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1.
BMC Neurol ; 22(1): 8, 2022 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-34979977

RESUMO

BACKGROUND: Growing evidence suggests a mutual interaction between gut microbiome alterations and ALS pathogenesis. However, previous studies were susceptible to potential confounding factors and reverse causation bias, likely leading to inconsistent and biased results. OBJECTIVES: To decipher the potentially mutual relationship between gut microbiota and ALS, we used a bidirectional two-sample MR approach to examine the associations between the gut microbiome and ALS. RESULTS: Using the inverse variance-weighted method, OTU10032 unclassified Enterobacteriaceae species-level OTU and unclassified Acidaminococcaceae were associated with a higher risk of ALS (per relative abundance: OR, 1.04; 95% CI, 1.01-1.07; P = 0.011 and OR, 1.02; 95% CI, 1.01-1.04; P = 0.009, respectively). Importantly, Gamma-Glu-Phe was showed potential deleterious effects on the risk of ALS (genetically predicted per a 1-standard deviation increase in the level of Gamma-Glu-Phe: OR, 1.96; 95% CI, 1.50-2.55; P = 0.012). Sensitivity analysis of the two candidate genera and metabolites using the MR-Egger and weighted-median methods produced similar estimates, and no horizontal pleiotropy or outliers were observed. Intriguingly, genetically predicted ALS was associated with an increase in the relative abundance of OTU4607_Sutterella (per 1-unit higher log odds: ß, 2.23; 95% CI, 1.27-3.18; P = 0.020) and Lactobacillales_ORDER (per 1-unit higher log odds: ß, 0.51; 95% CI, 0.09-0.94; P = 0.019). CONCLUSIONS: Our findings provide novel evidence supporting the bidirectional relationship between the gut microbiota and ALS. These results may contribute to designing microbiome- and microbiome-dependent metabolite interventions in future ALS clinical trials.


Assuntos
Esclerose Amiotrófica Lateral , Microbioma Gastrointestinal , Esclerose Amiotrófica Lateral/epidemiologia , Esclerose Amiotrófica Lateral/genética , Causalidade , Estudo de Associação Genômica Ampla , Humanos , Análise da Randomização Mendeliana , Polimorfismo de Nucleotídeo Único
2.
Nonlinear Dynamics Psychol Life Sci ; 26(1): 105-121, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34973162

RESUMO

This study investigated the existence of chaotic structure in voting behavior by considering non-economic and macroeconomic factors in Turkey during the period of 03.1986-01.2020. The chaotic structure among the analyzed variables was characterized by Lyapunov exponents that explore the chaotic dynamics of the series. Following, the effects of inflation, unemployment, economic growth and terror on party votes were analyzed by Fourier regression model. Then, the causality among the macroeconomic variables, terror and party groups was analyzed by the Granger causality method. According to our results, there is unidirectional causality from terror to all four party groups. In the context of macroeconomic variables, there is the evidence of bidirectional causality between conservative parties and inflation; unidirectional causality from inflation to center-right and center-left parties. There is no causality between nationalist parties and inflation. Furthermore, center-right and center-left parties have the evidence of no causality with unemployment while there is unidirectional causality from unemployment to conservative and nationalist parties. There is unidirectional causality from economic growth to conservative parties and bidirectional causality between center-right parties and economic growth. However, the center-left and nationalist parties are not the sources of Granger causality of economic growth, and there is no inverse Granger causality relationship between these variables. Therefore, it can be concluded that between the periods 03.1986-01.2020, there was no concern for economic growth in left-wing and nationalist-based parties in Turkey.


