A questão da causalidade em Epidemiologia / The issue of causality in Epidemiology

Resumo Este ensaio trata da questão da causalidade em epidemiologia a partir da década de 1970, cujo marco inicial aqui adotado foi a publicação de The causal thinking in health sciences, por M. Susser, até os dias de hoje, buscando elencar os vários movimentos filosóficos, teóricos e metodológicos que ao longo destes 50 anos buscaram refletir sobre o problema da causalidade na disciplina, tendo em vista o predomínio das pesquisas observacionais no campo. Partindo da contribuição seminal de Susser, foram discutidos vários movimentos, bem como as críticas a eles, tais como a proposta da adoção de lógica popperiana na década de 1980, a crítica aos modelos multicausais e a teoria ecossocial proposta por N. Krieger na década de 1990, as críticas à epidemiologia social também da década de 1990, a influência de J. Pearl e a adoção dos gráficos acíclicos direcionados como nova metodologia na questão da causalidade. A chamada revolução metodológica no início deste século e as críticas de filósofos e epidemiologistas a esta abordagem reducionista também foram revisadas, bem como as alternativas propostas nos últimos 10 anos, incluindo a perspectiva inferencialista, a triangulação de métodos e a defesa da epidemiologia social e de seus modelos de determinação.

Abstract This essay deals with the issue of causality in epidemiology from the 1970s onwards, whose starting point adopted here was the publication of The Causal Thinking in Health Sciences by M. Susser, up to the present day, seeking to list the various philosophical, theoretical and methods that throughout these 50 years have sought to reflect on the problem of causality in the discipline, in view of the predominance of observational research in the field. Starting from Susser's seminal contribution, several movements were discussed as well as their criticisms, such as the proposal to adopt Popperian logic on the 1980s, the criticism of multicausal models and the ecosocial theory proposed by N. Krieger in the 1990s, criticism of social epidemiology also in the 1990s, the influence of J.Pearl and the adoption of directed acyclic graphs as a new tool in the issue of causality. The so-called methodological revolution at the beginning of this century and the criticism of philosophers and epidemiologists to this reductionist approach were also reviewed, as well as the alternatives proposed in the last 10 years, including the inferentialist perspective, the triangulation of methods and the defense of social epidemiology and their determination models.

Violência familiar na infância, violência no namoro e saúde mental na adolescência / Family violence against children, dating violence and adolescent mental health

