Abstract
In randomized trials, the primary analysis is usually based on an intention-to-treat approach which answers the question “What is the effect of offering treatment?” There are many other questions that investigators could pose such as “Does this treatment work if it is received?” “What factors make the treatment work better?” and “How does the treatment work?” These questions require alternative analysis approaches based on statistical methods drawn from the causal inference literature, including instrumental variables and causal mediation analysis. This chapter will define relevant causal estimands and describe methods that can be used to estimate them, their underlying assumptions, and the estimation procedures. The methods will be illustrated using examples drawn from the literature.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
References
Albert JM, Nelson S (2011) Generalized causal mediation analysis. Biometrics 67:1028–1038
Angrist JD, Imbens GW, Rubin DB (1996) Identification of causal effects using instrumental variables. J Am Stat Assoc 91:444–455
Burgess S, Davies NM, Thompson SG, E. PIC-InterAct Consortium (2014) Instrumental variable analysis with a nonlinear exposure-outcome relationship. Epidemiology 25:877–885
Burgess S, Small DS, Thompson SG (2017) A review of instrumental variable estimators for Mendelian randomization. Stat Methods Med Res 26:2333–2355
Clarke PS, Windmeijer F (2012) Instrumental variable estimators for binary outcomes. J Am Stat Assoc 107:1638–1652
Daniel RM, De Stavola BL, Cousens SN, Vansteelandt S (2015) Causal mediation analysis with multiple mediators. Biometrics 71:1–14
Dodd S, White IR, Williamson P (2017a) A framework for the design, conduct and interpretation of randomised controlled trials in the presence of treatment changes. Trials 18
Dodd S, Williamson P, White IR (2017b) Adjustment for treatment changes in epilepsy trials: a comparison of causal methods for time-to-event outcomes. Stat Methods Med Res 0:1–17
Dowrick C, Dunn G, Ayuso-Mateos JL, Dalgard OS, Page H, Lehtinen V, Casey P, Wilkinson C, Vazquez-Barquero JL, Wilkinson G, Grp O (2000) Problem solving treatment and group psychoeducation for depression: multicentre randomised controlled trial. Br Med J 321:1450–1454
Dunn G, Bentall R (2007) Modelling treatment-effect heterogeneity in randomized controlled trials of complex interventions (psychological treatments). Stat Med 26:4719–4745
Dunn G, Maracy M, Dowrick C, Ayuso-Mateos JL, Dalgard OS, Page H, Lehtinen V, Casey P, Wilkinson C, Vazquez-Barquero JL, Wilkinson G, Grp O (2003) Estimating psychological treatment effects from a randomised controlled trial with both non-compliance and loss to follow-up. Br J Psychiatry 183:323–331
Dunn G, Emsley R, Liu HH, Landau S (2013) Integrating biomarker information within trials to evaluate treatment mechanisms and efficacy for personalised medicine. Clin Trials 10:709–719
Dunn G, Emsley R, Liu HH, Landau S, Green J, White I, Pickles A (2015) Evaluation and validation of social and psychological markers in randomised trials of complex interventions in mental health: a methodological research programme. Health Technol Assess 19
EMA (2017) ICH E9 (R1) addendum on estimands and sensitivity analysis in clinical trials to the guideline on statistical principles for clinical trials. In: European Medicines Agency
Emsley R, Dunn G, White IR (2010) Mediation and moderation of treatment effects in randomised controlled trials of complex interventions. Stat Methods Med Res 19:237–270
Fischer-Lapp K, Goetghebeur E (1999) Practical properties of some structural mean analyses of the effect of compliance in randomized trials. Control Clin Trials 20:531–546
Frangakis CE, Rubin DB (2002) Principal stratification in causal inference. Biometrics 58:21–29
Freeman D, Sheaves B, Goodwin GM, Yu LM, Harrison PJ, Emsley R, Bostock S, Foster RG, Wadekar V, Hinds C, Espie CA (2015) Effects of cognitive behavioural therapy for insomnia on the mental health of university students: study protocol for a randomized controlled trial. Trials 16(8)
Freeman D, Sheaves B, Goodwin GM, Yu LM, Nickless A, Harrison PJ, Emsley R, Luik AI, Foster RG, Wadekar V, Hinds C, Gumley A, Jones R, Lightman S, Jones S, Bentall R, Kinderman P, Rowse G, Brugha T, Blagrove M, Gregory AM, Fleming L, Walklet E, Glazebrook C, Davies EB, Hollis C, Haddock G, John B, Coulson M, Fowler D, Pugh K, Cape J, Moseley P, Brown G, Hughes C, Obonsawin M, Coker S, Watkins E, Schwannauer M, MacMahon K, Siriwardena AN, Espie CA (2017) The effects of improving sleep on mental health (OASIS): a randomised controlled trial with mediation analysis. Lancet Psychiatry 4:749–758
Ginestet CE, Emsley R, Landau S (2017) Dose-response modeling in mental health using stein-like estimators with instrumental variables. Stat Med 36:1696–1714
Ginestet CE, Emsley R, Landau S (2020) Stein-like estimators for causal mediation analysis in randomized trials. Stat Methods Med Res 29:1129–1148
Goldsmith LP, Lewis SW, Dunn G, Bentall RP (2015) Psychological treatments for early psychosis can be beneficial or harmful, depending on the therapeutic alliance: an instrumental variable analysis. Psychol Med 45:2365–2373
