Biostatistics Group Seminar Series
Research Institute for Primary Care and Health Sciences
Keele University
Title: Estimating causal effects of time-varying exposures using
observational data: What can we do using standard regression methods.
Speaker: Dr Ruth Keogh, Department of Medical Statistics, London School
of Hygiene & Tropical Medicine.
Date: Thursday 17th January 12:00-13:00
Venue: Dinwoodie Lecture Theatre, David Weatherall Building
https://www.keele.ac.uk/connect/howtofindus/maps/keele-campus-guide-colour.pdf
Abstract: This talk will focus on estimation of causal effects from
observational studies with longitudinal repeated measures of exposures
and outcomes, such as when individuals are observed at repeated visits,
which is a common problem in epidemiology. Interest may lie in studying
the ‘total effect’ of an exposure at a given time on a concurrent or
subsequent outcome, or the effect of a pattern of exposures over time on
a subsequent outcome. It is sometimes not appreciated that standard
regression methods can be used, even in the presence of time-dependent
confounding, to estimate the total effect of an exposure on a subsequent
outcome by controlling appropriately for prior exposures, outcomes and
time-varying covariates. I will discuss the important considerations for
estimating causal total exposure effects using standard methods, and
make comparisons with alternative approaches from the causal inference
literature, in particular using marginal structural models fitted by
inverse probability weighting. I will give an example in which we have
used patient registry data to study the causal effect of a treatment
used in cystic fibrosis on lung function.
The talk will be partly based on recent work in the paper:
Keogh, Daniel, VanderWeele, Vansteelandt. Analysis of longitudinal
studies with repeated outcome measures: adjusting for time-dependent
confounding using conventional methods. Am J Epidemiol 2017;
https://doi.org/10.1093/aje/kwx311.
Forthcoming seminar: Dr Hayles Jones, Bristol University, Thursday 14th
March 13:00-14:00, Title TBC
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Dr Ivonne Solis-Trapala
Deputy Lead, NIHR Research Design Service, West Midlands (Keele Hub)
Senior Lecturer in Medical Statistics
Research Institute for Primary Care and Health Sciences
and Keele Clinical Trials Unit
Faculty of Medicine and Health Sciences
Keele University
Staffordshire, ST5 5BG
Room DJW1.51, e-mail: [log in to unmask]
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