O objetivo geral desta tese foi conhecer as magnitudes e os padrões das violências no namoro na adolescência (VNA) e das violências familiares na infância (VFI), as repercussões da VFI nos diferentes padrões de VNA, bem como as relações entre os padrões de VFI e a saúde mental na adolescência. O objetivo geral suscitou três objetivos específicos, cada um explorado em um manuscrito. Os dados usados na tese derivaram da pesquisa "Estupro de vulnerável e outras violências contra adolescentes e jovens do sexo feminino", desenvolvida em 2017 e 2018 que contou com a participação de 721 estudantes de escolas públicas e privadas da IX Região Administrativa (RA) do Rio de Janeiro. Para identificar a VNA, a VFI e estimar a saúde mental, usou-se respectivamente as versões brasileiras do instrumento Conflict in Adolescent Dating Relationships Inventory (CADRI), do Childhood Trauma Questionnaire (CTQ) e do General Health Questionnaire (GHQ-12). As estratégias de análise de dados variaram em função dos diferentes objetivos/manuscritos. O manuscrito 1 estimou as magnitudes de exposição e perpetração das VNA entre os escolares da IX RA do município do Rio de Janeiro. A prevalência de vitimização variou de 16,7% (sexual) a 94,6% (emocional). A prevalência de perpetração variou entre 9,9% (sexual) e 94,6% (emocional). Os adolescentes que relataram serem vítimas de violência na infância, os que vivem em áreas violentas e os que consomem bebidas alcoólicas com maior frequência tiveram maior prevalência de VNA. Os manuscritos 2 e 3 utilizaram análises de classes latentes (ACL) para identificar os padrões de VNA (manuscrito 2) e o padrão de VFI (manuscrito 3) com base na agregação de indivíduos em classes, caracterizadas em função da probabilidade de endosso aos diferentes itens dos instrumentos CADRI e CTQ. Além da identificação destes padrões, buscou-se utilizar as classes estimadas em modelos causais aferindo os efeitos das dimensões de VFI para os padrões de VNA (manuscrito 2) e das classes de VFI para a saúde mental dos adolescentes (manuscrito 3). No manuscrito 2, identificou-se três classes latentes de VNA entre meninas e meninos. O abuso sexual na infância aumentou a chance de pertencer à classe mais grave de vitimização de VNA entre as meninas (OR = 5,72; IC 95% = 2,51-13,06). Os abusos emocionais (OR=5,97; IC 95% = 1,95-18,30) e físicos (OR=3,16; IC 95%=1,07-9,34) aumentaram as chances de classificar os meninos na classe mais grave de perpetração de VNA. A ACL do manuscrito 3 também identificou três classes de violência familiar na infância, tanto em meninas, como em meninos. Apesar de várias semelhanças entre as classes dos dois sexos, as meninas foram mais vítimas de abuso sexual e os meninos de punição corporal (castigo físico). Pertencer à classe mais grave de VFI aumentou os escores do GHQ-12 em 2 a 3 pontos quando comparados às classes mais brandas de violência. A partir destes resultados e com as discussões trazidas pelos três manuscritos, espera-se que esta tese tenha contribuído tanto com as discussões temáticas das violências, como apresentado alguns avanços metodológicos no campo da análise epidemiológica. Com relação aos primeiros aspectos, mais uma vez, evidenciou-se que a violência entre pais e filhos é um problema de saúde pública, por sua alta frequência e relações diretas e especificas com a violência no namoro de adolescentes; ampliou-se também os debates sobre a relação entre as violências e o gênero, na medida em que tanto as prevalências como os padrões de violência diferem entre meninos e meninas desde a infância; identificou-se padrões de violência que mostram que a vivência de diferentes tipos de abuso é a situação mais frequente entre crianças e adolescentes; percebeu-se que as repercussões das violências contra crianças na saúde mental de adolescentes dependem do padrão de coocorrência das diferentes formas de vitimização infantil. Com relação aos avanços metodológicos, a tese é inovadora por propor, pela primeira vez no Brasil, a utilização de ACL para caracterizar as violências contra crianças e em relacionamentos amorosos de adolescentes. Ademais, a tese avança ao articular a identificação de padrões de violência via análise de classes latentes com seus fatores de risco e consequências, ampliando as possibilidades de inferência dos modelos.