Goldsmith KA, Chalder T, White PD, Sharpe M, Pickles A (2018a) Measurement error, time lag, unmeasured confounding: considerations for longitudinal estimation of the effect of a mediator in randomised clinical trials. Stat Methods Med Res 27:1615–1633
Goldsmith KA, MacKinnon DP, Chalder T, White PD, Sharpe M, Pickles A (2018b) Tutorial: the practical application of longitudinal structural equation mediation models in clinical trials. Psychol Methods 23:191–207
Landau S, Emsley R, Dunn G (2018) Beyond total treatment effects in randomised controlled trials: baseline measurement of intermediate outcomes needed to reduce confounding in mediation investigations. Clin Trials 15:247–256
Maracy M, Dunn G (2011) Estimating dose-response effects in psychological treatment trials: the role of instrumental variables. Stat Methods Med Res 20:191–215
McCandless LC, Somers JM (n.d.) Bayesian sensitivity analysis for unmeasured confounding in causal mediation analysis. Stat Methods Med Res 0:0962280217729844
Padian NS, van der Straten A, Ramjee G, Chipato T, de Bruyn G, Blanchard K, Shiboski S, Montgomery ET, Fancher H, Cheng H, Rosenblum M, van der Laan M, Jewell N, McIntyre J, Team M (2007) Diaphragm and lubricant gel for prevention of HIV acquisition in southern African women: a randomised controlled trial. Lancet 370:251–261
Pickles A, Croudace T (2010) Latent mixture models for multivariate and longitudinal outcomes. Stat Methods Med Res 19:271–289
Pickles A, Harris V, Green J, Aldred C, McConachie H, Slonims V, Le Couteur A, Hudry K, Charman T, PACT Consortium (2015) Treatment mechanism in the MRC preschool autism communication trial: implications for study design and parent- focussed therapy for children. J Child Psychol Psychiatry 56:162–170
Robins JM, Greenland S (1992) Identifiability and exchangeability for direct adn indirect effects. Epidemiology 3:143–155
Rosenblum M, Jewell NP, van der Laan M, Shiboski S, van der Straten A, Padian N (2009) Analysing direct effects in randomized trials with secondary interventions: an application to human immunodeficiency virus prevention trials. J R Stat SocA Stat Soc 172:443–465
Rubin DB (1974) Estimating causal effects of treatmets in randomized and nonrandomized studies. J Educ Psychol 66:688–701
Sharples L, Papachristofi O, Rex S, Landau S (2020) Exploring mechanisms of action in trials of complex surgical interventions using mediation. Clin Trials. in press
Sheiner LB, Rubin DB (1995) Intention-to-treat analysis and goals of clinical trials. Clin Pharmacol Ther 57:6–15
Tarrier N, Lewis S, Haddock G, Bentall R, Drake R, Kinderman P, Kingdon D, Siddle R, Everitt J, Leadley K, Benn A, Grazebrook K, Haley C, Akhtar S, Davies L, Palmer S, Dunn G (2004) Cognitive-behavioural therapy in first-episode and early schizophrenia – 18-month follow-up of a randomised controlled trial. Br J Psychiatry 184:231–239
Tchetgen EJT, Walter S, Vansteelandt S, Martinussen T, Glymour M (2015) Instrumental variable estimation in a survival context. Epidemiol 26:402–410
Valeri L, VanderWeele TJ (2013) Mediation analysis allowing for exposure-mediator interactions and causal interpretation: theoretical assumptions and implementation with SAS and SPSS macros. Psychol Methods 18:137–150
VanderWeele TJ (2015) Explanation in causal inference: methods for mediation and interaction. Chapman Hall CRC, New York
VanderWeele TJ, Vansteelandt S (2009) Conceptual issues concerning mediation, interventions and composition. Stat Interface 2:457–468
Vansteelandt S, Daniel RM (2017) Interventional effects for mediation analysis with multiple mediators. Epidemiology 28:258–265
Wooldridge JM (2010) Econometric analysis of cross section and panel data. MIT Press
Acknowledgments
This work was supported by a grant from the UK Medical Research Council (MRC) (project Grants MR/K006185/1). R.E. was further supported by the MRC North West Hub for Trials Methodology Research (MR/K025635/1). S.L. and R.E are part-funded by the National Institute for Health Research (NIHR) Biomedical Research Centre at South London and Maudsley NHS Foundation Trust and King’s College London. S.L. is also supported by the NIHR Applied Research Collaboration South London (NIHR ARC South London) at King’s College Hospital NHS Foundation Trust. The views expressed are those of the authors and not necessarily those of the NIHR or the Department of Health and Social Care.
The work described here is the result of many years of collaborative research. The authors would like to thank Cedric Ginestet, Kim Goldsmith, Andrew Pickles, and Ian White for their contributions and suggestions. The authors dedicate this chapter to their late friend, colleague and mentor Graham Dunn, with whom these ideas were developed through many years of work.
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Section Editor information
Rights and permissions
Copyright information
© 2022 Springer Nature Switzerland AG
About this entry
Cite this entry
Landau, S., Emsley, R. (2022). Causal Inference: Efficacy and Mechanism Evaluation. In: Piantadosi, S., Meinert, C.L. (eds) Principles and Practice of Clinical Trials. Springer, Cham. https://doi.org/10.1007/978-3-319-52636-2_137
Download citation
DOI: https://doi.org/10.1007/978-3-319-52636-2_137
Published:
Publisher Name: Springer, Cham
Print ISBN: 978-3-319-52635-5
Online ISBN: 978-3-319-52636-2
eBook Packages: Mathematics and StatisticsReference Module Computer Science and Engineering