How to conduct a high-quality original study on a diagnostic research topic

As health research methodologists and journal reviewers, we noticed that the methodological rigor of many publications on diagnostic or prognostic topics in the medical literature could be improved. We present a concise and clear series of reviews to help clinicians and health researchers to master the basic key components of how to conduct a high-quality original study or systematic review on a diagnostic or prognostic research topic from a methodological perspective. This is the first review of the series, which focuses on how to conduct a high-quality diagnostic study. We are introducing four aspects: clarifying the objectives; generating an appropriate research question; planning the study design; and reporting and analyzing data. This review highlights that diagnostic test accuracy outcomes are surrogates for patient outcomes, a diagnostic test has three roles, the "PIRO" components should be included in a diagnostic research question, a new study should be registered, multiple index tests can be compared in one study, and prevalence affects test accuracy outcomes. This review also emphasizes reporting any thresholds, calculating sample size, and performing a two-by-three table to calculate diagnostic outcomes.