Atherosclerosis and the Sister Study of the National Institute of Environmental Health Sciences.

The Prediction and Prevention of Suicidal Behavior: The Intersection of Developmental Psychopathology and Translational Epidemiology

O'Reilly, Lauren Marie Indiana University ProQuest Dissertations & Theses 2023 해외박사(DDOD)

Suicide is a major public health concern. Over the past twenty years in the United States, the suicide rates increased by over 30% in half of the states and increased in all but one state. Among adolescents, suicide is the second leading cause of death. Suicidality research is inherently difficult to conduct given statistical issues related to the low base of suicide, poor communication across the field due to a lack of standard terminology, the heterogeneity in identified risk factors, and the exclusion of individuals with suicidal behavior in prospective data collection. These issues heighten the critical need for creative approaches in suicidality research. This dissertation integrates two frameworks-developmental psychopathology and translational epidemiology-in order to conceptualize developmental processes of suicidality and use epidemiological methodological approaches. Understanding suicidality from a developmental psychopathology lens reinforces key principles that can guide suicidality research, including studying suicidality across multiple levels of analysis, developmental periods, and specific sensitive periods. The use of epidemiological data and methods are particularly advantageous when researchers are constrained, whether ethically or logistically, to collect data directly with individuals experiencing suicidality. Advanced epidemiological methods combined with large-scale datasets offer the opportunity to test causal inferences. The dissertation comprises three chapters that are situated at the intersection between developmental psychopathology and translational epidemiology approaches. Chapter 1 examined the association between sexual orientation and suicide attempt and self-harm in an adolescent, twin sample. Chapter 2 examined the association between the Affordable Care Act young adult mandate, which expanded health insurance coverage, and suicide attempt and suicide. Chapter 3 applied machine learning algorithms to predict suicide attempt and suicide after specialist mental health care treatment among adolescents in Stockholm County, Sweden.

Epidemiological study of Taekwondo injuries : 1-year prospective study

손보애 Graduate School, Yonsei University 2017 국내석사

2008년 베이징 올림픽 참가 종목 중 태권도의 부상률은 두 번째로 높았으며, 2012년 런던 올림픽에서는 부상률 가장 높았다. 이처럼 태권도의 부상률이 높고, 태권도 인구는 세계적으로 한국에 가장 많음에도 불구하고 선수 부상을 예방하기 위한 부상감시시스템에 관한 연구 없다. 대회 중 태권도 부상 역학 연구가 많음에도 불구하고, 같은 대상자를 전향적으로 추적하는 연구 또한 부족하다. 지난 10년간, 태권도 공식경기에서, 규칙 변화와 새로운 기술은 매우 중요하다. 하지만 2014년 이후에 태권도 역학 연구는 없다. 따라서 이 연구의 첫 번째 목적은 태권도 역학을 기술하는 것이다. 두 번째 목적은 1년간 추적한 부상 발생, 부상 부위, 유형, 동작, 기전, 부상으로 인한 시간 손실이 나이, 성별, 연습, 게임에 따른 차이점을 알기 위한 것이다. 세 번째 목적은 나이, 성별 그룹에 따라 1년 추적과 단일 대회 간의 부상 발생률을 차이점을 알기 위한 것이다. 네 번째 목적은 부상의 위험 요소가 무엇인지 확인하는 것이다. 연구대상은 대한태권도협회에 정식으로 선수 등록된 285명 중·고등학교 및 대학교 선수들을 대상으로 부상감시시스템을 실시하였다. 성별과 연령의 차이를 비교하기 위해 카이 제곱 검정을 사용했습니다. 부상 발생률과 부상 노출, rate ratio (RR)와 교차비 및 95 % 신뢰구간 (CI)을 계산하였다. 1년간 총 336건의 부상이 보고되었다. 연습 중 235건의 부상과 49,018 부상 노출이 발생하였고, 총 1000번 부상 노출 당 부상이 4.79건이 발생하였다. 경기 중에는 83건의 부상과 3,595 부상 노출이 발생하였고, 1,000번 부상 노출 당 23.09건이 보고되었다. 성별 간에 부상 비율은 통계적으로 차이가 없었다. 청소년 선수는 성인 선수에 비해 높은 부상 발생률(교차비: 1.86, 95% 신뢰구간: 1.18-2.95)을 보였다. 또한, 청소년 부상자의 부상 발생률은 단일대회에서도 성인보다 높았다(RR: 2.90, 95 % CI: 2.74 ~ 3.07). 그러나 성인 선수는 부상으로 인한 시간 손실이 2.86배 더 높았다(교차비: 2.86, 95% 신뢰구간: 1.66-4.79). 부상 위치는 대부분 하지(79.3 %)에서 발생하였다. 특히 발과 발목은 다른 신체 부위보다 높았으며 부상 유형은 염좌가 가장 많았다(25.7 %). 대부분의 부상 동작은 발차기 (63.7 %)이었다. 가장 일반적인 기전은 ‘서로 부딪혀서’(51.5 %)였다. 본 연구 결과는 청소년 선수가 부상률이 연습과 경기 중에서 성인 선수보다 더 높다는 것을 제안한다. 하지만, 성인 선수의 부상으로 인한 시간 손실은 더 높았다. 여자 선수는 연습 중에 남자 선수보다 더 많은 부상을 경험했다. 향후 연구는 이 차이점에 대해 조사 되어야할 것이다. 지속적인 부상감시시스템은 태권도 선수가 입는 부상의 심각성과 빈도를 줄이는데 도움이 되는 중재 (Intervention)의 개발에 정보를 줄 수 있을 것이다. Although Taekwondo has high injury rate and there are approximately black belts in Korea which is the highest population in the world, there is no well-organized injury surveillance system (ISS) in Korea. Therefore, the purpose of this study is 1) to describe descriptive Taekwondo epidemiology. 2) to examine difference in incidence of injury, types of location, body parts, type, activity, and mechanism, time-loss during a year follow-up in different age, gender, and event type groups. 3) to determine differences in incidence rate between a year follow-up and one competition taekwondo epidemiological data in age, gender groups. 4) to identify what the risk factor of the injury. Two-hundred eighty-five Korean taekwondo athletes voluntarily participated in this study. Injury and athlete-exposure (A-E) frequencies, injury rates (IR), odds ratios (OR), and rate ratios (RR) with 95% confidence intervals (CI) were calculated by age, sex, event type. Chi-square tests were used to compare the rate of injury between gender and age. During a season, 336 injuries were reported, for a rate of 6.39 per 1,000 A-E. The injury rate was found in competitions (23.09 per 1,000 A-E), practices (4.79 per 1000 A-E), and one competition (80.72 per 1,000 A-E). Most injuries occurred during practices (69.9%); however, the injury rate was higher in competitions than in practices (RR: 4.97; CI: 3.83 to 6.40). Youth athletes were significantly higher injury incidence as compared to that of adult athletes at practice (OR: 1.82; CI: 1.12 to 2.96), competition (OR: 2.00; CI: 1.06 to 3.60), and a single game (RR: 2.90; CI: 1.01 to 9.42). However, adult athletes are more likely to have more severe injuries (OR: 2.86; CI: 1.66 to 4.79). Youth athletes sustained injuries at a higher than adult athletes at both practice and competition. However, the proportion of injuries that were severe was higher in adults than adolescent populations. Future investigation into these differences in warranted. Continued ISS also can inform the development of interventions that will help to reduce the frequency and severity of injuries sustained by Taekwondo athletes.

