Along with Dr. Holger Schünemann, Guyatt is the co-chair of the Grading of Recommendations Assessment, Development and Evaluation (GRADE) working group that began in the year 2000 as an informal collaboration of people with an interest in addressing the shortcomings of grading systems in clinical practice guidelines and systematic reviews. Guyatt played a key role in the development and refinement of the GRADE approach, a sensible and transparent structure for grading quality (or certainty) of evidence and strength of recommendations. The GRADE approach is now considered the standard in systematic review and guideline development with over 100 health care organizations worldwide having adopted the approach, including the World Health Organization, Centers for Disease Control, American College of Physicians and the Cochrane Collaboration.