Assuntos
Desenvolvimento Econômico , Política , Causalidade , Humanos , Turquia , Desemprego
3.
Acta Neurochir Suppl ; 134: 75-78, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-34862530

RESUMO

There is an increasing interest in using prediction models to forecast clinical outcomes within the fields of neurosurgery and clinical neuroscience. The present chapter outlines the foundations of Bayesian learning and introduces Bayes theorem and its use in machine learning methodology. The use of Bayesian networks to structure and define associations between outcome predictors and final outcomes is highlighted and Naïve Bayes classifiers are outlined for use in predicting neurosurgical outcomes, where the understanding of underlying causes is less important. The present work aims to orient researchers in Bayesian machine learning methods and when and how to use them. When used correctly, these tools have the potential to improve the understanding of factors influencing neurosurgical outcomes, aid in structuring the relationships between them, and provide reliable machine learning classification models for predicting neurosurgical outcomes.


Assuntos
Algoritmos , Neurocirurgia , Teorema de Bayes , Causalidade , Aprendizado de Máquina
4.
Pac Symp Biocomput ; 27: 73-84, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-34890138

RESUMO

The advent of simultaneously collected imaging-genetics data in large study cohorts provides an unprecedented opportunity to assess the causal effect of brain imaging traits on externally measured experimental results (e.g., cognitive tests) by treating genetic variants as instrumental variables. However, classic Mendelian Randomization methods are limited when handling high-throughput imaging traits as exposures to identify causal effects. We propose a new Mendelian Randomization framework to jointly select instrumental variables and imaging exposures, and then estimate the causal effect of multivariable imaging data on the outcome. We validate the proposed method with extensive data analyses and compare it with existing methods. We further apply our method to evaluate the causal effect of white matter microstructure integrity (WM) on cognitive function. The findings suggest that our method achieved better performance regarding sensitivity, bias, and false discovery rate compared to individually assessing the causal effect of a single exposure and jointly assessing the causal effect of multiple exposures without dimension reduction. Our application results indicated that WM measures across different tracts have a joint causal effect that significantly impacts the cognitive function among the participants from the UK Biobank.


Assuntos
Variação Genética , Análise da Randomização Mendeliana , Causalidade , Biologia Computacional , Humanos , Neuroimagem
5.
Int J Cancer ; 150(2): 303-307, 2022 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-34449871

RESUMO

Epidemiological evidence is consistent with a protective effect of vitamin D against colorectal cancer (CRC), but the observed strong associations are open to confounders and potential reverse causation. Previous Mendelian randomisation (MR) studies were limited by poor genetic instruments and inadequate statistical power. Moreover, whether genetically higher CRC risk can influence vitamin D level, namely the reverse causation, still remains unknown. Herein, we report the first bidirectional MR study. We employed 110 newly identified genetic variants as proxies for vitamin D to obtain unconfounded effect estimates on CRC risk in 26 397 CRC cases and 41 481 controls of European ancestry. To test for reserve causation, we estimated effects of 115 CRC-risk variants on vitamin D level among 417 580 participants from the UK Biobank. The causal association was estimated using the random-effect inverse-variance weighted (IVW) method. We found no significant causal effect of vitamin D on CRC risk [IVW estimate odds ratio: 0.97, 95% confidence interval (CI) = 0.88-1.07, P = .565]. Similarly, no significant reverse causal association was identified between genetically increased CRC risk and vitamin D levels (IVW estimate ß: -0.002, 95% CI = -0.008 to 0.004, P = .543). Stratified analysis by tumour sites did not identify significant causal associations in either direction between vitamin D and colon or rectal cancer. Despite the improved statistical power of this study, we found no evidence of causal association of either direction between circulating vitamin D and CRC risk. Significant associations reported by observational studies may be primarily driven by unidentified confounders.


