Estimation of the survival-incorporated median: a summary measure for outcomes truncated by death

Music City Center 

The problem of "truncation by death" commonly arises in clinical studies: subjects may die before their follow-up assessment, resulting in undefined clinical outcomes. In this work, rather than treating death as a mechanism through which clinical outcomes are missing, we advocate treating death as part of the outcome measure. We propose using the survival-incorporated median-the median of a composite outcome combining death and clinical outcomes-to summarize the clinical benefit of treatment. Combining Inverse Probability of Treatment Weighting and a quantile estimation procedure, we propose an estimation method for the survival-incorporated median, applicable to both point treatment settings and time-varying treatment settings. We prove the consistency and the asymptotic normality for the proposed estimator. We apply this method to estimate the cognitive effects of statins in participants from Long Life Family Study, an observational study involving over 4953 older adults with familial longevity. Through this application, we aim to not only contribute to the clinical understanding of the cognitive effects of statins, but also offer insights into analyzing clinical outcomes.

Causal inference

Truncation by death

Survival

Quantile estimation

Observational study 

Biometrics Section