Target Trial Emulation: A Call for More Widespread Use.

Abstract

Causal inference methods intended for use with observational data have been widely available for decades, but barriers exist to their widespread adoption. These likely include lack of familiarity with several methodologic techniques often used in combination in these investigations such as inverse probability of treatment weighting and g-estimation, and the intensity of computational effort to employ these techniques. Even with these methods, critical design flaws undermine the ability to make valid causal inference in some studies. Identification of the need to explicitly pair study design elements with these causal inference methods led to development of a methodologic approach recently termed target trial emulation. This approach requires that investigators define a hypothetical randomized trial, emulate that hypothetical protocol in assembling the cohort and defining study elements and then conduct an analysis that attempts to mirror random treatment assignment. In the article by Heindel et al. (Am J Epidemiol. 2024;XXX(XX):XXXX-XXXX), the authors successfully emulate a target trial of systemic heparin during arteriovenous fistula creation on short-term endpoints by utilizing two existing randomized trials with key confounders available. Target trial emulation provides a framework to promote valid inference and generate high-quality contributions to the literature and its use should be expanded.