Easy! Ask yourself: does this paper address the research question I am trying to answer? If it does, include it, and if it doesn’t, exclude it. That being said, it’s sometimes tricky to figure out what’s useful and what’s not for a research question, which is why we recommend that you write a protocol to explicitly define your research question, inclusion criteria, and exclusion criteria before you start screening. If you want some help on how to write a protocol in NK, take a peek at these instructions.
Once you’ve got your protocol nailed down, you can go ahead and create a list of exclusion reasons that you expect to come across. For our example, a common exclusion reason for our AIS and thrombectomy nest would be “not related to mechanical thrombectomy.” You can then exclude all studies that do not report mechanical thrombectomy under this exclusion reason while you screen.