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Activity Number:
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645
- Causal Mediation Analysis in Advanced Settings: Longitudinal, High-Dimensional, Censored Mediations
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Type:
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Topic Contributed
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Date/Time:
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Thursday, August 3, 2017 : 10:30 AM to 12:20 PM
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Sponsor:
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Mental Health Statistics Section
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Abstract #322785
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View Presentation
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Title:
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Explaining the Total Effect in the Presence of Multiple Mediators and Interactions
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Author(s):
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Linda Valeri* and Andrea Bellavia
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Companies:
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Harvard University and Harvard T.H. Chan School of Public Health
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Keywords:
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effect decomposition ;
interaction ;
mediation ;
antipsychotics ;
schizophrenia
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Abstract:
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Mediation analysis allows decomposing a total effect into a direct effect of the exposure on the outcome and an indirect effect operating through a number of possible hypothesized pathways. A recent study has provided formal definitions of direct and indirect effects when multiple mediators are of interested. Parametric and semi-parametric methods to estimate path-specific effects have also been described. Investigating direct and indirect effects with multiple mediators can be challenging in the presence of multiple exposure-mediator and mediator-mediator interactions. Our study provides three main contributions: 1) we obtain counterfactual definitions of interaction terms when more than one mediator is present; 2) we derive a decomposition of the total effect that unifies mediation and interaction when multiple mediators are present; and 3) we illustrate the connection between our decomposition and the 4-way decomposition of the total effect introduced in the context of a single mediator. We employ the decomposition to investigate the interplay of adverse events and psychiatric symptoms in explaining the effect of antipsychotics on social functioning in schizophrenia patients.
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Authors who are presenting talks have a * after their name.