The main objective of this thesis was to know the magnitudes and patterns of dating violence in adolescence (DV) and family violence against children (VAC), the repercussions of on different DV patterns, and the relationship of VAC patterns to health mentality in adolescence. The general objective raised three specific goals. Each one was explored in one manuscript. The data used in the thesis were derived from the research "Rape of the vulnerable and other violence against female adolescents and young people", developed in 2017 and 2018, with 721 students from public and private schools in the IX Administrative Region (AR) of Rio de Janeiro. The Brazilian versions of the Conflict in Adolescent Dating Relationships Inventory (CADRI) instrument, the Childhood Trauma Questionnaire (CTQ) and the General Health Questionnaire (GHQ-12) were used to identify DV, VAC and to estimate mental health trends respectively. Data analysis strategies varied according to different objectives/manuscripts. Manuscript 1 estimated the magnitudes of exposure and perpetration of DV among students from the IX AR in Rio de Janeiro. The estimated victimization prevalence ranged from 16.7% (sexual) to 94.6% (emotional). The prevalence of perpetration ranged from 9.9% (sexual) to 94.6% (emotional). Adolescents who reported child abuse, those living in violent areas, and those who consumed alcohol more frequently had a higher prevalence of DV. Manuscripts 2 and 3 used latent classes analysis (LCA) to identify the DV patterns (manuscript 2) and the VAC pattern (manuscript 3) based on the aggregation of individuals into classes, characterized according to the probability of endorsement to the different items from the CADRI and CTQ instruments. In addition to identifying these patterns, we sought to use the estimated classes in causal models, assessing the effects of the VAC dimensions for the DV patterns (manuscript 2) and the VAC classes for adolescents' mental health (manuscript 3). In manuscript 2, three latent classes of DV were identified among girls and boys. Childhood sexual abuse increased the chance of belonging to the most severe class of DV victimization among girls (OR = 5.72; 95% CI = 2.51-13.06). Emotional (OR=5.97; 95% CI = 1.95-18.30) and physical (OR=3.16; 95% CI=1.07-9.34) abuse increased the chances of classifying boys in the most severe class of DV perpetration. The LCA of manuscript 3 also identified three classes of VAC, both in girls and boys. Despite several similarities between the classes of the two sexes, girls suffered more with sexual abuse and boys with corporal punishment (physical punishment). Belonging to the most severe class of VAC increased the GHQ-12 scores by 2 to 3 points compared to the milder classes of violence. Based on these results and with the discussions brought by the three manuscripts, it is expected that this thesis has contributed both to the thematic discussions of violence and presented some methodological advances in the field of epidemiological analysis. Regarding the first aspect, once again, it is evident that violence between parents and children is a public health problem due to its high frequency and direct and specific relationship with violence in adolescents' dating. Debates on the relationship between violence and gender have expanded, as both the prevalence and patterns of violence differ between boys and girls since childhood; patterns of violence were identified that indicate that experiencing different types of abuse is the most frequent situation among children and adolescents, and it was noticed that the repercussions of violence against children on the mental health of adolescents depend on the pattern of co-occurrence of different forms of child victimization. Regarding methodological advances, the thesis is innovative as it proposes the use of LCA to characterize VAC and DV for the first time in Brazil. Furthermore, the thesis advances by articulating the identification of patterns of violence via the analysis of latent classes with their risk factors and consequences, expanding the possibilities of inference from the models.

Covid-19 knowledge graphs in Health Communication and Information / Gráficos de conhecimento para Covid-19 em Comunicação e Informação sobre Saúde / Gráficos de conocimiento Covid-19 en Comunicación e Información de Salud

This commentary discusses recent developments in 'knowledge graph' technology over the course of the Covid-19 pandemic. Recently experiencing a surge in popularity, knowledge graphs are technologies that assist with data integration through structured metadata modeling. Researchers tag and collate vast amounts of diverse data using knowledge graphs, yet problems related to semantic drift and more salient issues related to the political economy of information and communication technologies persist. Researchers should anticipate that the semantics of these Covid-19 knowledge graphs can change over time. Equally important, researchers should also consider all stakeholders involved, including those stakeholders that might be excluded.

Este comentário discute desenvolvimentos recentes na tecnologia de 'gráficos de conhecimento' durante o curso da pandemia de Covid-19. Gráficos de conhecimento, que vêm tendo um aumento de popularidade, são tecnologias que auxiliam com a integração de dados através de modelamento estruturado de metadados. Pesquisadores rotulam e agregam vastas quantidades de dados diversos usando gráficos de conhecimento, entretanto persistem problemas relacionados a variações semânticas e questões mais salientes relacionadas à economia política de tecnologias de informação e comunicação. Os pesquisadores devem prever que a semântica desses gráficos de conhecimento para Covid-19 pode variar com o tempo. Igualmente importante, os pesquisadores devem também considerar todas as partes interessadas envolvidas, incluindo as que poderiam ser excluídas.

