PRECIS

The Pragmatic-Explanatory Continuum Indicator Summary (PRECIS) Framework

The Pragmatic-Explanatory Continuum Indicator Summary (PRECIS) framework is a tool designed to assist researchers in assessing and designing clinical trials along a continuum from explanatory (highly controlled) to pragmatic (real-world applicable). Its primary purpose is to ensure that the design of a trial aligns with its intended objective—whether that is testing efficacy under ideal conditions or evaluating effectiveness in routine care. Originally introduced in 2009, the framework was later refined into PRECIS-2, which expanded its usability and clarity for practical trial design.

Purpose of PRECIS

Many clinical trials are planned without clearly distinguishing whether their design leans toward explanatory or pragmatic aims. This can result in a mismatch between how a trial is conducted and the context in which its findings are intended to be applied. PRECIS helps to resolve this issue by enabling researchers to evaluate how each component of their trial supports its purpose. By visualizing and scoring the degree of pragmatism or explanatory control across various domains, the PRECIS framework promotes consistency, enhances transparency, and ensures relevance for clinicians, policy-makers, and health system stakeholders.

PRECIS-2 Domains

PRECIS-2 identifies nine domains that collectively describe the pragmatic or explanatory nature of a trial. Each domain is scored on a spectrum, from more explanatory (idealized conditions) to more pragmatic (real-world conditions):

Eligibility Criteria

Assesses how inclusive the study population is, and how closely it reflects the typical patients seen in routine clinical practice.

Recruitment

Evaluates whether recruitment is carried out through specialized processes or integrated within general clinical workflows.

Setting

Looks at whether the trial setting mirrors usual care environments or involves tightly controlled clinical contexts.

Organization

Considers the degree to which additional infrastructure, training, or resources are required to implement the intervention compared to routine practice.

Flexibility in Delivery

Determines whether clinicians must follow strict protocols for delivering the intervention or can exercise clinical discretion.

Flexibility in Adherence

Assesses how strictly participant adherence is enforced and whether it reflects natural behavior outside a trial context.

Follow-Up Intensity

Evaluates whether follow-up procedures are typical of standard care or involve additional contact and monitoring beyond routine practice.

Primary Outcome

Considers whether the outcomes are mechanistic and surrogate (e.g., biomarkers, lab results) or patient-centered (e.g., symptom relief, quality of life).

Analysis

Determines whether analysis is conducted using an intention-to-treat approach (pragmatic) or per-protocol/subgroup methods (explanatory).

Benefits of Using PRECIS-2

PRECIS-2 provides multiple benefits in trial design and interpretation. It improves alignment between study objectives and methodology, helping ensure that the trial answers the question it was intended to address. It enhances external validity by encouraging the inclusion of more representative populations and typical care settings. The tool also supports communication with stakeholders—such as clinicians, policymakers, and funders—by providing a clear visual summary of a trial’s design. In comparative effectiveness research, PRECIS-2 is particularly valuable for evaluating how interventions perform in everyday clinical settings.

Application in Research

PRECIS-2 is commonly used during the design phase of randomized controlled trials (RCTs), especially when researchers aim to evaluate effectiveness rather than efficacy. A common feature of its application is the use of the “PRECIS wheel”—a radar chart that visually maps the trial across all nine domains. This helps teams identify areas of inconsistency or misalignment and make necessary adjustments before the trial begins.

Challenges in Using PRECIS-2

Despite its utility, PRECIS-2 has some limitations. Scoring can be subjective, as it relies on the judgment of researchers or evaluators, potentially leading to inconsistencies. Additionally, not all domains need to be fully pragmatic or explanatory—many trials require a balance depending on the research question. Another challenge is that journal reporting standards do not always require PRECIS-2 assessments, limiting its widespread use and transparency in published trials.

Conclusion

PRECIS-2 is a valuable and increasingly adopted tool for improving the design, clarity, and relevance of clinical trials. By systematically evaluating trial elements along a pragmatic-explanatory spectrum, it helps researchers ensure that their studies are both scientifically rigorous and contextually appropriate. In doing so, PRECIS-2 contributes to more effective translation of research findings into practice, ultimately enhancing healthcare decision-making and patient outcomes.

You can read more about the PRECIS-2 Tool here: PRECIS-2 Home Page

Bibliography

Loudon K, Treweek S, Sullivan F, Donnan P, Thorpe KE, Zwarenstein M. The PRECIS-2 tool: designing trials that are fit for purpose. BMJ. 2015;350:h2147.
Thorpe KE, Zwarenstein M, Oxman AD, et al. A pragmatic–explanatory continuum indicator summary (PRECIS): a tool to help trial designers. CMAJ. 2009;180(10):E47–E57.
Loudon K, Zwarenstein M, Sullivan FM, Donnan PT, Treweek S. Making clinical trials more relevant: improving and validating the PRECIS tool for matching trial design decisions to trial purpose. Trials. 2013;14:115.
Nicholls SG, Carroll K, Zwarenstein M, et al. Stakeholder views on the PRECIS-2 tool and its use for planning pragmatic trials: a qualitative study. BMC Medical Research Methodology. 2019;19:210.
Dal-Ré R, Janiaud P, Ioannidis JPA. Real-world evidence: how pragmatic are randomized controlled trials labeled as pragmatic? BMC Medicine. 2018;16:49.

Adapted for educational use. Please cite relevant trial methodology sources when using this material in research or teaching.