Assuntos
Neoplasias Colorretais/epidemiologia , Estudo de Associação Genômica Ampla , Análise da Randomização Mendeliana/estatística & dados numéricos , Polimorfismo de Nucleotídeo Único , Vitamina D/sangue , Vitaminas/sangue , Estudos de Casos e Controles , Causalidade , Neoplasias Colorretais/sangue , Neoplasias Colorretais/genética , Seguimentos , Humanos , Prognóstico , Fatores de Risco , Reino Unido/epidemiologia
6.
Washington D.C; Organización Panamericana de la Salud; 1 ed; Dic. 2021. 37 p. ilus.
Monografia em Espanhol | LIPECS, MINSAPERÚ | ID: biblio-1352620

RESUMO

En el caso del sector salud, los intercambios se realizan entre determinados grupos o personas y personal de salud capacitado. Su objetivo es, entre otros, mejorar el acceso a los servicios de salud y construir salud intercultural, con énfasis en la resolución de problemas previamente planteados y sus causas, la comprensión mutua y la creación de vínculos sólidos. La presente publicación, que contiene la metodología para aplicar en este campo, está dirigida a personal de salud o de otras áreas y sectores, quienes facilitarán los diálogos de saberes. En este caso, se trata de personas designadas para catalizar los procesos relacionados con dichos diálogos, los cuales constituyen una necesidad en el proceso de comunicación con grupos poblacionales diversos, entre ellos las poblaciones indígenas, afrodescendientes y romaníes, aunque en rigor la metodología puede aplicarse al trabajo con todo colectivo, como por ejemplo migrantes, desplazados, adolescentes, personas mayores, etc., que presente problemas de acceso y cobertura universal de salud


Assuntos
Grupos Étnicos , Causalidade , Grupos Populacionais , Grupo com Ancestrais do Continente Africano , Grupo com Ancestrais Nativos do Continente Americano , Tráfico de Pessoas , Assistência à Saúde Culturalmente Competente , Cobertura Universal de Saúde , Povos Indígenas , Acesso aos Serviços de Saúde
7.
Rev Alerg Mex ; 68(4): 291-299, 2021.
Artigo em Espanhol | MEDLINE | ID: mdl-34904564

RESUMO

In developing a research protocol, authors must consider the possible errors that may occur throughout the study. In clinical research, two types of biases are recognized: random errors and systematic errors; the latter are called biases. To date, dozens of biases have been described, which is why the purpose of this article is to describe the main biases that can occur in clinical research studies, as well as strategies to avoid them or to minimize their effects. Since there are several classifications, in order to provide a more practical overview in this review, the biases are grouped into three types: selection biases, information (or performance) biases, and confounding biases. In addition, to make it even more specific, we describe the biases considering the purpose of the research: prognosis, therapeutics, causality, and diagnostic test studies.


Assuntos
Viés , Causalidade , Humanos
8.
BMC Infect Dis ; 21(1): 1254, 2021 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-34906101

RESUMO

BACKGROUND: Preventing respiratory tract infections (RTIs) could have profound effects on quality of life, primary care workload, antibiotic prescribing and stewardship. We aimed to identify factors that increase and decrease RTI acquisition within Organisation for Economic Cooperation and Development (OECD) member countries. METHODS: Systematic search of Medline, Embase, Cochrane and ISI Web of Knowledge for studies conducted up to July 2020 reporting predisposing factors for community RTI acquisition. Pooled odds ratios were calculated using a random-effects model. RESULTS: 23 studies investigated risk factors associated with community-acquired pneumonia (n = 15); any RTI (n = 4); influenza like illness (n = 2); and lower RTI (n = 2). Demographic, lifestyle and social factors were: underweight BMI (pooled odds ratio (ORp 2.14, 95% CI 1.58 to 2.70, p = 0.97); male sex (ORp 1.30, 95% CI 1.27 to 1.33, p = 0.66); contact with pets (ORp 1.35, 95% CI 1.16 to 1.54, p = 0.72); contact with children (ORp 1.35, 95% CI 1.15 to 1.56, p = 0.05); and ex-smoking status (ORp 1.57, 95% CI 1.26 to 1.88, p = 0.76). Health-related factors were: chronic liver condition (ORp 1.30, 95% CI 1.09 to 1.50, p = 0.34); chronic renal condition (ORp 1.47, 95% CI 1.09 to 1.85, p = 0.14); and any hospitalisation in previous five years (ORp 1.64, 95% CI 1.46 to 1.82, p = 0.66). CONCLUSIONS: We identified several modifiable risk factors associated with increased likelihood of acquiring RTIs in the community, including low BMI, contact with children and pets. Modification of risk factors and increased awareness of vulnerable groups could reduce morbidity, mortality and antibiotic use associated with RTIs. PROSPERO REGISTRATION: CRD42019134176.