Este ejemplo analiza los desarrollos recientes en la tecnología de 'gráficos de conocimiento' durante la pandemia de Covid-19. Recientemente experimentando un aumento en popularidad, los gráficos de conocimiento son tecnologías que ayudan a la integración de datos a través del modelado de metadatos estructurados. Los investigadores etiquetan y recopilan grandes cantidades de datos diversos utilizando gráficos de conocimiento, pero persisten los problemas relacionados con la deriva semántica y cuestiones más importantes relacionadas con la economía política de las tecnologías de la información y la comunicación. Los investigadores deben prever que la semántica de estos gráficos de conocimiento de Covid-19 puede cambiar con el tiempo. También es importante que los investigadores consideren a todas las partes interesadas involucradas, incluso las que podrían quedar excluidas.

Método estadístico matemático para identificar el estado de la COVID-19 con relación al pico epidémico / Statistical and mathematical method to monitor COVID-19 status in relation to the peak of the epidemic

Introducción: Varios modelos han intentado pronosticar y evaluar el estado actual de la pandemia que ha generado el coronavirus SARVS-CoV2, siendo la evaluación la base fundamental para la toma de decisiones. Por ello, la importancia de identificar el estado de la COVID-19 en un lapso seleccionado es un proceso de gestión de información muy importante, el cual puede realizarse a través de métodos estadísticos y matemáticos con el fin de tomar decisiones para controlar la epidemia. Objetivo: Proponer un método estadístico matemático para identificar el estado de la COVID-19 con relación al pico epidémico en lapsos escogidos. Método: Se utilizaron métodos teóricos entre los que destacan el análisis, la síntesis y la abstracción, y otros de carácter puramente matemáticos. Resultados: Como resultado de la aplicación práctica del método se generan gráficos que ofrecen información válida y confiable para un eficaz proceso de toma de decisiones. Conclusiones: Esta propuesta muestra robustez teórica y eficacia práctica que, aunque se elabora teniendo en cuenta los datos de Cuba, es extrapolable a cualquier otro país, e incluso a provincias y municipios(AU)

Introduction: Several models have tried to predict and evaluate the current status of the pandemic that the new coronavirus, labeled SARVS-CoV2, has caused. This evaluation would be the basis for decision making. Therefore, the importance of monitoring the COVID-19 status in a selected period of time is very important for the process of information management, which can be done through statistical and mathematical methods in order to make big decisions to control the epidemic. Objective: To propose a mathematical and statistical method to monitor COVID-19 status in contrast to the peak of the epidemic in a selected period of time. Method: Several theoretical methods were used, specially: analysis, synthesis, abstract; and other purely mathematical methods. Results: As a result of the practical application of the methods used, valid and reliable information was generated in charts, supporting an effective process of decision making. Conclusions: This proposal shows the robustness of its theoretical aspects and a practical effectiveness that, even if elaborated to submit Cuban-generated national data, it could be used in other countries, and even in a provincial or municipal level(AU)

Método estadístico matemático para identificar el estado de la COVID-19 con relación al pico epidémico / Statistical and mathematical method to monitor COVID-19 status in relation to the peak of the epidemic

RESUMEN Introducción: Varios modelos han intentado pronosticar y evaluar el estado actual de la pandemia que ha generado el coronavirus SARVS-CoV2, siendo la evaluación la base fundamental para la toma de decisiones. Por ello, la importancia de identificar el estado de la COVID-19 en un lapso seleccionado es un proceso de gestión de información muy importante, el cual puede realizarse a través de métodos estadísticos y matemáticos con el fin de tomar decisiones para controlar la epidemia. Objetivo: Proponer un método estadístico matemático para identificar el estado de la COVID-19 con relación al pico epidémico en lapsos escogidos. Método: Se utilizaron métodos teóricos entre los que destacan el análisis, la síntesis y la abstracción, y otros de carácter puramente matemáticos. Resultados: Como resultado de la aplicación práctica del método se generan gráficos que ofrecen información válida y confiable para un eficaz proceso de toma de decisiones. Conclusiones: Esta propuesta muestra robustez teórica y eficacia práctica que, aunque se elabora teniendo en cuenta los datos de Cuba, es extrapolable a cualquier otro país, e incluso a provincias y municipios.

