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Tyler J Vanderweele - One of the best experts on this subject based on the ideXlab platform.
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invited commentary frontiers of power assessment in Mediation Analysis
American Journal of Epidemiology, 2020Co-Authors: Tyler J VanderweeleAbstract:The development of tools for power and sample-size calculations for Mediation Analysis has lagged far behind the development of methods. The accompanying paper by Rudolph et al. (Am J Epidemiol. 2020;189(12):1559-1567) is a helpful contribution in using simulations as a tool for power calculations for more complex methods and settings. Much work remains to be done in the development of easy-to-use packages and simple online websites for carrying out power and sample-size calculations for Mediation Analysis. Much remains to be learned with respect to the relative power of different methods in different settings. There will likely be feedback between these 2 important frontiers of the tools we have available and of our understanding of power when conducting Mediation Analysis.
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Mediation Analysis for a survival outcome with time varying exposures mediators and confounders
Statistics in Medicine, 2017Co-Authors: Shenghsuan Lin, Jessica G Young, Roger Logan, Tyler J VanderweeleAbstract:We propose an approach to conduct Mediation Analysis for survival data with time-varying exposures, mediators, and confounders. We identify certain interventional direct and indirect effects through a survival Mediational g-formula and describe the required assumptions. We also provide a feasible parametric approach along with an algorithm and software to estimate these effects. We apply this method to analyze the Framingham Heart Study data to investigate the causal mechanism of smoking on mortality through coronary artery disease. The estimated overall 10-year all-cause mortality risk difference comparing “always smoke 30 cigarettes per day” versus “never smoke” was 4.3 (95 % CI = (1.37, 6.30)). Of the overall effect, we estimated 7.91% (95% CI: = 1.36%, 19.32%) was mediated by the incidence and timing of coronary artery disease. The survival Mediational g-formula constitutes a powerful tool for conducting Mediation Analysis with longitudinal data.
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quantile causal Mediation Analysis allowing longitudinal data
Statistics in Medicine, 2017Co-Authors: Marieabele Bind, Joel Schwartz, Tyler J Vanderweele, Brent A CoullAbstract:Mediation Analysis has mostly been conducted with mean regression models. With this approach modeling means, formulae for direct and indirect effects are based on changes in means, which may not capture effects that occur in units at the tails of mediator and outcome distributions. Individuals with extreme values of medical endpoints are often more susceptible to disease and can be missed if one investigates mean changes only. We derive the controlled direct and indirect effects of an exposure along percentiles of the mediator and outcome using quantile regression models and a causal framework. The quantile regression models can accommodate an exposure-mediator interaction and random intercepts to allow for longitudinal mediator and outcome. Because DNA methylation acts as a complex “switch” to control gene expression and fibrinogen is a cardiovascular factor, individuals with extreme levels of these markers may be more susceptible to air pollution. We therefore apply this methodology to environmental data to estimate the effect of air pollution, as measured by particle number, on fibrinogen levels through a change in interferon-gamma (IFN-γ) methylation. We estimate the controlled direct effect of air pollution on the qth percentile of fibrinogen and its indirect effect through a change in the pth percentile of IFN-γ methylation. We found evidence of a direct effect of particle number on the upper tail of the fibrinogen distribution. We observed a suggestive indirect effect of particle number on the upper tail of the fibrinogen distribution through a change in the lower percentiles of the IFN-γ methylation distribution.
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Mediation Analysis with time varying exposures and mediators
Journal of The Royal Statistical Society Series B-statistical Methodology, 2017Co-Authors: Tyler J Vanderweele, Eric Tchetgen J TchetgenAbstract:In this paper we consider causal Mediation Analysis when exposures and mediators vary over time. We give non-parametric identification results, discuss parametric implementation, and also provide a weighting approach to direct and indirect effects based on combining the results of two marginal structural models. We also discuss how our results give rise to a causal interpretation of the effect estimates produced from longitudinal structural equation models. When there are time-varying confounders affected by prior exposure and mediator, natural direct and indirect effects are not identified. However, we define a randomized interventional analogue of natural direct and indirect effects that are identified in this setting. The formula that identifies these effects we refer to as the "Mediational g-formula." When there is no Mediation, the Mediational g-formula reduces to Robins' regular g-formula for longitudinal data. When there are no time-varying confounders affected by prior exposure and mediator values, then the Mediational g-formula reduces to a longitudinal version of Pearl's Mediation formula. However, the Mediational g-formula itself can accommodate both Mediation and time-varying confounders and constitutes a general approach to Mediation Analysis with time-varying exposures and mediators.
