You're on a clinical guideline panel and it's time to rate the evidence.
No worries. Your panel should have one or more methodologists to do the heavy lifting here. But you should have some understanding of the process, not only to know what's going on but to actively contribute.
Let's start with an overview of the process for rating a body of evidence.
Start with your outcomes. You should have specified all the outcomes of interest when you developed your clinical questions. The quality of the body of evidence will be rated separately for each of the outcomes you have selected.
Rating the body of evidence is different than rating the quality of the individual studies (though that is one of the components). There are several other criteria but most rating systems agree on at least these factors:
- An aggregate of all the assessments of the quality of the individual studies. The focus is on validity, or the minimization of bias in measurement within the studies
- The reproducibility of the the results from the individual studies. This focus is on consistency of effect and requires multiple tests or studies
- The power or precision of the measurements around the estimated effect and the strength of the effect
There are a number of systems to rate the evidence available to guideline developers. But one system has become commonly used or adapted for use by most guideline developers. It is known as the GRADE approach.
In a series of short blogs, TheEvidenceDoc will briefly describe some of the features and steps of the GRADE approach, particularly those that are often misunderstood by guideline panelists.
TheEvidenceDoc November 7, 2017