Target trial emulation (TTE) is an approach to help facilitate causal inferences from an observational study. In the TTE paradigm, we try to emulate a randomized trial with data from an observational study. In doing so, we have to consider things like inclusion/exclusion criteria, treatment strategies, outcome measures, and the statistical analysis plan.
TTE can be a useful approach for estimating causal effects when it’s impractical to conduct an RCT.
When emulating a target trial, we want to consider the following 7 elements:
- Eligibility criteria: Who or what should be included in the study?
- Exposure definition: When eligible, what precise exposure will units under study receive?
- Assignment procedures: How will eligible units be assigned to an exposure?
- Follow-up period: When does follow-up start and end?
- Outcome definition: What precise outcomes will be measured?
- Causal contrast of interest: Which causal estimand will be estimated?
- Analysis plan: What data manipulation and statistical procedures will be applied to the data to estimate the causal contrast of interest?