Assuntos
Infecções Comunitárias Adquiridas , Infecções Respiratórias , Antibacterianos/uso terapêutico , Causalidade , Criança , Infecções Comunitárias Adquiridas/tratamento farmacológico , Infecções Comunitárias Adquiridas/epidemiologia , Humanos , Masculino , Qualidade de Vida , Infecções Respiratórias/tratamento farmacológico , Infecções Respiratórias/epidemiologia
9.
Nat Commun ; 12(1): 7274, 2021 12 14.
Artigo em Inglês | MEDLINE | ID: mdl-34907193

RESUMO

Mendelian Randomisation (MR) is an increasingly popular approach that estimates the causal effect of risk factors on complex human traits. While it has seen several extensions that relax its basic assumptions, most suffer from two major limitations; their under-exploitation of genome-wide markers, and sensitivity to the presence of a heritable confounder of the exposure-outcome relationship. To overcome these limitations, we propose a Latent Heritable Confounder MR (LHC-MR) method applicable to association summary statistics, which estimates bi-directional causal effects, direct heritabilities, and confounder effects while accounting for sample overlap. We demonstrate that LHC-MR outperforms several existing MR methods in a wide range of simulation settings and apply it to summary statistics of 13 complex traits. Besides several concordant results with other MR methods, LHC-MR unravels new mechanisms (how disease diagnosis might lead to improved lifestyle) and reveals new causal effects (e.g. HDL cholesterol being protective against high systolic blood pressure), hidden from standard MR methods due to a heritable confounder of opposite effect direction.


Assuntos
Estudo de Associação Genômica Ampla/métodos , Causalidade , HDL-Colesterol/genética , Simulação por Computador , Pleiotropia Genética , Estudo de Associação Genômica Ampla/estatística & dados numéricos , Humanos , Hipertensão/epidemiologia , Hipertensão/genética , Análise da Randomização Mendeliana , Modelos Estatísticos , Herança Multifatorial
10.
Curr Protoc ; 1(12): e335, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34936225

RESUMO

Mendelian randomization is a framework that uses measured variation in genes for assessing and estimating the causal effect of an exposure on an outcome. Multivariable Mendelian randomization is an extension that can assess the causal effect of multiple exposures on an outcome, and can be advantageous when considering a set (>1) of potentially correlated candidate risk factors in evaluating the causal effect of each on a health outcome, accounting for measured pleiotropy. This can be seen, for example, in determining the causal effects of lipids and cholesterol on type 2 diabetes risk, where the correlated risk factors share genetic predictors. Similar to univariate Mendelian randomization, multivariable Mendelian randomization can be conducted using two-sample summary-level data where the gene-exposure and gene-outcome associations are derived from separate samples from the same underlying population. Here, we present a protocol for conducting a two-sample multivariable Mendelian randomization study using the 'MVMR' package in R and summary-level genetic data. We also provide a protocol for searching and obtaining instruments using available data sources in the 'MRInstruments' R package. Finally, we provide general guidelines and discuss the utility of performing a multivariable Mendelian randomization analysis for simultaneously assessing causality of multiple exposures. © 2021 Wiley Periodicals LLC. Basic Protocol: Performing a two-sample multivariable Mendelian randomization analysis using the 'MVMR' package in R and summarized genetic data Support Protocol 1: Installing the 'MVMR' R package Support Protocol 2: Obtaining instruments from the 'MRInstruments' R package.


