Pragmatic clinical trials

doi:10.1016/j.ctim.2004.07.043

Complementary Therapies in Medicine

Volume 12, Issues 2–3, June–September 2004, Pages 136-140

https://doi.org/10.1016/j.ctim.2004.07.043 Get rights and content

Summary

Both pragmatic and explanatory randomised controlled trials have a useful role to play in the evaluation of health care interventions. In this descriptive article, the key steps in conducting a pragmatic trial are described. The strengths and limitations of pragmatic trials are also discussed. The main strength of pragmatic trials is that they can evaluate a therapy as it is used in normal practice. Comparisons are made between pragmatic and explanatory trials, on the understanding that trials may have aspects to them that make the trial more of a hybrid. A case is made for the appropriate use and relevance of pragmatic trials in the evaluation of alternative and complementary medicine.

Introduction

Clinical trials can be designed to be either pragmatic or explanatory.¹ Pragmatic trials are designed to find out about how effective a treatment actually is in routine, everyday practice. Explanatory trials are designed to find out whether a treatment has any efficacy (usually compared with placebo) under ideal, experimental conditions. Both have a place in our repertoire of research methods. In this paper I will describe the key steps in undertaking a pragmatic trial, and describe some differences from an explanatory trial. My focus will be on the parallel-arm design, although the principles can be applied to other types of study. I will explore some of the strengths and weaknesses of pragmatic trials. I will then make some comparisons between archetypal pragmatic and explanatory trials, while acknowledging that some trials have hybrid designs. Finally I will make a case for the relevance of pragmatic trials in the clinical evaluation of complementary therapies.

Section snippets

Appropriate research question

The study design should match the clearly defined research question: if you are interested in evaluating the benefits of a therapy in everyday practice, then you need to use a normal clinical setting and a pragmatic design. Pragmatic trials answer questions about the overall effectiveness of an intervention, and cannot study the contributions of its different components. You would use a pragmatic trial to test an overall ‘package’ of care, including the contribution of the therapeutic

Limitations

The pragmatic trial design cannot be used to determine precisely what components within the treatment process might have caused any benefits, since it is a package of care that is being evaluated. For example, acupuncture is not being tested against a sham or “placebo” intervention, so pragmatic trials will not help isolate the effect of the needling per se. Therefore, the extent that the therapeutic relationship contributes to any overall benefit remains unknown after a pragmatic trial. Using

Comparing pragmatic and explanatory designs

Some features of explanatory and pragmatic trials can be presented archetypically as polar opposites (see Table 1). However, many randomised controlled trials lie somewhere along the spectrum between these two designs. For example, if a pragmatic trial has a more tightly specified treatment protocol than allowing practitioners a free hand to treat normally, then the design is no longer fully pragmatic. Nevertheless Table 1 is intended to highlight the key differences that inform the two types

Conclusion

Both explanatory and pragmatic trials have an important place in the evaluation of health care interventions, but they answer different research questions. Pragmatic trials are useful in answering questions about how effective a therapy is when compared to some standard or accepted treatment. They also overcome some specific difficulties that can be encountered with explanatory trials of complementary therapies, for example when evaluating complex packages of care. Pragmatic trial results can

Acknowledgements

Acknowledgements are due to Adrian White, Sylvia Shroer and Elaine Weatherley-Jones who all made useful suggestions that helped in the editing of this article.

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View full text

Pragmatic clinical trials

Summary

Introduction

Section snippets

Appropriate research question

Limitations

Comparing pragmatic and explanatory designs

Conclusion

Acknowledgements

J Chronic Dis

Comp Ther Med

Comp Ther Med

Comp Ther Med

Consensus development methods, and their use in creating clinical guidelines

The efficacy of acupuncture in the treatment of major depression in women

Psychol Sci

Patient perspectives on outcomes after treatment with acupuncture

J Alt Comp Med