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Comment & Response
February 19, 2020

Pragmatic vs Explanatory Trials

Author Affiliations
  • 1Harborview Medical Center, Seattle, Washington
  • 2Department of Emergency Medicine, University of Washington, Seattle
  • 3Department of Internal Medicine, University of Washington, Seattle
JAMA Cardiol. Published online February 19, 2020. doi:10.1001/jamacardio.2019.6111

To the Editor We read with interest the study by Sepehrvand et al,1 which described secular trends in the conduct of pragmatic or explanatory cardiovascular randomized clinical trials over 2 decades. We believe extension of this thoughtful analysis can provide additional insights into pragmatic vs explanatory trials.

Pragmatic compared with explanatory trials are intended to study the effectiveness of interventions in routine clinical practice to facilitate enrollment and increase generalizability. They achieve this by incorporating broader eligibility criteria, more flexible interventions, simpler assessment of patient or physician compliance/adherence, and a more inclusive analysis of outcomes. Although each of these characteristics has some appeal, an unintended consequence may be that their cumulative effect lowers the likelihood of identifying an efficacious intervention. The latter would ultimately decrease the rate of evidence-based improvements in care.

We encourage the authors to examine whether there is an association between the proportion of trials that detect a significant difference in the primary outcome and the degree of pragmatism as measured by the Pragmatic Explanatory Continuum Index Summary (PRECIS)–2 score. We further encourage the authors to describe whether the proportion of positive trials has changed over time. While clinical research resources are limited and interventions should be evaluated in the real world, we have incomplete information about whether use of pragmatic trials is indeed an improvement in evidence-based medicine. Further analysis of the potential effect of use of pragmatic study designs on identification of efficacious interventions would provide important insights as to whether the current heavy emphasis on pragmatic designs is desirable.

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Article Information

Corresponding Author: Anoushka Fernandes, Harborview Medical Center, 325 Ninth Ave, PO Box 359727, Seattle, WA 98104 (anousf@uw.edu).

Published Online: February 19, 2020. doi:10.1001/jamacardio.2019.6111

Conflict of Interest Disclosures: Dr Bartlett has received grants from the ZOLL Foundation. Dr Nichol has received grants from the National Heart, Lung, and Blood Institute, Kettering Foundation, ZOLL Medical, and GE Healthcare; has received consulting fees from GE Healthcare, Kestra Medical Technologies, and Qool Therapeutics; receives salary support via an endowed research chair at the University of Washington from the Medic One Foundation; is a principal investigator for a multicenter trial funded by ZOLL Circulation; and has patents pending for nonimaging ultrasonography to measure blood flow during attempted resuscitation and a combination drug-device to treat reperfusion injury. No other disclosures were reported.

Sepehrvand  N, Alemayehu  W, Das  D,  et al.  Trends in the explanatory or pragmatic nature of cardiovascular clinical trials over 2 decades.  JAMA Cardiol. 2019;4(11):1122-1128. doi:10.1001/jamacardio.2019.3604PubMedGoogle ScholarCrossref