Diagonal Earlobe Crease (Frank's Sign) for Diagnosis of Coronary Artery Disease: A Systematic Review of Diagnostic Test Accuracy Studies

Coronary artery disease is a global challenge for healthcare systems. Early diagnosis is a key issue to improve quality of life and reduce morbidity and mortality. Diagonal earlobe crease, a wrinkle extending obliquely across the earlobe, was linked by many authors to various atherosclerotic diseases. This systematic review aimed at summarizing the diagnostic accuracy of diagonal earlobe crease for diagnosis of chronic and acute coronary syndromes in adults. Cochrane's recommendations for systematic reviews of diagnostic test accuracy studies were followed. The protocol was registered on PROSPERO. Seven electronic databases were searched up to April 2021. The risk of bias and applicability were assessed using the QUADAS-2 tool. Meta-analysis was not performed. Finally, 13 cross-sectional studies evaluating 3951 patients were analyzed, all of which focused on chronic coronary syndromes defined as anatomically significant coronary stenosis. Invasive coronary angiography was used as a reference in most studies, except one which utilized computed tomography angiography. Sensitivity ranged from 26% to 90%, and specificity from 32% to 96%. Positive likelihood ratios varied from 1.11 to 7.03, but most results were below 2. Negative likelihood ratios were from 0.84 to 0.30, but most values exceeded 0.5. Diagnostic accuracy of diagonal earlobe crease for the detection of chronic coronary syndromes is insufficient. It only slightly changes pre-test probability, and its mere presence or absence should not affect the clinical management of the patients. However, for its feasibility and easy interpretation, Frank's sign could be considered as a part of physical examination.