A clinical study examines the usefulness of 5 different biomarkers to detect Barrett esophagus (BE), the only known precursor lesion of esophageal adenocarcinoma. Researchers evaluate the performance of each biomarker and report the sensitivity, specificity, and area under the curve (AUC) estimates. Which of the biomarkers is most accurate?

Question

A clinical study examines the usefulness of 5 different biomarkers to detect Barrett esophagus (BE), the only known precursor lesion of esophageal adenocarcinoma.  Researchers evaluate the performance of each biomarker and report the sensitivity, specificity, and area under the curve (AUC) estimates.  Which of the biomarkers is most accurate?

Quizplus · Accepted Answer

11ec160b_371c_101c_9249_5d4d2a474165_MD0001_00 The accuracy of screening or diagnostic tests (defined as the number of true positives plus true negatives divided by the number of all observations) is generally quantified by the area under the ROC curve (AUC). ROC (receiver operating characteristic) curves are created by plotting sensitivity (true-positive rate) against 1 − specificity (false-positive rate) for various cutoff thresholds (ie, the value that determines if a given test result is positive or negative). A highly accurate test is highly sensitive (high true-positive rate) and highly specific (low false-positive rate). The more accurate the test is (ie, the higher sensitivity and specificity), the closer the AUC value is to 1.0. Therefore, tests with higher AUCs are more accurate than tests with lower AUCs. In this study, the ROCs for the tests (ie, biomarkers) are not provided; however, it is possible to draw conclusions about the accuracy of each biomarker based on the values given for their AUCs. Biomarker 3 has the largest AUC (0.879) compared to biomarker 1 (0.603), biomarker 2 (0.758), biomarker 4 (0.763), and biomarker 5 (0.756). Therefore, biomarker 3 is the most accurate test of the 5 tests for Barrett esophagus screening. (Choices A, B, D, and E) Biomarker 3 (0.879) is more accurate than biomarker 4 (0.763); biomarker 4 is more accurate than biomarker 2 (0.758); biomarker 2 is more accurate than biomarker 5 (0.756); and biomarker 5 is more accurate than biomarker 1 (0.603). Educational objective: The accuracy of screening or diagnostic tests is quantified by the area under the ROC curve (AUC). The more accurate the test is (ie, higher sensitivity and specificity), the closer the AUC value is to 1.0. Tests with higher AUCs are more accurate than tests with lower AUCs. __________ References: Diagnostic accuracy measures. (http://www.ncbi.nlm.nih.gov/pubmed/24135733)

A Clinical Study Examines the Usefulness of 5 Different Biomarkers