Studies of Diagnostic Tests
Correct treatment depends on accurate diagnosis. Diagnostic tests may include simple procedures such as physical signs or physical examination, as well as blood tests and radiologic imaging. Few diagnostic tests, however, can be relied on to yield accurate diagnoses 100% of the time. Thus, it is important to study the performance of diagnostic tests. Bossuyt et al35 stated:
Exaggerated and biased results from poorly designed and reported diagnostic studies can trigger their premature dissemination and lead physicians into making incorrect treatment decisions. A rigorous evaluation process of diagnostic tests before introduction into clinical practice could not only reduce the number of unwanted clinical consequences related to misleading estimates of test accuracy, but also limit health care costs by preventing unnecessary testing.
Studies to determine the diagnostic accuracy of a test are a vital part in this evaluation process. JAMA recommends that authors use the Standards for Reporting of Diagnostic Accuracy (STARD) checklist in reporting such analyses (www.consort-statement.org/Initiatives/newstand.htm).
Studies of diagnostic tests generally yield estimates of likelihood ratios, sensitivity, specificity, positive predictive values, and negative predictive values. Authors should report confidence intervals associated with these statistics. It is also common for these studies to report receiver operating characteristic curves.