Assuntos
Diabetes Mellitus Tipo 2 , Análise da Randomização Mendeliana , Causalidade , Variação Genética , Humanos , Fatores de Risco
11.
SMAD, Rev. eletrônica saúde mental alcool drog ; 17(4): 14-22, out.-dez. 2021. ilus
Artigo em Português | LILACS, Index Psicologia - Periódicos | ID: biblio-1347837

RESUMO

OBJETIVO: este estudo teve como objetivo investigar os níveis de Burnout e possíveis fatores predisponentes entre militares do Exército Brasileiro que estavam servindo na Amazônia Brasileira. MÉTODO: a amostra foi composta por 122 militares (oficiais e sargentos) voluntários com idade média de 36,80 ± 6,69 anos, 53 empregados nas missões operacionais (segurança nas fronteiras, patrulha, exercícios de defesa externa e interna) e 69 empregados nas missões administrativas (logística interna). Foram selecionados oficiais (29) e sargentos (93) servindo em Porto Velho, noroeste do Brasil. Eles responderam a um questionário sociodemográfico e ao Maslach Burnout Inventory, validado para o Brasil. RESULTADOS: os resultados mostraram que os níveis de esgotamento nos militares do Exército que servem na região são altos. As principais condições sociodemográficas, trabalhistas, físicas e sociais associadas a níveis significativamente mais altos de esgotamento no presente estudo foram: redução do tempo de serviço, estilo de vida sedentário, trabalho extra, menor hierarquia e morar longe dos familiares. CONCLUSÃO: a interação entre os dois instrumentos constatou que os militares que atuam na área operacional, entre 6 e 10 anos de serviço, solteiros, que exercem pouca atividade física e cujos familiares moram longe foram os que possuíam o maiores níveis de Burnout.


OBJECTIVE: this study aimed to investigate the Burnout levels and possible predisposing factors among Brazilian Army military who were serving in the Brazilian Amazon. METHOD: the sample consisted of 122 volunteer military (officers and sergeants) with a mean age of 36.80 ± 6.69 years, 53 were employed in the operational missions (border security, patrol, external and internal defense exercises) and 69 personnel who were employed in the administrative missions (internal logistics). Officers (29) and sergeants (93) were selected who served in Porto Velho, northwestern Brazil. They answered to a sociodemographic questionnaire and the Maslach Burnout Inventory, validated for Brazil. RESULTS: scores showed that the levels of burnout in Army military who serve in the region are high. The main sociodemographic, labor, physical and social conditions that were associated with significantly higher levels of Burnout in this study were: reduced length of service, sedentary lifestyle, extra work, lower hierarchical rank and living away from relatives. CONCLUSION: the interaction between the two instruments found that the military working in the operational area, warrant officers, sergeants, between 6 and 10 years in service, single, who do little physical activity and whose relatives live far away were the ones who had the highest Burnout levels.


OBJETIVO: este estudio tuvo como objetivo investigar los niveles de agotamiento y posibles factores predisponentes entre los militares (oficiales y sargentos) del ejército brasileño que estaban sirviendo en la Amazonía brasileña. MÉTODO: la muestra consistió en 122 militares voluntarios con una edad promedio de 36.80 ± 6.69 años, 53 soldados fueron empleados en las misiones operativas (seguridad fronteriza, patrulla, ejercicios de defensa externa e interna) y 69 militares que fueron empleados en las misiones administrativas (logística interna). Se seleccionaron oficiales (29) y sargentos (93) que sirvieron en Porto Velho, en el noroeste de Brasil. Respondieron a un cuestionario sociodemográfico y al Maslach Burnout Inventory, validado para Brasil. RESULTADOS: los puntajes mostraron que los niveles de agotamiento en los militares del Ejército que sirven en la región son altos. Las principales condiciones sociodemográficas, laborales, físicas y sociales que se asociaron con niveles significativamente más altos de agotamiento en el presente estudio fueron: reducción de la duración del servicio, estilo de vida sedentario, trabajo extra, rango jerárquico más bajo y vivir lejos de los familiares. CONCLUSIÓN: la interacción entre los dos instrumentos encontró que los militares que trabajan en el área operativa, los suboficiales, los sargentos, entre 6 y 10 años en servicio, solteros, que realizan poca actividad física y cuyos familiares viven lejos fueron los que tenían el niveles de agotamiento más altos.


