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Clinics (Sao Paulo). 2011;66(1):159-61.

Limits to clinical trials in surgical areas.

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  • 1Faculdade de Medicina, Universidade de Sao Paulo, São Paulo, São Paulo, Brasil.


Randomized clinical trials are considered to be the gold standard of evidence-based medicine nowadays. However, it is important that we point out some limitations of randomized clinical trials relating to surgical interventions. There are limitations that affect the external and internal validity of many surgical study designs. Some limitations can be bypassed, but can make it more difficult for the study to be carried out. Other limitations cannot be bypassed. When it is intended to extrapolate the result of a randomized clinical trial, the premise is that the performed or to be performed intervention will be similar wherever applied and/or for every doctor using it. However, no matter how standardized the technique may be, the results are not similar for all surgeons, which implies a significant limitation to surgical randomized clinical trials concerning external validity. When considering the various limitations presented for performing surgical trials capable of generating scientific evidence within the patterns currently proposed in the evidence level classifications of medical publications, it is necessary to rethink whether those scientific evidence levels are similarly applicable to surgical works and to nonsurgical trials. We currently live in a time of supposed ''inferiority'' of surgical scientific works under the optics of the current quality criteria for a ''suitable'' clinical trial.

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