The epidemiology of hepatitis E virus infections in rural Bangladesh

Labrique, Alain Bernard The Johns Hopkins University 2007 해외박사(DDOD)

Hepatitis E virus (HEV) is an emerging enteric pathogen responsible for most acute hepatitis worldwide. This dissertation presents data from studies conducted from 2001-2006 in the Matlab Health Research Center population under the International Center for Diarrheal Disease Research, Bangladesh. These studies define the previously unknown burden of HEV in rural Bangladesh and address gaps in HEV epidemiology. This work begins with a literature review, focusing on the challenges presented by this virus: the unexplained high case fatality in pregnancy, the absence of HEV in children, the rapid deterioration of immunity, and recent evidence implicating some HEV genotypes as zoonoses. The first study is a cross-sectional assessment of antibody seroprevalence to three hepatitis viruses (B,C&E) in a representative random population sample (n=1134). This study revealed a 22.5% seroprevalence of anti-HEV, 35.2% anti-HBc and 1.5% anti-HCV. Anti-HEV seroprevalence peaked in the second/third decades of life, as seen in India/Nepal. Male gender and outdoor employment were significantly associated with seropositivity. The second study follows this baseline cohort longitudinally for 18 months to determine HEV infection and disease rates. From 837 person-years (P-Y) of exposure, an incidence rate of 60.3/1000P-Y was estimated. Agespecific seroincidence increased in subsequent 10-year categories, peaking at 41-50y. Although clinical illness seemed infrequent, a disease:infection ratio as high as 49 per 100 (95%CI:31--73) was estimated. Third, an exploratory nested case control study attempts to identify putative risk factors for sporadic hepatitis E disease. Over 22 months, 13 field workers used a morbidity-scoring algorithm to identify acute hepatitis-like illness in their catchment population of 23,500. Finally, 46 confirmed HEV infections were compared to 134 sero-naive age-matched controls. Cases were less likely to be <15y, female or use unsanitary latrines in their homes. Outdoor employment, work outside the home, and travel to a town/city emerged as risk factors. Unlike in previous studies, recent contact with a "jaundice" patient and injection exposures were significant. These studies establish that: HEV is endemic in rural Bangladesh; sporadic infections are frequent in the absence of outbreaks; and, aside from classic hygiene risk factors, there may be other pathways through which HEV is transmitted.