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Section IV : Study Population & Setting

For Pragmatic Trials

Key Points

  • A critical characteristic of pragmatic trials is the inclusion of diverse populations from multiple, heterogeneous settings.
  • PRECIS-2 identifies two domains related to Study populations (i.e., eligibility and recruitment) and two domains related to Settings (i.e., setting and organization)
  • Pragmatic studies:
    • Have fewer exclusion criteria than explanatory ones and include a population that is characterized to be similar to  the individuals with the given condition;
    • Use recruitment approaches that build on existing care procedures;
    • Are conducted in multiple settings similar to the ones in usual care;
    • Deliver the intervention via providers who interact with participants with the condition in usual care, require little or no additional resources, and line up the delivery of the intervention with exiting care delivery processes as closely as possible.

 

Learning Objective:

Describe and apply the PRECIS-2 domains of eligibility, recruitment, settings and organization, as well as the unique characteristics of study population and setting as applied to pragmatic trials. 

Study Populations

The Study populations domains are concerned with the questions of “Who is selected to participate in the study?” (Eligibility) and “How participants are recruited into the study?” (Recruitment). In the context of PRECIS-2, “participants" include patients or other individual recipients of an intervention, and/or providers of the intervention. This may include individual participants and/or one or more levels of clusters. For example, in a trial of a continuing education intervention, participants may be health professionals and trained instructors and the trial may be randomized into clusters at the level of the instructor.

Hover to Reveal description

PRECIS-2 Domain:

Eligibility

Who is selected to participate? - to what extent are the participants in the trial similar to those who would receive this intervention if it was part of usual care?

PRECIS-2 Domain:

Recruitment

How are participants recruited? - how much extra effort is made to recruit participants over and above what that would be used in the usual care setting to engage with patients?

The Study Populations Domains

Eligibility

To assess the Eligibility domain, we want to evaluate to what extent are the participants in the trial similar to those who would receive this intervention if it was part of usual care.

Explanatory studies tend to have more exclusion criteria than pragmatic ones. Typical reasons for exclusion include:

(1) excluding participants not known/shown to be highly compliant to the interventions under study;

(2) excluding participants not known/shown to be at high risk for the primary trial outcome

(3) excluding participants not expected to be highly responsive to the experimental intervention.  The goal of these exclusions is typically to exclude participants who are less likely to respond to the intervention (Loudon, 2015).

Recruitment

The Recruitment domain refers to the amount of extra effort that is made to recruit participants over and above what that would be used in the usual care setting to engage with patients?

Settings

The Settings domains are concerned with the questions of “Where is the study being done?” (Setting) and “What expertise and resources are needed to deliver the intervention? (Organization).

Hover to Reveal Description

PRECIS-2 Domain:

Setting

Where is the trial being done? - how different is the setting of the trial and the usual care setting?

PRECIS-2 Domain:

Organization

What expertise and resources are needed? - how different are the resources, provider expertise and the organization of care delivery in the intervention arm of the trial and those available in usual care?

The Settings Domains

Settings

The Setting domain in PRECIS-2 assesses how different is the setting of the study from the usual care setting. Pragmatic trials encourage the selection of multiple, diverse settings in which the intervention would be delivered. More explanatory trials would be characterized by fewer or a single source for the participants (Loudon, 2015).

Organization

The Organization domain explores the difference between the resources, provider expertise and the organization of care delivery in the intervention arm of the study and those available in usual care. Increased resource needs, specialized provider expertise and deviance from usual care delivery processes pushes the study to the more explanatory end of the continuum.  For example providers delivering the intervention can be restricted to ones with

(1) some defined experience in working with the subjects like the ones to be enrolled in the study;

(2) specialty certification relevant to the given intervention;

(3) experience with the actual intervention (Loudon, 2015).

Diverse Settings - An Example

Krist and colleagues in their pragmatic study of the implementation of the My Own Health Report (MOHR) identified 18 sites to participate. 

Each collaborating research team identified one or two pairs of primary care practices within their network that were similar with respect to practice type (e.g., FQHC or PBRN, family practice or internal medicine), practice ownership, geographic region, EHR infrastructure, and patient population served. 

Practice pairs were purposefully selected to represent the diversity of primary care settings and populations to ensure greater generalizability of results.

Krist et al, Designing a valid randomized pragmatic primary care implementation trial: the my own health report (MOHR) project. Implement Sci. 2013; 8: 73.

Applying PRECIS-2 Domains

More Pragmatic . . . 

More Explanatory . . .

Eligibility

Identical to those in usual care.

Include a number of exclusions (e.g. those who don’t comply, respond to treatment, or are not at high risk for primary outcome, are children or elderly), or uses many selection tests not used in usual care.

Recruitment

Use usual appointments or clinic
Use targeted invitation letters, advertising in newspapers, radio plus incentives and other routes that would not be used in usual care.

Setting

Use identical Settings to Usual Care
Selection of a single center or specialized or academic centers.

Organization

Allows for the delivery of the intervention by any provider treating study participants in the usual care setting, requiring no additional resources than the ones utilized in usual care, and delivering the intervention using existing care delivery channels

Limits the delivery of the intervention to providers with specialized training/expertise, would require additional resources (e.g., increased staff time), and require deviation from /additional steps to the usual care process.

 

Other Resources

Study Population & Setting (CRISP) Pragmatic Trials Workshop September 15, 2014

Borsika Rabin, PhD, MPH, PharmD
Borsika Rabin, Reviews the PRECIS-2 domains from this section in population and setting. 

Study Population and Setting - CRISP Pragmatic Trials Workshop 

Elaine Belansky, PhD
Elaine Belansky discusses applications of study pupulation and setting.

Key Takeaways

Click To Reveal Flipcard Answer

A critical characteristic of pragmatic trials is the inclusion of . . .

diverse populations from multiple, heterogenous settings.

Which are the two  domains identified by PRECIS-2 to study populations? To settings?

Study Population: Eligibility and Recruitment (who is selected and why)

Setting: Settings and organization (where the trial is done and what expertise and resources are needed)

Name a few defining characteristics of pragmatic studies: 

  • Have fewer exclusion criteria than explanatory ones and include population that is characterized to be similar to individuals with the given condition;
  • Use recruitment approaches that build on exiting care procedures;
  • Are conducted in multiple settings similar to the ones in usual care;
  • Deliver the intervention via providers who interact with participants with the condition in usual care, require little or no additional resources, and line up the delivery of the intervention with exiting care delivery processes as closely as possible.

References

Click Each Reference to View the Abstract and Download Full Texts.
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