Invited Commentary: Conducting and Emulating Trials to Study Effects of Social Interventions

All else equal, if we have one causal effect we wish to estimate, we would conduct the randomized trial with a protocol that maps onto that causal question, or we would attempt to emulate that target trial with observational data. However, studying the social determinants of health often means there is not just one but several causal contrasts of simultaneous interest and importance, and each of these related but distinct causal questions may have varying degrees of feasibility in conducting trials. With this in mind, we discuss challenges and opportunities when conducting and emulating such trials. We describe designing trials with the simultaneous goals of estimating the intention-to-treat effect, the per-protocol effect, effects of alternative protocols or joint interventions, effects within subgroups, and effects under interference, and we describe ways to make the most of all feasible randomized trials and emulated trials using observational data. Our comments are grounded in the trial results from Courtin et al. (Am J Epidemiol. XXXX;XXX(XX):XXXX–XXXX).