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parametric Mediational g formula approach to Mediation Analysis with time varying exposures mediators and confounders
Epidemiology, 2017Co-Authors: Shenghsuan Lin, Eric Tchetgen J Tchetgen, Jessica G Young, Roger Logan, Tyler J VanderweeleAbstract:The assessment of direct and indirect effects with time-varying mediators and confounders is a common but challenging problem, and standard Mediation Analysis approaches are generally not applicable in this context. The Mediational g-formula was recently proposed to address this problem, paired with
Seung Sup Kim - One of the best experts on this subject based on the ideXlab platform.
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role of ses on the association between childhood parental death and adulthood suicidal ideation a Mediation Analysis using longitudinal dataset in south korea
BMC Psychiatry, 2021Co-Authors: Jaehong Yoon, Ja Young Kim, Ji Hwan Kim, Seung Sup KimAbstract:Background We sought to examine the association between childhood experience of parental death (CEPD) and adulthood suicidal ideation, and the mediating role of adulthood SES in the association. Methods We analyzed a nationally representative dataset of 8609 adults from the Korea Welfare Panel Study, which is a longitudinal cohort dataset in South Korea. CEPD was measured using a question: "During your childhood (0-17 years old), have you experienced the death of parents?" We classified responses of CEPD during 2006-2011 into 'yes,' and the others into 'no.' Suicidal ideation over the past year was assessed annually during 2012-2019. As a potential mediator, adulthood educational attainment and household income in 2011 were included in the Analysis. Logistic regression was applied to examine the association of CEPD with adulthood suicidal ideation across age groups (early adulthood, 19-39 years old; middle adulthood, 40-59 years old; late adulthood, ≥60 years old), after excluding people who reported lifetime suicidal ideation in 2011. Causal Mediation Analysis using a parametric regression model was applied to examine the mediating role of adulthood SES in the association between CEPD and adulthood suicidal ideation. Results After adjusting for potential confounders including childhood SES, CEPD was significantly associated with adulthood suicidal ideation among the late adulthood group (OR: 1.43; 95% CI: 1.13-1.81), while the association was not statistically significant among the early; and middle adulthood groups. In Mediation Analysis of adulthood household income, both indirect association (ORNIE: 1.05; 95% CI: 1.02-1.09) and direct association (ORNDE: 1.37; 95% CI: 1.09-1.73) were statistically significant among the late adulthood group. In the Mediation Analysis of adulthood education attainment among the late adulthood, only a direct association was statistically significant (ORNDE: 1.43; 95% CI: 1.14-1.80). Conclusions These results suggest that CEPD could be a risk factor for adulthood suicidal ideation. Furthermore, the findings imply that income security policy might be necessary to reduce suicide among the late adulthood group.
