Medical Diagnostic Tests: A Review of Test Anatomy, Phases, and Statistical Treatment of Data

Abstract

Diagnostic tests are approaches used in clinical practice to identify with high accuracy the disease of a particular patient and thus to provide early and proper treatment. Reporting high-quality results of diagnostic tests, for both basic and advanced methods, is solely the responsibility of the authors. Despite the existence of recommendation and standards regarding the content or format of statistical aspects, the quality of what and how the statistic is reported when a diagnostic test is assessed varied from excellent to very poor. This article briefly reviews the steps in the evaluation of a diagnostic test from the anatomy, to the role in clinical practice, and to the statistical methods used to show their performances. The statistical approaches are linked with the phase, clinical question, and objective and are accompanied by examples. More details are provided for phase I and II studies while the statistical treatment of phase III and IV is just briefly presented. Several free online resources useful in the calculation of some statistics are also given.

Figure 1

Summary receiver operating characteristic (ROC) curve for BMI as an anthropometric marker to distinguish benign from malign breast tumors. The red line shows an equal proportion of correctly classified breast cancer sample and incorrectly classifies samples without breast cancer (random classification). The J max (max (Se + Sp − 1)) corresponds to a Se = 0.67 and a Sp = 0.88 for a cutoff > 29.5 kg/m² (BMI) for the breast cancer sample.