Table 1

Common similarities and differences between the design of classical and pragmatic RCTs

Feature of trial designClassical RCTPragmatic RCT
Control groupYesYes
Setting/ecology of care• Highly controlled
• Specialised centres (secondary or tertiary)
• Pragmatically controlled
• Usual care (> primary care)
Patient population• Highly selected
• Confirmed diagnosis
Narrow (“pure”) population
• Pragmatically selected
• Clinical diagnosis
Broad (“real-life”) population
Inclusion/exclusion criteriaManyFew
AdherenceVery good (stimulated and monitored)Low (real-world adherence)
Therapy• Blinded (single- or double-blind); or
• Open-label
Usually open-label to allow for effects of different technologies e.g. device or mode of administration
ComparatorPlacebo; and/or active treatmentActive treatment
OutcomeEfficacyReal-life effectiveness (comparative effectiveness)
SafetyUsually short-termShort-term and long-term