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role of ses on the association between childhood parental death and adulthood suicidal ideation a Mediation Analysis using longitudinal dataset in south korea
BMC Psychiatry, 2021Co-Authors: Jaehong Yoon, Ja Young Kim, Ji Hwan Kim, Seung Sup KimAbstract:We sought to examine the association between childhood experience of parental death (CEPD) and adulthood suicidal ideation, and the mediating role of adulthood SES in the association. We analyzed a nationally representative dataset of 8609 adults from the Korea Welfare Panel Study, which is a longitudinal cohort dataset in South Korea. CEPD was measured using a question: “During your childhood (0-17 years old), have you experienced the death of parents?” We classified responses of CEPD during 2006–2011 into ‘yes,’ and the others into ‘no.’ Suicidal ideation over the past year was assessed annually during 2012–2019. As a potential mediator, adulthood educational attainment and household income in 2011 were included in the Analysis. Logistic regression was applied to examine the association of CEPD with adulthood suicidal ideation across age groups (early adulthood, 19–39 years old; middle adulthood, 40–59 years old; late adulthood, ≥60 years old), after excluding people who reported lifetime suicidal ideation in 2011. Causal Mediation Analysis using a parametric regression model was applied to examine the mediating role of adulthood SES in the association between CEPD and adulthood suicidal ideation. After adjusting for potential confounders including childhood SES, CEPD was significantly associated with adulthood suicidal ideation among the late adulthood group (OR: 1.43; 95% CI: 1.13–1.81), while the association was not statistically significant among the early; and middle adulthood groups. In Mediation Analysis of adulthood household income, both indirect association (ORNIE: 1.05; 95% CI: 1.02–1.09) and direct association (ORNDE: 1.37; 95% CI: 1.09–1.73) were statistically significant among the late adulthood group. In the Mediation Analysis of adulthood education attainment among the late adulthood, only a direct association was statistically significant (ORNDE: 1.43; 95% CI: 1.14–1.80). These results suggest that CEPD could be a risk factor for adulthood suicidal ideation. Furthermore, the findings imply that income security policy might be necessary to reduce suicide among the late adulthood group.
Eric Tchetgen J Tchetgen - One of the best experts on this subject based on the ideXlab platform.
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Mediation Analysis for censored survival data under an accelerated failure time model
Epidemiology, 2017Co-Authors: Isabel R Fulcher, Eric Tchetgen J Tchetgen, Paige L WilliamsAbstract:: Recent advances in causal Mediation Analysis have formalized conditions for estimating direct and indirect effects in various contexts. These approaches have been extended to a number of models for survival outcomes including accelerated failure time models, which are widely used in a broad range of health applications given their intuitive interpretation. In this setting, it has been suggested that under standard assumptions, the "difference" and "product" methods produce equivalent estimates of the indirect effect of exposure on the survival outcome. We formally show that these two methods may produce substantially different estimates in the presence of censoring or truncation, due to a form of model misspecification. Specifically, we establish that while the product method remains valid under standard assumptions in the presence of independent censoring, the difference method can be biased in the presence of such censoring whenever the error distribution of the accelerated failure time model fails to be collapsible upon marginalizing over the mediator. This will invariably be the case for most choices of mediator and outcome error distributions. A notable exception arises in case of normal mediator-normal outcome where we show consistency of both difference and product estimators in the presence of independent censoring. These results are confirmed in simulation studies and two data applications.
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Mediation Analysis with time varying exposures and mediators
Journal of The Royal Statistical Society Series B-statistical Methodology, 2017Co-Authors: Tyler J Vanderweele, Eric Tchetgen J TchetgenAbstract:In this paper we consider causal Mediation Analysis when exposures and mediators vary over time. We give non-parametric identification results, discuss parametric implementation, and also provide a weighting approach to direct and indirect effects based on combining the results of two marginal structural models. We also discuss how our results give rise to a causal interpretation of the effect estimates produced from longitudinal structural equation models. When there are time-varying confounders affected by prior exposure and mediator, natural direct and indirect effects are not identified. However, we define a randomized interventional analogue of natural direct and indirect effects that are identified in this setting. The formula that identifies these effects we refer to as the "Mediational g-formula." When there is no Mediation, the Mediational g-formula reduces to Robins' regular g-formula for longitudinal data. When there are no time-varying confounders affected by prior exposure and mediator values, then the Mediational g-formula reduces to a longitudinal version of Pearl's Mediation formula. However, the Mediational g-formula itself can accommodate both Mediation and time-varying confounders and constitutes a general approach to Mediation Analysis with time-varying exposures and mediators.
