GRADE notes: How to use GRADE when there is “no” evidence? A case study of the expert evidence approach

OBJECTIVES: One essential requirement of trustworthy guidelines is that they should be based on systematic reviews of the best available evidence. The GRADE Working Group has provided guidance for evaluating the certainty of evidence based on several domains. However, for many clinical questions, published evidence may be limited, too indirect or simply not exist. In this brief report (GRADE notes), we describe our method of developing evidence-based recommendations when publisheddirect evidence was lacking. STUDY DESIGN AND SETTING: When direct published literature was absent, an expert evidence survey was administered to panel members about their unpublished observations and case series. Focus was on collecting data about cases and outcome, not panel opinions. RESULTS: Out of 26 questions prioritized by the panel for pediatric venous thromboembolism, 12 had no, very limited, or very low certainty of evidence to inform them. The panel survey was administered for these questions. CONCLUSIONS: Areas of sparse evidence often reflect key questions that are critical to address in clinical practice guidelines due to the uncertainty among health care providers. The expert evidence approach used in this study is one method for panels totransparently deal with the lack of published evidence to directly inform recommendations.