Evidence based medicine underscores the importance of evidence in health care decision making, but what strategies health care professionals should take when there is insufficient evidence to guide the practice is still unknown. This project aimed to answer this question by summarizing the current strategies, policies as well as investigate the viewpoints of guideline developers and test the influence of different strategies.
The aspects leading to insufficient evidence summarized from guideline manuals were also addressed in GRADE downgrading criteria for quality of evidence. Other aspects related to insufficient evidence considered the appropriate format of evidence, stating without randomized controlled trial, the evidence was insufficient. Nevertheless, different types of evidence were also factors to consider in the GRADE approach. These facts supported what GRADE working group had claimed that with GRADE approach “guideline panels may choose to rate the quality of evidence as low or very low”.
This study noticed there were variations in the description and definition of insufficient evidence, which might produce a misunderstanding in communication among different guideline groups.
In addtion, there is neither agreement on clear cut-off point or shresholdthreshold for insufficiency to determine which the minimum requirement was for being insufficient, nor agreement on whether the importance or weight of different criterion was the same.[16,18-21,23,25,26,28,33,34] Determining evidence is insufficient or not cannot be made without judgment. Thus, transparent and structured framework for assessing the quality of evidence could be helpful. The reasons or basis to be insufficient should always be made clear in the guideline development process.
There were variations also variation in strategies to cope with insufficient evidence. Guideline developers might restrict their recommendations: no recommendation at all, or recommendation against use, or recommendation for use in a restricted condition, or recommend further studies on this research question. They could also gathering more information, including studies or other factors to facilitate the decision making process. USPSTF was the only guideline group which provides a specific framework for insufficient evidence, and they suggested 4 domains to consider in guideline development process, which could provide more background information in facilitating decision making. However, similar but unstructured considerations of these factors in decision making process were also proposed by many guideline groups. [15,25] Variations among strategies could possibly lead to different inteprations, inconsistent or even opposite recommendations for the same evidence. Agreement on the definition or strategies is expected to be necessary and helpful in reducing inconsistency and misunderstanding.
Phase I and Phase II studies both studied definition of insufficient evidence. In...