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parametric Mediational g formula approach to Mediation Analysis with time varying exposures mediators and confounders
Epidemiology, 2017Co-Authors: Shenghsuan Lin, Eric Tchetgen J Tchetgen, Jessica G Young, Roger Logan, Tyler J VanderweeleAbstract:The assessment of direct and indirect effects with time-varying mediators and confounders is a common but challenging problem, and standard Mediation Analysis approaches are generally not applicable in this context. The Mediational g-formula was recently proposed to address this problem, paired with
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Mediation Analysis for censored survival data under an accelerated failure time model
arXiv: Methodology, 2016Co-Authors: Isabel R Fulcher, Eric Tchetgen J Tchetgen, Paige L WilliamsAbstract:Recent advances in causal Mediation Analysis have formalized conditions for estimating direct and indirect effects in various contexts. These approaches have been extended to a number of models for survival outcomes including accelerated failure time (AFT) models which are widely used in a broad range of health applications given their intuitive interpretation. In this setting, it has been suggested that under standard assumptions, the "difference" and "product" methods produce equivalent estimates of the indirect effect of exposure on the survival outcome. We formally show that these two methods may produce substantially different estimates in the presence of censoring or truncation, due to a form of model misspecification. Specifically, we establish that while the product method remains valid under standard assumptions in the presence of independent censoring, the difference method can be biased in the presence of such censoring whenever the error distribution of the AFT model fails to be collapsible upon marginalizing over the mediator. This will invariably be the case for most choices of mediator and outcome error distributions. A notable exception arises in case of normal mediator-normal outcome where we show consistency of both difference and product estimators in the presence of independent censoring. These results are confirmed in simulation studies and two data applications.
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inverse odds ratio weighted estimation for causal Mediation Analysis
Statistics in Medicine, 2013Co-Authors: Eric Tchetgen J TchetgenAbstract:An important scientific goal of studies in the health and social sciences is increasingly to determine to what extent the total effect of a point exposure is mediated by an intermediate variable on the causal pathway between the exposure and the outcome. A causal framework has recently been proposed for Mediation Analysis, which gives rise to new definitions, formal identification results and novel estimators of direct and indirect effects. In the present paper, the author describes a new inverse odds ratio-weighted (IORW) approach to estimate so-called natural direct and indirect effects. The approach which uses as a weight, the inverse of an estimate of the odds ratio function relating the exposure and the mediator is universal in that it can be used to decompose total effects in a number of regression models commonly used in practice. Specifically, the approach may be used for effect decomposition in generalized linear models with a nonlinear link function, and in a number of other commonly used models such as the Cox proportional hazards regression for a survival outcome. The approach is simple and can be implemented in standard software provided a weight can be specified for each observation. An additional advantage of the method is that it easily incorporates multiple mediators of a categorical, discrete or continuous nature.
Ken Osaka - One of the best experts on this subject based on the ideXlab platform.
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cohort study on laryngeal cough reflex respiratory disease and death a Mediation Analysis
Journal of the American Medical Directors Association, 2019Co-Authors: Takafumi Yamamoto, Toru Tsuboya, Kemmyo Sugiyama, Tatsuo Yamamoto, Jun Aida, Katsunori Kondo, Tomohiro Shinozaki, Keiichi Sasaki, Ken OsakaAbstract:Abstract Objective To estimate quantitatively whether the presence of cough associated with dysphagia (laryngeal cough reflex) increased mortality through respiratory disease among community-dwelling older Japanese. Design A 6-year follow-up prospective cohort study (from 2010 to 2017). Setting Thirteen municipalities in Japan. Participants Community-dwelling individuals aged 65 years or older (N = 32,682). Measures The baseline survey was conducted through self-reported questionnaire. Exposure was experience of laryngeal cough reflex while drinking. The outcome was all-cause mortality. All covariates were selected from demographic, socioeconomic variables, baseline health and functional status, smoking, alcohol drinking, number of remaining teeth, and stroke. The mediator variable was respiratory disease. Cox proportional hazards regression was used to estimate hazard ratios (HRs) for mortality. Parametric Mediation Analysis was conducted to estimate the effect of laryngeal cough reflex on the mean residual time to death mediated through respiratory disease. Results Among the 32,682 participants (mean age = 74.1 years, standard deviation = 5.9 years), 5550 (17.0%) experienced laryngeal cough reflex at baseline. A total of 4037 deaths occurred. Crude mortality rates of the participants with or without laryngeal cough reflex were 16.3% and 11.6%, respectively. After adjusting for covariates, laryngeal cough reflex [HR = 1.10; 95% confidence interval (CI) = 1.02 to 1.19] and respiratory disease (HR = 1.80; 95% CI = 1.62 to 2.00) were associated with mortality. The Mediation Analysis showed that respiratory disease significantly (P Conclusions/Implications Laryngeal cough reflex was a prevalent condition, and it was associated with all-cause mortality in community-dwelling older Japanese individuals. Clinicians could contribute to reduce mortality risk by addressing swallowing function problems using their interprofessional collaboration team (speech-language pathologist, dentist, rehabilitation doctor, otolaryngologist, respiratory physician, and gerontologist).