Assuntos
Humanos , Condições Sociais , Exercício Físico , Incidência , Causalidade , Ecossistema Amazônico , Esgotamento Psicológico , Militares , Categorias de Trabalhadores
13.
Medicina (Kaunas) ; 57(11)2021 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-34833462

RESUMO

SARS-CoV-2 neuroinvasive and neurotropic abilities may underlie delirium onset and neuropsychiatric outcomes. Only a limited number of studies have addressed the potential effect of SARS-CoV-2 infection on mental health so far. Most studies mainly reported the acute onset of mixed neuropsychiatric conditions in patients infected with SARS-CoV-2, characterized by agitated behavior, altered level of consciousness, and disorganized thinking, regardless of psychological or socioeconomic triggering factors. The present narrative review aims to analyze and discuss the mechanisms underlying the neuroinvasive/neurotropic properties of SARS-CoV-2 and the subsequent mental complications. Delirium appeared as a clinical manifestation of SARS-CoV-2 brain infection in some patients, without systemic or multiple organ failure symptoms. A small number of studies demonstrated that neuropsychiatric symptoms associated with COVID-19, initially presenting as a confused state, may subsequently evolve in a way that is consistent with the patients' neuropsychiatric history. A literature analysis on this topic prevalently showed case reports and case series of patients presenting delirium or delirium-like symptoms as the main outburst of COVID-19, plus a cognitive impairment, from mild to severe, which pre-existed or was demonstrated during the acute phase or after infection. Dementia appeared as one of the most frequent predisposing factors to SARS-CoV-2 infection complicated with delirium. Instead, contrasting data emerged on the potential link between COVID-19 and delirium in patients with cognitive impairment and without a neuropsychiatric history. Therefore, clinicians should contemplate the possibility that COVID-19 appears as delirium followed by a psychiatric exacerbation, even without other systemic symptoms. In addition, cognitive impairment might act as a predisposing factor for COVID-19 in patients with delirium.


Assuntos
COVID-19 , Disfunção Cognitiva , Delírio , Causalidade , Disfunção Cognitiva/etiologia , Delírio/etiologia , Humanos , SARS-CoV-2
14.
Artigo em Inglês | MEDLINE | ID: mdl-34769714

RESUMO

Beliefs about cause and effect, including health beliefs, are thought to be related to the frequency of the target outcome (e.g., health recovery) occurring when the putative cause is present and when it is absent (treatment administered vs. no treatment); this is known as contingency learning. However, it is unclear whether unvalidated health beliefs, where there is no evidence of cause-effect contingency, are also influenced by the subjective perception of a meaningful contingency between events. In a survey, respondents were asked to judge a range of health beliefs and estimate the probability of the target outcome occurring with and without the putative cause present. Overall, we found evidence that causal beliefs are related to perceived cause-effect contingency. Interestingly, beliefs that were not predicted by perceived contingency were meaningfully related to scores on the paranormal belief scale. These findings suggest heterogeneity in pseudoscientific health beliefs and the need to tailor intervention strategies according to underlying causes.


