Measures of diagnostic accuracy: basic definitions

TLDR

Diagnostic accuracy measures, such as sensitivity, specificity, predictive values, likelihood ratios, AUC, Youden's index, and diagnostic odds ratio, quantify a test’s ability to distinguish disease from health, but their values vary with disease prevalence, spectrum, definition, and study design, making methodological rigor essential for reliable performance assessment. The review aims to define and characterize diagnostic accuracy measures and to encourage the adoption of the STARD checklist in reporting studies. The authors provide concise definitions and characteristics of diagnostic accuracy metrics and recommend that journals mandate the STARD checklist for authors reporting such studies. The STARD initiative markedly improves reporting quality of diagnostic accuracy studies, potentially enhancing evidence for patient care.

Abstract

Diagnostic accuracy relates to the ability of a test to discriminate between the target condition and health. This discriminative potential can be quantified by the measures of diagnostic accuracy such as sensitivity and specificity, predictive values, likelihood ratios, the area under the ROC curve, Youden's index and diagnostic odds ratio. Different measures of diagnostic accuracy relate to the different aspects of diagnostic procedure: while some measures are used to assess the discriminative property of the test, others are used to assess its predictive ability. Measures of diagnostic accuracy are not fixed indicators of a test performance, some are very sensitive to the disease prevalence, while others to the spectrum and definition of the disease. Furthermore, measures of diagnostic accuracy are extremely sensitive to the design of the study. Studies not meeting strict methodological standards usually over- or under-estimate the indicators of test performance as well as they limit the applicability of the results of the study. STARD initiative was a very important step toward the improvement the quality of reporting of studies of diagnostic accuracy. STARD statement should be included into the Instructions to authors by scientific journals and authors should be encouraged to use the checklist whenever reporting their studies on diagnostic accuracy. Such efforts could make a substantial difference in the quality of reporting of studies of diagnostic accuracy and serve to provide the best possible evidence to the best for the patient care. This brief review outlines some basic definitions and characteristics of the measures of diagnostic accuracy.