ABSTRACT Introduction: Several models have tried to predict and evaluate the current status of the pandemic that the new coronavirus, labeled SARVS-CoV2, has caused. This evaluation would be the basis for decision making. Therefore, the importance of monitoring the COVID-19 status in a selected period of time is very important for the process of information management, which can be done through statistical and mathematical methods in order to make big decisions to control the epidemic. Objective: To propose a mathematical and statistical method to monitor COVID-19 status in contrast to the peak of the epidemic in a selected period of time. Method: Several theoretical methods were used, specially: analysis, synthesis, abstract; and other purely mathematical methods. Results: As a result of the practical application of the methods used, valid and reliable information was generated in charts, supporting an effective process of decision making. Conclusions: This proposal shows the robustness of its theoretical aspects and a practical effectiveness that, even if elaborated to submit Cuban-generated national data, it could be used in other countries, and even in a provincial or municipal level.

Detection bias:structural analysis of different study designs / 上海预防医学

Detection bias is an information bias.It was first proposed by Horwitz from the study investigating the association of the administration of estrogen after menopause with the occurrence of endometrial cancer, which still prevails in most epidemiological studies.We use the Directed Acyclic Graph to analyze the effect of a given exposure on a specific outcome with the association estimates between the measured exposure and outcome.Detection bias occurs when there is additional open paths irrelevant to the target path of interest which is originated from measured exposure to measured outcome.We further analyzed how the detection bias was formed under different study designs, including cohort study, randomized clinical trial and case-control study in order to further investigate its potential influence on the effect/association estimation.

Detection bias:structural analysis of different study designs / 上海预防医学

Detection bias is an information bias.It was first proposed by Horwitz from the study investigating the association of the administration of estrogen after menopause with the occurrence of endometrial cancer, which still prevails in most epidemiological studies.We use the Directed Acyclic Graph to analyze the effect of a given exposure on a specific outcome with the association estimates between the measured exposure and outcome.Detection bias occurs when there is additional open paths irrelevant to the target path of interest which is originated from measured exposure to measured outcome.We further analyzed how the detection bias was formed under different study designs, including cohort study, randomized clinical trial and case-control study in order to further investigate its potential influence on the effect/association estimation.

Influence of the concrete and abstract graphs on N200 and P300 potentials / 生物医学工程学杂志

Increasing the amplitude of event-related potential is one of the key methods to improve the accuracy of the potential-based brain-computer interface, e.g., P300-based brain-computer interface. The brain-computer interface systems often use symbols or controlled objects as vision stimuli, but what visual stimuli can induce more obvious event-related potential is still unknown. This paper designed three kinds of visual stimuli, i.e., a square, an arrow, and a robot attached with an arrow, to analyze the influence of concreteness degree of the graph on the N200 and P300 potentials, and applied a support vector machine to compare the performance of the brain-computer interface under different stimuli. The results showed that, compared with the square, the robot attached with arrow and the arrow both induced larger N200 potential ( = 1.6 × 10 , = 4.2 × 10 ) and longer P300 potential ( = 2.2 × 10 , = 1.9 × 10 ) in the frontal area, but the amplitude under the arrow condition is smaller than the one under the robot attached with arrow condition. The robot attached with arrow increased the N200 potential amplitude of the square and arrow from 3.12 μV and 5.19 μV to 7.21 μV ( = 1.6 × 10 , = 8.9 × 10 ), and improved the accuracy rate from 59.95%, 61.67% to 74.45% ( = 2.1 × 10 , = 1.6 × 10 ), and the information transfer rate from 35.00 bits/min, 35.98 bits/min to 56.71 bits/min ( = 2.6 × 10 , = 1.6 × 10 ). This study shows that the concreteness of graphics could affect the N200 potential and the P300 potential. The abstract symbol could represent the meaning and evoke potentials, but the information contained in the concrete robot attached with an arrow is more correlated with the human experience, which is helpful to improve the amplitude. The results may provide new sight in modifying the stimulus interface of the brain-computer interface.