Assuntos
Inquéritos e Questionários , Causalidade , Probabilidade
15.
Pulm Med ; 2021: 4712406, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34765263

RESUMO

Periodontal diseases are a range of polymicrobial infectious disorders, such as gingivitis and periodontitis, which affect tooth-supporting tissues and are linked to playing a role in the exacerbation of several pulmonary diseases. Pulmonary diseases, such as pneumonia, chronic obstructive pulmonary disease (COPD), asthma, tuberculosis, COVID-19, and bronchiectasis, significantly contribute to poor quality of life and mortality. The association between periodontal disease and pulmonary outcomes is an important topic and requires further attention. Numerous resident microorganisms coexist in the oral cavity and lungs. However, changes in the normal microflora due to oral disease, old age, lifestyle habits, or dental intervention may contribute to altered aspiration of oral periodontopathic bacteria into the lungs and changing inflammatory responses. Equally, periodontal diseases are associated with the longitudinal decline in spirometry lung volume. Several studies suggest a possible beneficial effect of periodontal therapy in improving lung function with a decreased frequency of exacerbations and reduced risk of adverse respiratory events and morbidity. Here, we review the current literature outlining the link between the oral cavity and pulmonary outcomes and focus on the microflora of the oral cavity, environmental and genetic factors, and preexisting conditions that can impact oral and pulmonary outcomes.


Assuntos
Microbiota , Boca/microbiologia , Doenças Periodontais/complicações , Doença Pulmonar Obstrutiva Crônica/complicações , Causalidade , Meio Ambiente , Humanos
17.
MMW Fortschr Med ; 163(20): 10, 2021 Nov.
Artigo em Alemão | MEDLINE | ID: mdl-34767198
19.
Zhonghua Liu Xing Bing Xue Za Zhi ; 42(4): 735-739, 2021 Apr 10.
Artigo em Chinês | MEDLINE | ID: mdl-34814460

RESUMO

There are usually unknown or unmeasured confounders in the observational study, which is a significant challenge in epidemiological causal association research. This paper presents a tool for identification and effect assessment of unknown/unmeasured confounders in observational studies: probe variables. It can be divided into three forms: exposure probe variable, outcome probe variable, and mediation probe variable. The first two types can identify unknown/unmeasured confounding factors and estimate their size of effect to reveal the real correlation between exposure and outcome. The mediation probe variable controls for "mediating factors" to identify unmeasured confounders between exposure and results. The most significant difficulty in this theory's practice is selecting and determining "probe variables." Improper probe variables may introduce unknown confounders, which may lead to false identification of unmeasured confounders. Probe variables can be recommended as a sensitivity analysis in observational studies to help readers truly understand the association between exposure and outcomes and to increase the strength of evidence in observational epidemiological studies.


Assuntos
Fatores de Confusão Epidemiológicos , Viés , Causalidade , Estudos Epidemiológicos , Humanos
20.
Zhonghua Liu Xing Bing Xue Za Zhi ; 42(4): 740-744, 2021 Apr 10.
Artigo em Chinês | MEDLINE | ID: mdl-34814461

RESUMO

Matching is a standard method for selecting research objects regarding the observational research, which controls confounding factors and improves statistical efficiency. However, its role in controlling confounding is not consistent in different observational studies. Matching can eliminate the confounding bias of matching variables in cohort studies, but checking on itself cannot eliminate confounding bias in case-control studies. In matched case-control studies, researchers may not accurately judge whether the variable is a confounder. Sometimes the variables that are not confounders are mistakenly matched. In that case, it will result in overmatching, which will lead to the decline of statistical efficiency or the introduction of unavoidable bias or increase of workload. If the real confounding factors are omitted, it will cause confounding bias. Therefore, researchers should consider what kind of matching variable selection criteria should be formulated. A directed acyclic graph is a visual graphic language that can show the complicated causality among different epidemiological research designs. This article analyzes the role of Matching in different observational research designs from the perspective of the directed acyclic graph, formulates the selection criteria for matching variables in matched case-control studies, and provides some reference suggestions for future epidemiological research design.


Assuntos
Fatores de Confusão Epidemiológicos , Viés , Estudos de Casos e Controles , Causalidade , Estudos de Coortes , Humanos
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