The phrase ‘pragmatic trial’ was first raised and coined by Schwarz and Llellouch in 1967, who made a distinction between explanatory and pragmatic approaches when conducting clinical trials:
Explanatory and pragmatic attitudes in therapeutical trials
Schwartz D, Lellouch J. Explanatory and pragmatic attitudes in therapeutical trials. Journal of chronic diseases. 1967 Aug 31;20(8):637-48.
Pragmatic trials have become an area of recent growing interest, in particular within health systems research. In a pragmatic trial the design mimics as closely as possible routine practice. However, initial dichotomies between explanatory and pragmatic trial design have been more usefully re-conceptualised as a continuum:
A pragmatic-explanatory continuum indicator summary (PRECIS): a tool to help trial designers
Thorpe KE, Zwarenstein M, Oxman AD, Treweek S, Furberg CD, Altman DG, Tunis S, Bergel E, Harvey I, Magid DJ, Chalkidou K. A pragmatic–explanatory continuum indicator summary (PRECIS): a tool to help trial designers. Journal of clinical epidemiology. 2009 May 31;62(5):464-75.
One design that has proved of particular interest is the Stepped-Wedge Cluster Randomised Design. A systematic review done in 2010 by Medege and colleagues shows that the phased roll-out of a Stepped-Wedge design is used to evaluate interventions when a decision has already been made to implement the intervention:
Systematic review of stepped wedge cluster randomized trials shows that design is particularly used to evaluate interventions during routine implementation
Mdege ND, Man MS, Taylor CA, Torgerson DJ. Systematic review of stepped wedge cluster randomized trials shows that design is particularly used to evaluate interventions during routine implementation. Journal of clinical epidemiology. 2011 Sep 30;64(9):936-48.
However, correspondence and comment from Kotz and colleagues highlight some of the continuing controversies in this area:
Use of the stepped-wedge design cannot be recommended: A critical appraisal and comparison with the classic cluster randomized controlled trial design.
Kotz D, Spigt M, Arts IC, Crutzen R, Viechtbauer W. Use of the stepped wedge design cannot be recommended: a critical appraisal and comparison with the classic cluster randomized controlled trial design. Journal of clinical epidemiology. 2012 Dec 31;65(12):1249-52.
Pragmatic Trials in Practice
Many trials conducted by researchers at LSHTM incorporate principles from the pragmatic end of the trial spectrum, in particular to address and improve external validity. Specific examples include:
The XTEND Trial – Xpert for TB: Evaluating a New Diagnostic
Effectiveness of a structured educational intervention using psychological delivery methods in children and adolescents with poorly controlled type 1 diabetes: a cluster-randomized controlled trial of the CASCADE intervention
Christie D, Thompson R, Sawtell M, Allen E, Cairns J, Smith F, Jamieson E, Hargreaves K, Ingold A, Brooks L, Wiggins M. Effectiveness of a structured educational intervention using psychological delivery methods in children and adolescents with poorly controlled type 1 diabetes: a cluster-randomized controlled trial of the CASCADE intervention. BMJ Open Diabetes Research & Care. 2016 Jun 1;4(1):e000165.