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Limitations of "pragmatic" trials

Complementary Medicine, Peninsula Medical School, Universities of Exeter and Plymouth, Exeter, UK

Correspondence to:
Correspondence to:
Professor E Ernst
Edzard.Ernst@pms.ac.uk

Keywords: clinical trials; pragmatic trials

The first 150 words of the full text of this article appear below.

Clinical trials testing the value of therapeutic interventions range between the two extremes of maximal internal or external validity. The former study, often called an efficacy trial, tests a treatment under optimal (that is, near laboratory) conditions, in which features such as the patient sample, the intervention, and the outcome measures are narrowly defined. Their research question is usually whether the treatment is efficacious when used under optimal conditions. Unfortunately this can mean that the findings are not generalisable—that is, the results of such studies cannot necessarily be transferred to the wider population.

At the other end of the spectrum, pragmatic (practical or effectivity) trials are aimed to approximate the reality of clinical practice. Pragmatic trials have been defined as "trials for which the hypothesis and study design are formulated based on information needed to make a decision".¹ The test treatment is often compared with clinically relevant interventions or . . . [Full text of this article]

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