Heterogeneity in pragmatic randomised trials: sources and management

Area of Science:

• Clinical Trials
• Health Services Research
• Evidence-Based Practice

Background:

• Pragmatic trials generate evidence for real-world patient and health system decisions.
• Patient characteristics are a key source of outcome heterogeneity in trials.
• Other clinical and methodological factors also contribute to outcome variability.

Purpose of the Study:

• To identify and discuss sources of clinical and methodological heterogeneity in pragmatic trials.
• To illustrate strategies for managing heterogeneity throughout the trial process using real-world examples.
• To emphasize welcoming, rather than limiting, heterogeneity to enhance trial applicability.

Main Methods:

• Welcoming heterogeneity in patients and centers.
• Allowing flexible or tailored interventions and usual care controls.
• Permitting co-interventions and avoiding enforced adherence.
• Prioritizing objective, routinely collected outcomes and minimizing standardization, blinding, and adjudication.
• Employing intention-to-treat analysis and incorporating unobtrusive process analyses.
• Integrating ethical consent procedures within the care pathway.

Main Results:

• Heterogeneity in interventions and outcomes should be embraced as it mirrors real-world practice.
• Minimizing standardization and maximizing objective outcomes enhances the applicability of trial findings.
• Process analyses provide valuable insights into trial results and understanding.
• Ethical considerations, such as consent, can be integrated pragmatically into clinical workflows.

Conclusions:

• Pragmatic trials should actively manage and leverage heterogeneity to produce generalizable evidence.
• Embracing real-world complexities in trial design leads to more relevant findings for decision-makers.
• The principles of pragmatism can be balanced with ethical requirements to optimize trial conduct and impact.