Agreement Between American and European Thyroid Imaging, Reporting, and Data System (TIRADS) in the Diagnosis of 473 Thyroid Nodules From a Single Center in Brazil

Objective To compare 2 ultrasound-based risk stratification systems in malignancy risk assessment of thyroid nodules and the clinical applicability of these guidelines in Brazil. Methods We retrospectively reviewed the ultrasound findings of 314 patients (473 thyroid nodules) who underwent fine-needle aspiration (FNA) biopsy and/or surgery between February 2018 and March 2019. All nodules were classified using 2 systems: the Thyroid Imaging, Reporting, and Data System (TIRADS) of the American College of Radiology (ACR-TIRADS) and the TIRADS of the European Thyroid Association (EU-TIRADS). Both risk stratification systems were analyzed. We identified the diagnostic predictive values that yielded optimal sensitivity, specificity, positive predictive value, negative predictive value, and accuracy. Results Of the 473 nodules, all underwent FNA, and histopathology was performed for 332 nodules. The agreement between the ACR-TIRADS and EU-TIRADS results and that between cytology and histopathology findings was 92.6% (kappa = 0.84) and 86.7% (kappa = 0.73), respectively. The area under the curve for the ACR-TIRADS and EU-TIRADS was 0.871 and 0.828, respectively (P < .001). The EU-TIRADS had the best sensitivity and negative predictive value, whereas the ACR-TIRADS had the best specificity, positive predictive value, and accuracy. Of the 473 nodules studied, only 158 (33.4%) followed the FNA size criteria suggested by the ACR-TIRADS. Conclusion ACR-TIRADS and EU-TIRADS had good diagnostic performances. However, most aspirated nodules did not follow the TIRADS indication; thus, the overuse of FNA as a diagnostic tool was observed.