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.