4/9/25 Seminar: "Improving the Efficiency of Estimators for Survival in Resampling Designs"

Continuing our CTML Seminar Series is CTML GSR, Kirsten Landsiedel. Her talk, "Improving the Efficiency of Estimators for Survival in Resampling Designs" will take place on April 9th at 12:00PM at Berkeley Way West, 5th Floor, Room 5401. You won't want to miss it! 

Survival is a key metric for evaluating current standards of care for individuals living with HIV. In resource-limited settings, high rates of loss to follow-up (LTFU) often result in underestimation of mortality when only observed deaths are considered. Resampling, which tracks a subset of LTFU patients to ascertain their outcomes, mitigates bias and improves survival estimates. However, common estimators for survival in resampling designs—such as weighted Kaplan-Meier (KM)—fail to leverage covariate information collected during repeated clinic visits, even though this information is highly predictive of survival.
We propose a novel Targeted Maximum Likelihood Estimator (TMLE) for survival in resampling designs, which addresses these limitations by leveraging baseline and longitudinal covariates to achieve greater efficiency. We present: (1) a fully efficient TMLE for data from resampling studies with fixed follow-up time for all participants and (2) an inverse probability of censoring weighted (IPCW) TMLE that accounts for varied follow-up times by stratifying on patients with sufficient follow-up to evaluate survival. This IPCW-TMLE can be made highly efficient through nonparametric or targeted estimation of the follow-up censoring mechanism.