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cohort study on laryngeal cough reflex respiratory disease and death a Mediation Analysis
Journal of the American Medical Directors Association, 2019Co-Authors: Takafumi Yamamoto, Toru Tsuboya, Kemmyo Sugiyama, Tatsuo Yamamoto, Jun Aida, Katsunori Kondo, Tomohiro Shinozaki, Keiichi Sasaki, Ken OsakaAbstract:Abstract Objective To estimate quantitatively whether the presence of cough associated with dysphagia (laryngeal cough reflex) increased mortality through respiratory disease among community-dwelling older Japanese. Design A 6-year follow-up prospective cohort study (from 2010 to 2017). Setting Thirteen municipalities in Japan. Participants Community-dwelling individuals aged 65 years or older (N = 32,682). Measures The baseline survey was conducted through self-reported questionnaire. Exposure was experience of laryngeal cough reflex while drinking. The outcome was all-cause mortality. All covariates were selected from demographic, socioeconomic variables, baseline health and functional status, smoking, alcohol drinking, number of remaining teeth, and stroke. The mediator variable was respiratory disease. Cox proportional hazards regression was used to estimate hazard ratios (HRs) for mortality. Parametric Mediation Analysis was conducted to estimate the effect of laryngeal cough reflex on the mean residual time to death mediated through respiratory disease. Results Among the 32,682 participants (mean age = 74.1 years, standard deviation = 5.9 years), 5550 (17.0%) experienced laryngeal cough reflex at baseline. A total of 4037 deaths occurred. Crude mortality rates of the participants with or without laryngeal cough reflex were 16.3% and 11.6%, respectively. After adjusting for covariates, laryngeal cough reflex [HR = 1.10; 95% confidence interval (CI) = 1.02 to 1.19] and respiratory disease (HR = 1.80; 95% CI = 1.62 to 2.00) were associated with mortality. The Mediation Analysis showed that respiratory disease significantly (P Conclusions/Implications Laryngeal cough reflex was a prevalent condition, and it was associated with all-cause mortality in community-dwelling older Japanese individuals. Clinicians could contribute to reduce mortality risk by addressing swallowing function problems using their interprofessional collaboration team (speech-language pathologist, dentist, rehabilitation doctor, otolaryngologist, respiratory physician, and gerontologist).
Takafumi Yamamoto - One of the best experts on this subject based on the ideXlab platform.
