Clinical practice guidelines have improved in quality over the past 10 years by adhering to a few basic principles, such as conducting thorough systematic reviews of relevant evidence and grading the recommendations and the quality of the underlying evidence. The large number of systems of measuring the quality of evidence and recommendations that have emerged are, however, confusing.¹

The mission of the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) working group is to help resolve the confusion among the different systems of rating evidence and recommendations. The group has wide representation from many organisations including the Agency for Healthcare Research and Quality in the US, the National Institute for Clinical Excellence for England and Wales, and the World Health Organization. Developing a new uniform rating system is challenging because all systems have limitations and because many organisations have invested a great deal of time and effort to develop their rating systems and are understandably reluctant to adopt a new system.

The GRADE working group first published the results of its work in 2004 in the BMJ.² A simpler, clinically oriented description will soon be published.³ GRADE has taken care to ensure its suggested system is simple to use and applicable to a wide variety of clinical recommendations that span the full spectrum of medical specialties and clinical care.

The GRADE system classifies recommendations in 1 of 2 levels—strong and weak—and quality of evidence into 1 of 4 levels—high, moderate, low, and very low. Evidence based on randomised controlled trials (RCTs) begins with a top rating on GRADE’s 4 level quality of evidence classification (table …