How to conduct a high-quality systematic review on diagnostic research topics.

The methodological rigour of original studies on a diagnostic or prognostic research topic, and systematic reviews of these primary studies, varies; improving overall quality is warranted. This paper, the second of the series, outlines key concepts and essential steps required to conduct a high-quality systematic review on diagnostic topics. It is comprised of six aspects: clarifying the project objectives; generating an appropriate research question; searching the literature and selecting study criteria; assessing risk of bias of eligible studies, reporting and analyzing data, and interpreting data and making conclusions. This review emphasizes clarifying the role of the index test(s), including the "PIRO" components in a diagnostic research question, setting a hypothesis and threshold for an accurate test if needed, searching for existing systematic reviews, assessing the risk of bias for individual studies using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS)-2 tool, considering methodological heterogeneity before performing a meta-analysis, managing uninterpretable or inconclusive data, and assessing the overall quality of the aggregate evidence using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach. We believe clinicians and health researchers would benefit from this methodological training.