Comparison of different systems of ultrasound (US) risk stratification for malignancy in elderly patients with thyroid nodules. Real world experience

To comparatively assess the performance of three sonographic classification systems, American Thyroid Association (ATA), the American College of Radiology Thyroid Imaging Reporting and Data System (ACR TI-RADS), and American Association of Clinical Endocrinologists (AACE)/American College of Endocrinology (ACE)/Associazione Medici Endocrinologi (AME) in identifying malignant nodules in an elderly population. Methods: Cross-sectional study of patients referred for fine needle aspiration biopsy in an academic center for the elderly. One nodule/patient was considered. Nodules classified Bethesda V/VI were considered malignant. Receiver operating characteristics (ROC) curves were established and compared to evaluate diagnostic performance. Malignancy among biopsies below the size cutoff for each ultrasound classification was also compared. Results: One thousand, eight hundred sixty-seven patients (92% females); median (Q1-Q3), age 71 (67-76) years, were studied showing 82.8% benign (Bethesda II) and 2.6% malignant cytology. The three classifications correctly identified malignancy (P < 0.01). Nonetheless, in the ATA and AACE/ACE/AME 16 and 2 malignant nodules, respectively, were unclassifiable. Including unclassified malignant nodules (n = 1234, malignant = 50), comparison of the ROC curves showed lower performance of ATA [area under the curve (AUC) = ATA (0.49) vs. ACR TI-RADS (0.62), p = 0.008 and ATA vs. AACE/ACE/AME (0.59), p = 0.022]. Proportion of below size cutoff biopsies for ATA, ACR TI-RADS, and AACE/ACE/AME was different [16, 42, and 29% (all p < 0.001)], but no differences in malignancy rate were observed in these nodules. Conclusion: The present study is the first to validate in elderly patients these classifications showing that AACE/ACE/AME and ACR TI-RADS can predict thyroid malignancy more accurately than the ATA when unclassifiable malignant nodules are considered. Moreover, in this aged segment of the population, the use of ACR TI-RADS avoided more invasive procedures. Keywords: Elderly patients; Malignant cytology; Thyroid nodules; Ultrasound characteristics.