Study on the status quo and quality evaluation of data graphs and tables based on academic medical journals in Shanghai universities / 中华医学科研管理杂志

Objective To evaluate the quantity and quality of graphs and tables in medical literature.Methods We conducted a retrospective survey of 750 randomly selected original research articles,from 2011-2015 issues of 5 academic medical journals by using a stratified random sampling method.Paper characteristics,application status,quantity and quality of graphs and tables were analyzed.Results More than 48％ of original research articles contained at least 1 table or graph.The highest frequency of using table and graph was in clinical research.The number of tables and the number of articles with tables were both significantly decreased during 2011-2015 (P=0.034).The most common errors in tables were the inconsistent decimal number and the presentation of numeric data without right alignment.Only 12％ of the articles contained at least 1 graph.Ofthe 175 graphs,bar chart with intervals predominated.Compared with other domains,the completeness of graphs was excellence.Conclusions The result expression in medical research is still dominated by tables.And the quality of graphs is much better than tables.

Complejidad argumentativa individual escrita en estudiantes universitarios ingresantes y avanzados / Written individual argumentative complexity of first-year and senior university students

La investigación compara la complejidad argumentativa individual escrita en tareas sociocientíficas de estudiantes universitarios de Psicología en función del momento de cursado (ingresante/avanzado) y de la presencia de un sistema de representación externa adicional (gráfico). Participaron 72 estudiantes de una universidad argentina. Estos emitieron opinión escrita sobre una situación sociocientífica con argumentos a favor y en contra, y un grupo dispuso de un sistema de información adicional (gráfico). Se codificaron las producciones según: (a) si se trataba de un texto argumentativo; (b) en los textos argumentativos, se consideraron cantidad de argumentos, diferencia de opinión principal, estructura argumentativa, sesgo confirmatorio y (c) uso de información. Los resultados indicaron una relación entre los estudiantes ingresantes y la producción de textos no argumentativos, por un lado, y de los estudiantes avanzados y la producción de textos argumentativos, por el otro. Se discuten las implicancias de los resultados en relación a la comprensión teórica de la competencia argumentativa y la creación de material educativo para la formación universitaria.

The research compares the written individual argumentative complexity in socio-scientific tasks of psychology university students, based on the year of study (first-year/senior student) and the presence of an additional external representation system (graph). Seventy-two (72) students from an Argentine university participated in the study. They gave their written opinion about a socio-scientific situation that included arguments for and against it, and a group received an additional information system (graph). The productions were coded according to: (a) whether it was an argumentative text; (b) the number of arguments, difference from the main opinion, argumentative structure, and confirmatory bias in the argumentative texts; and (c) the use of information. The results showed a relationship between first-year students and the production of non-argumentative texts, and a relationship between senior students and the production of argumentative texts. The results of the theoretical conceptualization of the argumentative competence, and the design of educational materials for university training are discussed.

Application of directed acyclic graphs in evidence-based medicine / 中国医师杂志

Evidence-based medicine (EBM) is a kind of clinic practice where clinicians use the best and the latest available evidence to diagnose and treat patients, and both evidence providers and users need to identify and control different kinds of biases in medical research.Directed acyclic graphsis is a tool to explore the causal relationship.The possible biases in the study can be revealed in a simple graphical language.The use of directed acyclic graphs could avoid the occurrence of bias and improve the quality of medical research and better guide clinical practice.

A structural classification of strategies for confounding control in research design / 中华流行病学杂志

Confounding affects the causal relation among the population.Depending on whether the confounders are known,measurable or measured,they can be divided into four categories.Based on Directed Acyclic Graphs,the strategies for confounding control can be classified as (1) the broken-confounding-path method,which can be further divided into single and dual broken paths,corresponding to exposure complete intervention,restriction and stratification,(2) and the reserved-confounding-path method,which can be further divided into incomplete exposure intervention (in instrumental variable design and non-perfect random control test),mediator method and matching method.Among them,random control test,instrumental variable design or Mendelian randomized design,mediator method can meet the requirements for controlling all four types of confounders,while the restriction,stratification and matching methods are only applicable to known,measurable and measured confounders.Identifying the mechanisms of confounding control is a prerequisite for obtaining correct causal effect estimates,which will be helpful in research design.

