What is a pragmatic trial?

Pragmatic RCT’s are reliable evaluations of health care effectiveness carried out under real world conditions. Although there is a recent upsurge of interest in pragmatic trials, led, amongst others by the Practihc group, the best descriptions of these trials are 20 years old.  (Schwartz, D., Lelouch, J. Explanatory  and pragmatic attitudes in therapeutic trials. Journal of Chronic Disease 1967; 20: 637-648).

Classic explanatory randomised trials (efficacy trials) test the effects, under idealised and tightly controlled conditions, of precisely characterised and specified treatments, on narrowly defined groups of individual patients.  The effects  may be assessed by the impact on physiological or chemical parameters, and the purpose is mainly to advance biomedical knowledge. Pragmatic trials, by contrast  are concerned with assessing the effects of interventions as they are usually used, in typical settings, and on typical users. The units studied may be hospital wards, clinics, health districts or other groups, as well as individual patients, practitioners or community members. Effectiveness of the intervention is usually assessed by impact on simple outcomes of importance to users of the intervention such as death, major disability, user satisfaction, cost and quality of care, and quality of life. 

Pragmatic trials are more interesting to policymakers than efficacy trials. Pragmatic trials are attuned to the same criteria of effectiveness as those used by policymakers – namely user perceptions, important and  visible outcomes, usual health service planning entities, and typical service limitations. Pragmatic trials take into account the varied ways that interventions are implemented in the real world.

Need more detail?

Trial Protocol Tool resource iconExplanatory trials v pragmatic trials from the 3rd edition of Clinical Epidemiology

Dave Sackett has written a good explanation of the difference between explanatory trials and pragmatic trials. The text was prepared it for the forthcoming 3rd edition of Clinical Epidemiology; A Basic Science for Answering Questions about Health Care, to be published by Lippincott, Williams & Wilkins in 2005. 

This page was last updated 3rd April 2005.