At the moment, with the exponential increase of the investigations and publications related to medical sciences and their compatible disciplines, it is practically impossible to use traditional methods of integration of the results obtained in the studies on a specific subject. In these methods, calls qualitative revisions, in which the integration method does not incorporate the use of formal statistical procedures, generally the revisory one takes each study by its value pretends and tries to find a theory that reconciles the contradictory results. On the other hand, Gene Glass, in 1976, proposed an integration method that uses the statistical tools in its analyses and to that it called metanálisis. The metanálisis (it puts, in Greek, after, and analisis, description, interpretation), consists of the statistical analysis of a great collection of extracted results of individual works in order to integrate the obtained results.