Developing a framework for assessing the applicability of the target condition in diagnostic research

What is the problem? Doctors use tests to help to decide if a person has a certain condition. They want to know how accurate the test is before they use it. This means how well it can tell people who have the condition from people who do not have it. This information can be found in "diagnostic systematic reviews". Diagnostic systematic reviews start with a research question. They bring together findings from studies that have already been done to try to answer this question. It is important for researchers to check that the studies match the review question. This is called an "applicability assessment". For example, if the review looks at children, it is important to check whether the studies look at children too. There is a tool named "QUADAS-2" that can be used to check how well the studies match the review question. This can be hard to do, and there are not many examples available to help people. What did we do? We wanted to know more about how people judge applicability concerns using the QUADAS-2 tool. We also wanted to write guidance to support judgments about applicability. What did we find? We found examples of how people are doing applicability assessment. Many reviews have not done it right, and we explain why this is. We also made guidance to help people with applicability assessment.