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cohort study on laryngeal cough reflex respiratory disease and death a Mediation Analysis
Journal of the American Medical Directors Association, 2019Co-Authors: Takafumi Yamamoto, Toru Tsuboya, Kemmyo Sugiyama, Tatsuo Yamamoto, Jun Aida, Katsunori Kondo, Tomohiro Shinozaki, Keiichi Sasaki, Ken OsakaAbstract:Abstract Objective To estimate quantitatively whether the presence of cough associated with dysphagia (laryngeal cough reflex) increased mortality through respiratory disease among community-dwelling older Japanese. Design A 6-year follow-up prospective cohort study (from 2010 to 2017). Setting Thirteen municipalities in Japan. Participants Community-dwelling individuals aged 65 years or older (N = 32,682). Measures The baseline survey was conducted through self-reported questionnaire. Exposure was experience of laryngeal cough reflex while drinking. The outcome was all-cause mortality. All covariates were selected from demographic, socioeconomic variables, baseline health and functional status, smoking, alcohol drinking, number of remaining teeth, and stroke. The mediator variable was respiratory disease. Cox proportional hazards regression was used to estimate hazard ratios (HRs) for mortality. Parametric Mediation Analysis was conducted to estimate the effect of laryngeal cough reflex on the mean residual time to death mediated through respiratory disease. Results Among the 32,682 participants (mean age = 74.1 years, standard deviation = 5.9 years), 5550 (17.0%) experienced laryngeal cough reflex at baseline. A total of 4037 deaths occurred. Crude mortality rates of the participants with or without laryngeal cough reflex were 16.3% and 11.6%, respectively. After adjusting for covariates, laryngeal cough reflex [HR = 1.10; 95% confidence interval (CI) = 1.02 to 1.19] and respiratory disease (HR = 1.80; 95% CI = 1.62 to 2.00) were associated with mortality. The Mediation Analysis showed that respiratory disease significantly (P Conclusions/Implications Laryngeal cough reflex was a prevalent condition, and it was associated with all-cause mortality in community-dwelling older Japanese individuals. Clinicians could contribute to reduce mortality risk by addressing swallowing function problems using their interprofessional collaboration team (speech-language pathologist, dentist, rehabilitation doctor, otolaryngologist, respiratory physician, and gerontologist).
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cohort study on laryngeal cough reflex respiratory disease and death a Mediation Analysis
Journal of the American Medical Directors Association, 2019Co-Authors: Takafumi Yamamoto, Toru Tsuboya, Kemmyo Sugiyama, Tatsuo Yamamoto, Jun Aida, Katsunori Kondo, Tomohiro Shinozaki, Keiichi Sasaki, Ken OsakaAbstract:Abstract Objective To estimate quantitatively whether the presence of cough associated with dysphagia (laryngeal cough reflex) increased mortality through respiratory disease among community-dwelling older Japanese. Design A 6-year follow-up prospective cohort study (from 2010 to 2017). Setting Thirteen municipalities in Japan. Participants Community-dwelling individuals aged 65 years or older (N = 32,682). Measures The baseline survey was conducted through self-reported questionnaire. Exposure was experience of laryngeal cough reflex while drinking. The outcome was all-cause mortality. All covariates were selected from demographic, socioeconomic variables, baseline health and functional status, smoking, alcohol drinking, number of remaining teeth, and stroke. The mediator variable was respiratory disease. Cox proportional hazards regression was used to estimate hazard ratios (HRs) for mortality. Parametric Mediation Analysis was conducted to estimate the effect of laryngeal cough reflex on the mean residual time to death mediated through respiratory disease. Results Among the 32,682 participants (mean age = 74.1 years, standard deviation = 5.9 years), 5550 (17.0%) experienced laryngeal cough reflex at baseline. A total of 4037 deaths occurred. Crude mortality rates of the participants with or without laryngeal cough reflex were 16.3% and 11.6%, respectively. After adjusting for covariates, laryngeal cough reflex [HR = 1.10; 95% confidence interval (CI) = 1.02 to 1.19] and respiratory disease (HR = 1.80; 95% CI = 1.62 to 2.00) were associated with mortality. The Mediation Analysis showed that respiratory disease significantly (P Conclusions/Implications Laryngeal cough reflex was a prevalent condition, and it was associated with all-cause mortality in community-dwelling older Japanese individuals. Clinicians could contribute to reduce mortality risk by addressing swallowing function problems using their interprofessional collaboration team (speech-language pathologist, dentist, rehabilitation doctor, otolaryngologist, respiratory physician, and gerontologist).