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Table 1 Characteristics of three generic forms of surgical trials

From: The challenges faced in the design, conduct and analysis of surgical randomised controlled trials

Study characteristic

Exploratory trial

Explanatory trial

Pragmatic trial

Aim of evaluation

To explore the impact of the intervention

To assess whether the intervention is efficacious

To assess whether the intervention is effective

Patient population

Initially those presumed to be most likely to benefit, though later modification is allowed

Narrow inclusion criteria of patients expected to be most suited to treatment

Broad inclusion criteria reflecting variations in clinical practice between centres

Surgical setting

Surgeon(s) with substantial generic surgical expertise

Surgeon(s) with expertise in the intervention under evaluation

Surgeons from multiple centres representing different levels of expertise

Intervention definition

Freedom to develop and refine

Tight definition and strictly controlled

Broader definition incorporating variations which reflect clinical practice

Outcomes of main focus

Surgical process and short-term clinical outcomes

Short-term (sometimes surrogate) clinical outcomes

Longer-term clinical and patient-reported outcomes (such as quality of life measures)