Learning about treatment effects in a new target population under transportability assumptions for relative effect measures.

ABSTRACT: Investigators often believe that relative effect measures conditional on covariates, such as risk ratios and mean ratios, are "transportable" across populations. Here, we examine the identification of causal effects in a target population using an assumption that conditional relative effect measures are transportable from a trial to the target population. We show that transportability for relative effect measures is largely incompatible with transportability for difference effect measures, unless the treatment has no effect on average or one is willing to make even stronger transportability assumptions that imply the transportability of both relative and difference effect measures. We then describe how marginal (population-averaged) causal estimands in a target population can be identified

SUBMITTER: Dahabreh IJ 

PROVIDER: S-EPMC11663256 | biostudies-literature | 2024 Sep

REPOSITORIES: biostudies-literature