Evidence is the core of Evidence-Based Medcine; the Grades of Recommendations Assessment, Development and Evaluation (GRADE System) is a milestone in the history of evidence development. This paper outlines the GRADE System and GRADEpro 3.2 software, and briefly explores the right and wrong application which was published in the Chinese Journal of Evidence-Based Medicine. The GRADEpro 3.2 software is easy to operate, but for evaluating the reasons of upgrade and downgrade, and the importance of the parameters of outcomes, it needs to comprehensively and systematically understand the knowledge of relevant background, and to construct a solid foundation in clinical epidemiology and systematic review. In view of this paper based on the current GRADE System, there may be some discrepancy to the later content with the GRADE System constant improvement. Therefore, it is bly recommended that readers should keep constant learning and improving.
A systematic literature search and a comparative study were conducted to investigate the evolution of the levels of evidence and strength of recommendations in medical research. Fifty systems were included from 1979 to 2007, and 11 of these, which came from five states or international organizations, were selected and divided into three stages according to their characteristics, sphere of influence and application fields. Ideas about levels of evidence and strength of recommendations are becoming mature in medical research. The challenge for the future is how to introduce evidence-based principles and develop the corresponding levels of evidence and strength of recommendations in the fields of management, education, basic medical sciences, economics, sociology and legal research.