SYSTEM Research note on: An attempt to quantify degrees of beliefs concerning the precision and internal validity of systematic review conclusions

CONTEXT: Systematic review evidence provides best justification for specific beliefs regarding clinical interventions. The degree of such belief depends on the precision and internal validity of the evidence. While precision is often achieved on basis of quantification and statistical analysis, the (internal) validity of the evidence is appraised through judgement of the risk for several known biases. Against the background of the subsequent results, a conclusion is formulated in answer to a specific systematic review question.

PROBLEM: Currently, systematic reviews do provide quantification of its results, e.g., by use of meta-analysis, from which conclusions are induced. However, no quantification is given concerning the degree of belief that such conclusions are coherent with the current evidence and the degree of belief that the current evidence corresponds with reality.

SUGGESTED SOLUTION: This article presents a simple method how such degrees of beliefs may be quantified. The quantification of degrees of beliefs may be beneficial in illustrating the precision and internal validity of systematic review results. Such illustration may assist the users of systematic review evidence in gaining an intuitive first impression of its merits. However, inter-systematic review comparison based on such quantification is limited and the quantified degrees of belief reflect to a large extent the subjectivity of systematic review authors.