Thoma A, Farrokhyar F, Bhandari M, Tandan V, Evidence-Based Surgery Working Group. Users’ guide to the surgical literature. How to assess a randomized controlled trial in surgery. Can J Surg 2004;47(3):200-8.


Clinicians are presented with problems that require evidence. Randomized controlled trials (RCTs) are considered the optimal study design for evaluating the effect of a new medical or surgical intervention. Surgical RCTs are carried out less often than RCTs of medical interventions, partly because using RCTs to evaluate surgical or interventional procedures is difficult and demands special consideration of issues such as blinding and the effects of surgeon factor, learning curve and differences in pre or postprocedural care. Despite these obstacles, RCTs are becoming more common as surgeons in many specialties become acquainted with the proper methodology for health research.

The mere description of a study as “randomized” does not allow clinicians to infer validity—to base inferences on the accuracy of the results
drawn from the sample of patients studied (internal validity) or the generalizability of these results to other settings (external validity). The purpose of this article is to review, within a framework of a critical appraisal of surgical RCTs, strategies to interpret the results and the issues to consider when applying these results to a clinical practice setting. A clinical scenario will be used to illustrate how surgeons might retrieve and evaluate evidence.

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