Diagnostic Accuracy Studies: Sensitivity, Specificity, and Beyond

Diagnostic tests are central to medical care, and their evaluation remains methodologically challenging. This methodological article outlines the key measures used to quantify diagnostic accuracy, highlights common sources of bias and variability in diagnostic accuracy studies, and discusses how the clinical effectiveness of medical tests can be evaluated. Examples of diagnostic tests from various fields, including clinical, radiographic, biomarker, and emerging AI-based approaches, are discussed. We argue that diagnostic accuracy represents only the first step in test evaluation and must be complemented by assessments of feasibility, clinical impact, and patient-centered outcomes.