A new article published in the journal Trials provides a look at how the  Pragmatic–Explanatory Continuum Indicator Summary, or PRECIS, rating system can be applied to clinical trials designs in order to examine where a given study sits on the spectrum of explanatory versus pragmatic clinical trials.

The PRECIS-2 criteria are used to rate study designs as more or less “pragmatic” according to multiple domains that include participant eligibility, recruitment methods, setting, organization, analysis methods, primary outcomes, and more. In this context, “pragmatic” refers to trials that are designed to study a therapy or intervention in a “real world” setting similar or identical to the one in which the therapy will actually be used. Pragmatic trials stand in contrast to explanatory trials, which are typically designed to demonstrate the safety and efficacy of an intervention under highly controlled conditions and in carefully selected groups of participants, but which may also be difficult to generalize to larger or more varied populations.

Clinical trials are almost never wholly “explanatory” or wholly “pragmatic.” Instead, many studies exist somewhere on a spectrum between these two categories. However, understanding how these different attributes apply to trials can help researchers design studies that are optimally fit for purpose, whether that purpose is to describe a biological mechanism (as in an explanatory trial) or to show how effective an intervention is when used across a broad population of patients (as in a pragmatic trial).

In their article in Trials, authors Karin Johnson, Gila Neta, and colleagues  applied PRECIS-2 criteria to 5 pragmatic clinical trials (PCTs) being conducted through the NIH Collaboratory. Each trial was found to rate as “highly pragmatic” across the multiple PRECIS-2 domains, highlighting the tool’s potential usefulness in guiding decisions about study design, but also revealing a number of challenges in applying it and interpreting the results.

Study authors Johnson and Neta will be discussing their findings during the NIH Collaboratory’s Grand Rounds on Friday, January 22, 2016 (an archived version of the presentation will be available the following week).

Johnson KE, Neta G, Dember LM, Coronado GD, Suls J, Chambers DA, Rundell S, Smith DH, Liu B, Taplin S, Stoney CM, Farrell MM, Glasgow RE. Use of PRECIS ratings in the National Institutes of Health (NIH) Health Care Systems Research Collaboratory. Trials. 2016;17(1):32. doi: 10.1186/s13063-016-1158-y. PMID: 26772801. PMCID: PMC4715340.

You can read more about the NIH Collaboratory PCTs featured as part of this project at the following links:

ABATE (Active Bathing to Eliminate Infection)

LIRE (A pragmatic trial of Lumbar Image Reporting with Epidemiology)

PPACT (Collaborative Care for Chronic Pain in Primary Care)

STOP-CRC (Strategies & Opportunities to Stop Colon Cancer in Priority Populations)

TIME (Time to Reduce Mortality in End-Stage Renal Disease)

Additional Resources

An introductory slide set on PCTs (by study author Karin Johnson) is available from the Living Textbook:

Introduction to Pragmatic Clinical Trials

The University of Colorado Denver - Anschutz Medical Campus publishes an electronic textbook on pragmatic trials:

Pragmatic Trials: A workshop Handbook