Exposure-preceding-outcome regarding time sequence among cohort studies in real world / 中华流行病学杂志

One of the commonly accepted merits of cohort studies (CSs) refers to the exposure precedes outcome superior to other observational designs.We use Directed Acyclic Graphs to construct a causal graph among research populations under CSs.We notice that the substitution of research population in place of a susceptible one can be used for effect estimation.Its correctness depends on the outcome-free status of the substituted population and the performance of both screening and diagnosis regarding the outcomes under study at baseline.The temporal precedence of exposure over outcome occurs theoretically,despite the opposite happens in realities.Correct effect estimate is affected by both the suitability of population substitution and the validities of outcome identification and exclusion.

Causality in objective world: Directed Acyclic Graphs-based structural parsing / 中华流行病学杂志

The overall details of causality frames in the objective world remain obscure,which poses difficulty for causality research.Based on the temporality of cause and effect,the objective world is divided into three time zones and two time points,in which the causal relationships of the variables are parsed by using Directed Acyclic Graphs (DAGs).Causal DAGs of the world (or causal web) is composed of two parts.One is basic or core to the whole DAGs,formed by the combination of any one variable originating from each time unit mentioned above.Cause effect is affected by the confounding only.The other is an internal DAGs within each time unit representing a parent-child or ancestor-descendant relationship,which exhibits a structure similar to the confounding.This paper summarizes the construction of causality frames for objective world research (causal DAGs),and clarify a structural basis for the control of the confounding in effect estimate.

Dynamic path analysis on life course epidemiology / 中华流行病学杂志

In the studies of modem epidemiology,exposure in a short term cannot fully elaborate the mechanism of the development of diseases or health-related events.Thus,lights have been shed on to life course epidemiology,which studies the exposures in early life time and their effects related to the development of chronic diseases.When exploring the mechanism leading from one exposure to an outcome and its effects through other factors,due to the existence of time-variant effects,conventional statistic methods could not meet the needs of etiological analysis in life course epidemiology.This paper summarizes the dynamic path analysis model,including the model structure and significance,and its application in life course epidemiology.Meanwhile,the procedure of data processing and etiology analyzing were introduced.In conclusion,dynamic path analysis is a useful tool which can be used to better elucidate the mechanisms that underlie the etiology of chronic diseases.

A structural classification of strategies for confounding control in research design / 中华流行病学杂志

Confounding affects the causal relation among the population.Depending on whether the confounders are known,measurable or measured,they can be divided into four categories.Based on Directed Acyclic Graphs,the strategies for confounding control can be classified as (1) the broken-confounding-path method,which can be further divided into single and dual broken paths,corresponding to exposure complete intervention,restriction and stratification,(2) and the reserved-confounding-path method,which can be further divided into incomplete exposure intervention (in instrumental variable design and non-perfect random control test),mediator method and matching method.Among them,random control test,instrumental variable design or Mendelian randomized design,mediator method can meet the requirements for controlling all four types of confounders,while the restriction,stratification and matching methods are only applicable to known,measurable and measured confounders.Identifying the mechanisms of confounding control is a prerequisite for obtaining correct causal effect estimates,which will be helpful in research design.

Exposure-preceding-outcome regarding time sequence among cohort studies in real world / 中华流行病学杂志

One of the commonly accepted merits of cohort studies (CSs) refers to the exposure precedes outcome superior to other observational designs.We use Directed Acyclic Graphs to construct a causal graph among research populations under CSs.We notice that the substitution of research population in place of a susceptible one can be used for effect estimation.Its correctness depends on the outcome-free status of the substituted population and the performance of both screening and diagnosis regarding the outcomes under study at baseline.The temporal precedence of exposure over outcome occurs theoretically,despite the opposite happens in realities.Correct effect estimate is affected by both the suitability of population substitution and the validities of outcome identification and exclusion.

