Trends in the Explanatory or Pragmatic Nature of Cardiovascular Clinical Trials Over 2 Decades.

IMPORTANCE

Pragmatic trials test interventions using designs that produce results that may be more applicable to the population in which the intervention will be eventually applied.

OBJECTIVE

To investigate how pragmatic or explanatory cardiovascular (CV) randomized clinical trials (RCT) are, and if this has changed over time.

DATA SOURCE

Six major medical and CV journals, including New England Journal of Medicine, Lancet, JAMA, Circulation, European Heart Journal, and Journal of the American College of Cardiology.

STUDY SELECTION

All CV-related RCTs published during 2000, 2005, 2010, and 2015 were identified and included.

DATA EXTRACTION AND SYNTHESIS

Included RCTs were assessed by 2 independent adjudicators with expertise in RCT and CV medicine.

MAIN OUTCOMES AND MEASURES

The outcome measure was the level of pragmatism evaluated using the Pragmatic Explanatory Continuum Index Summary (PRECIS)-2 tool, which uses a 5-point ordinal scale (ranging from very pragmatic to very explanatory) across 9 domains of trial design, including eligibility, recruitment, setting, organization, intervention delivery, intervention adherence, follow-up, primary outcome, and analysis.

RESULTS

Of 616 RCTs, the mean (SD) PRECIS-2 score was 3.26 (0.70). The level of pragmatism increased over time from a mean (SD) score of 3.07 (0.74) in 2000 to 3.46 (0.67) in 2015 (P < .001 for trend; Cohen d relative effect size, 0.56). The increase occurred mainly in the domains of eligibility, setting, intervention delivery, and primary end point. PRECIS-2 score was higher for neutral trials than those with positive results (P < .001) and in phase III/IV trials compared with phase I/II trials (P < .001) but similar between different sources of funding (public, industry, or both; P = .38). More pragmatic trials had more sites, larger sample sizes, longer follow-ups, and mortality as the primary end point.

CONCLUSIONS AND RELEVANCE

The level of pragmatism increased moderately over 2 decades of CV trials. Understanding the domains of current and future clinical trials will aid in the design and delivery of CV trials with broader application.