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Table 1 Key differences between trials with explanatory and pragmatic attitudes (from Zwarenstein et al. [48]).

From: Making trials matter: pragmatic and explanatory trials and the problem of applicability

 

Explanatory attitude

Pragmatic attitude

Question

Efficacy: can the intervention work?

Effectiveness: does the intervention work when used in normal practice?

Setting

Well resourced, 'ideal' setting

Normal practice

Participants

Highly selected; poorly adherent participants and those with conditions which might dilute the effect are often excluded

Little or no selection beyond the clinical indication of interest

Intervention

Strictly enforced and adherence is monitored closely

Applied flexibly as it would be in normal practice

Outcomes

Often short-term surrogates, or process measures

Directly relevant to participants, funders, communities and healthcare practitioners

Relevance to practice

Indirect: little effort is made to match the design of the trial to the decision making needs of those in the usual setting in which the intervention will be implemented

Direct: the trial is designed to meet the needs of those making decisions about treatment options in the setting in which the intervention will be implemented