Causality in objective world: Directed Acyclic Graphs-based structural parsing / 中华流行病学杂志

The overall details of causality frames in the objective world remain obscure,which poses difficulty for causality research.Based on the temporality of cause and effect,the objective world is divided into three time zones and two time points,in which the causal relationships of the variables are parsed by using Directed Acyclic Graphs (DAGs).Causal DAGs of the world (or causal web) is composed of two parts.One is basic or core to the whole DAGs,formed by the combination of any one variable originating from each time unit mentioned above.Cause effect is affected by the confounding only.The other is an internal DAGs within each time unit representing a parent-child or ancestor-descendant relationship,which exhibits a structure similar to the confounding.This paper summarizes the construction of causality frames for objective world research (causal DAGs),and clarify a structural basis for the control of the confounding in effect estimate.

Dynamic path analysis on life course epidemiology / 中华流行病学杂志

In the studies of modem epidemiology,exposure in a short term cannot fully elaborate the mechanism of the development of diseases or health-related events.Thus,lights have been shed on to life course epidemiology,which studies the exposures in early life time and their effects related to the development of chronic diseases.When exploring the mechanism leading from one exposure to an outcome and its effects through other factors,due to the existence of time-variant effects,conventional statistic methods could not meet the needs of etiological analysis in life course epidemiology.This paper summarizes the dynamic path analysis model,including the model structure and significance,and its application in life course epidemiology.Meanwhile,the procedure of data processing and etiology analyzing were introduced.In conclusion,dynamic path analysis is a useful tool which can be used to better elucidate the mechanisms that underlie the etiology of chronic diseases.

Coherence analysis of EEG in locomotion using graphs / Análisis de coherencia de señales EEG en locomoción usando grafos

Abstract: One of the most interesting brain machine interface (BMI) applications, is the control of assistive devices for rehabilitation of neuromotor pathologies. This means that assistive devices (prostheses, orthoses, or exoskeletons) are able to detect user motion intention, by the acquisition and interpretation of electroencephalographic (EEG) signals. Such interpretation is based on the time, frequency or space features of the EEG signals. For this reason, in this paper a coherence-based EEG study is proposed during locomotion that along with the graph theory allows to establish spatio-temporal parameters that are characteristic in this study. The results show that along with the temporal features of the signal it is possible to find spatial patterns in order to classify motion tasks of interest. In this manner, the connectivity analysis alongside graphs provides reliable information about the spatio-temporal characteristics of the neural activity, showing a dynamic pattern in the connectivity during locomotions tasks.

Resumen: Una de las aplicaciones de las interfaces cerebro máquina (BMI, por las siglas en Inglés de brain machine interface) que en la actualidad han tenido mucho interés es el control de dispositivos de asistencia en rehabilitación de patologías neuromotrices. Esto es, que los dispositivos (prótesis, órtesis o exoesqueletos) tengan la capacidad de ejecutar la intención de movimiento del usuario, a través de la interpretación de las señales electroencefalográficas (EEG). Dicha interpretación se basa en el conocimiento de características en diferentes dominios de la señal EEG i.e., el dominio del tiempo, de la frecuencia o del espacio. Por tal motivo, en este trabajo proponemos un estudio sobre la coherencia de las señales EEG durante actividades de locomoción que, por medio de la teoría de grafos, nos permita establecer parámetros espacio-temporales característicos de las actividades motrices propuestas. Los resultados muestran que, además de las características temporales de la señal, es posible encontrar patrones espaciales que ayuden a clasificar las tareas motrices de interés. Esto es, el análisis de conectividad complementado con sus grafos asociados proporciona información confiable sobre las características espacio-temporales de la actividad neural, reflejando la dinámica de sus ajustes en correspondencia con distintos niveles de conectividad durante la marcha.