Speaker
Description
A question that arises in the analysis of adverse events is how to account for patients who withdraw their consent or switch treatment. One approach is to consider consent withdrawal and treatment switch as competing events. Alternatively, patients who withdraw from the study or switch treatment could be censored, but this implies that one assumes censoring due to treatment switch or consent withdrawal not to be related to the treatment or any disease stage, i.e., to be random. In other words, this approach assumes that patients who do not withdraw consent and do not switch treatment are representative of those who do, which may be invalid. These two approaches to handling consent withdrawals and treatment switches in the analysis of adverse events were also discussed by the SAVVY project [1]. As an alternative, inverse probability of censoring weighting (IPCW) can be used to answer questions in a hypothetical world in which a treatment switch or consent withdrawal does not occur. For this, patients who do not withdraw their consent or switch treatments will be up-weighted to represent those who do. In this talk, we will discuss the construction of IPCW estimators in competing events analyses and the assumptions under which IPCW can be used to causally analyse the hypothetical scenario in which a competing event does not occur using data from a randomised study in elderly AML patients investigating the effects of valproate and retinoic acid [2]. Our approach distinguishes between ‘hard’ and ‘soft’ competing events in that hypothetical IPCW calculations are not applied to competing mortality.
References
[1] Stegherr R, Beyersmann J, Jehl V, Rufibach K, Leverkus F, Schmoor C, and Friede T. Survival
analysis for AdVerse events with VarYing follow-up times (SAVVY): Rationale and statistical concept
of a meta-analytic study. Biometrical Journal, 63:650–670, 2021.
[2] Lübbert M, Grishina O, Schmoor C, et al. Valproate and retinoic acid in combination with decitabine in elderly nonfit patients with acute myeloid leukemia: Results of a multicenter, randomized, 2 × 2, phase II trial. Journal of Clinical Oncology, 38:257–270, 2020.
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