Estimation methods for treatment policy strategies in clinical trials with missing data: introducing retrieved dropout reference-base centred multiple imputation

Schedule: The talk will be approx. 1 hour, with discussion/Q&A 30 minutes

Location: Hybrid – Online via Teams / or in person at Nuffield Orthopaedic Centre ND08

(please note: the speaker will be online)

Speaker: Dr Suzie Cro (Imperial), Associate Professor in Medical Statistics and Clinical Trials, Head of Trial Methodology and co-Head of the Statistics section at Imperial Clinical Trials Unit

Abstract: A treatment policy strategy if often used to handle intercurrent events such as treatment withdrawal in clinical trials. Such an approach seeks to estimate the effect of a treatment, regardless of whether patients withdraw from the treatment schedule early. This requires the collection of outcome data following treatment withdrawal, however data is often missing after treatment withdrawal complicating the analysis.

In this setting, retrieved dropout multiple imputation has been proposed as a useful method for estimation. This approach imputes off-treatment data based only on observed off-treatment data. But this may be impractical with limited observed data post-treatment withdrawal. Alternatively, reference-based multiple imputation can be used which assumes treatment withdrawals behave like those observed in a specified reference group. But this makes strong assumptions and disregards observed off-treatment outcomes.

This presentation will review these two different methods of imputation followed by an introduction to a novel approach, referred to as retrieved dropout reference-base centred multiple imputation, that draws its influences from the two aforementioned methods. The expected bias and root mean square error (RMSE) for this new method will be analytically explored, followed by application to an anti-depression trial.

No registration required – if joining online please join the session here via Teams: https://teams.microsoft.com/meet/39849641209505?p=y2MDEjtwbfCI0V2A4j

Please note the talk will be recorded. The recording will end before the discussion/ Q&A.

If you should have any queries, please contact the session organisers: Chris Mwema christopher.mwema@ndorms.ox.ac.uk  & Dr Daphne Kounali daphne.kounali@ndorms.ox.ac.uk