Studies Using Randomized Trial Data to Compare Nonrandomized Exposures

Annals of Internal Medicine
7 April 2020 Vol: 172, Issue 7


Understanding Clinical Research |7 April 2020
Studies Using Randomized Trial Data to Compare Nonrandomized Exposures
Catharine B. Stack, PhD; Anne R. Meibohm, PhD; Joshua M. Liao, MD, MSc; Eliseo Guallar, MD, DrPH
Researchers frequently use data collected in randomized controlled trials to target questions that are beyond the scope of the original trial. For example, trial data may be used to explore the effects on outcomes of an exposure collected during the trial that was not the randomized intervention. Although such data originate from a randomized trial, the analyses do not have the protection from bias that randomization provides. Successful randomization tends to balance observed and unobserved characteristics between study groups. Comparisons of nonrandomized exposures, even when done using trial data, can be biased and require analytic approaches commonly used for observational…