Identification of Survival Average Causal Effect

• Activity Number: 7
• Type: Invited
• Date/Time: Sunday, August 3, 2014 : 2:00 PM to 3:50 PM
• Sponsor: Biometrics Section
• Author(s): Eric Tchetgen*+
• Companies: Harvard School of Public Health

Abstract

In longitudinal studies, outcomes ascertained at follow-up are typically undefined for individuals who die prior to the follow-up visit. In such settings, outcomes are said to be truncated by death and inference about the effects of a point treatment or exposure, restricted to individuals alive at the follow-up visit, could be biased even if as in experimental studies, treatment assignment were randomized. To account for truncation by death, the survivor average causal effect (SACE), defines the effect of treatment on the outcome for the subset of individuals that would have survived regardless of exposure status. In this paper, the author nonparametrically identifies SACE by leveraging post-exposure longitudinal measurements that simultaneously mediate the effects of exposure on survival and on the outcome of interest. Careful consideration is given to an application concerning the evaluation of the effects of smoking on cognitive decline in an aging population subject to high mortality rate.