Cited by 356Advanced Causal Inference TechniquesStatistical Methods in Clinical TrialsMeta-analysis and systematic reviews

Mediation and moderation of treatment effects in randomised controlled trials of complex interventions

Emsley, Richard, Dunn, Graham, White, Ian R·2010·Statistical Methods in Medical Research

Abstract

Complex intervention trials should be able to answer both pragmatic and explanatory questions in order to test the theories motivating the intervention and help understand the underlying nature of the clinical problem being tested. Key to this is the estimation of direct effects of treatment and indirect effects acting through intermediate variables which are measured post-randomisation. Using psychological treatment trials as an example of complex interventions, we review statistical methods which crucially evaluate both direct and indirect effects in the presence of hidden confounding between mediator and outcome. We review the historical literature on mediation and moderation of treatment effects. We introduce two methods from within the existing causal inference literature, principal stratification and structural mean models, and demonstrate how these can be applied in a mediation context before discussing approaches and assumptions necessary for attaining identifiability of key parameters of the basic causal model. Assuming that there is modification by baseline covariates of the effect of treatment (i.e. randomisation) on the mediator (i.e. covariate by treatment interactions), but no direct effect on the outcome of these treatment by covariate interactions leads to the use of instrumental variable methods. We describe how moderation can occur through post-randomisation variables, and extend the principal stratification approach to multiple group methods with explanatory models nested within the principal strata. We illustrate the new methodology with motivating examples of randomised trials from the mental health literature.

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Crossref · 10.1177/0962280209105014

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Authors
Emsley, R., Dunn, G., & White, I. R.
Affiliations
  • University of Manchester (GB)
  • MRC Biostatistics Unit (GB)
Corresponding author
Dunn, Graham
Venue
Statistical Methods in Medical Research
Published
2009-07-16
Volume
19
Issue
3
Pages
237-270
ISSN
  • 0962-2802 (ISSN-L)
  • 1477-0334
OpenAlex
W2092884989
Cited by
356
References
115
Citations by year
2026: 7 · 2025: 9 · 2024: 10 · 2023: 13 · 2022: 12 · 2021: 28 · 2020: 17 · 2019: 30 · 2018: 23 · 2017: 34 · 2016: 38 · 2015: 33 · 2014: 25 · 2013: 34 · 2012: 20
FWCI
11.62
Type
journal article
Language
en
Open access
closed
Locations
  • Statistical Methods in Medical Research (publishedVersion)
  • PubMed (publishedVersion)
  • Research Portal (King's College London) (submittedVersion)
  • Research Explorer (The University of Manchester) (submittedVersion)
Funders
Medical Research Council
Topics
  • Physical Sciences › Mathematics › Statistics and Probability › Advanced Causal Inference Techniques
  • Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Clinical Trials
  • Social Sciences › Decision Sciences › Statistics, Probability and Uncertainty › Meta-analysis and systematic reviews
Keywords
mediation analysis, moderation analysis, complex interventions, unmeasured confounding, principal stratification, instrumental variables, mental health interventions, causal inference
MeSH terms
Suicide Prevention, Depression, Humans, Mental Health, Psychotherapy, Schizophrenia, Models, Statistical, Randomized Controlled Trials as Topic, Treatment Outcome, Outcome Assessment, Health Care, Risk Reduction Behavior, Biostatistics

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