The "pragmatic trial": An essentially contested concept?

For over 50 years, clinical research methodology has wrestled with the problem of the lack of correspondence between tests of treatments and applications of treatments. The former comprise of trials featuring scrupulous control of patient eligibility, treatment compliance, clinician expertise, follow-up intensity, and so on. In applying a validated treatment, the practitioner has to confront considerable real-world variation in potential patients and in implementation regimes. The remedy, going by the name of "pragmatic trials," is to conduct clinical trials in conditions corresponding more closely to everyday practice. This solution has proved easier to utter than to execute, and the paper reviews the extensive literature on pragmatic trials, seeking to assess whether it has terminated in clarity or contestation.