Comparison and preliminary discussion of the reasons for the differences in diagnostic performance and unnecessary FNA biopsies between the ACR TIRADS and 2015 ATA guidelines.

Objectives: (1) To compare the American College of Radiology (ACR) thyroid imaging reporting and data system (TIRADS) and American Thyroid Association (ATA) guidelines for thyroid nodules with regard to diagnostic performance and effectiveness at reducing the number of fine-needle aspiration (FNA) biopsies and to preliminarily discuss the reasons for the differences and (2) to compare the diagnostic performance of the two guidelines in the subgroup of nodules <1 cm in diameter.
Materials and Methods: In the present study, 1000 thyroid nodules in 894 consecutive patients with final diagnoses were included; these thyroid nodules were investigated via FNA biopsies in our hospital. The ultrasound (US) features of the thyroid nodules were reviewed and stratified according to the categories defined by the ACR TIRADS and ATA guidelines.
Results: Compared with the ACR TIRADS guidelines, the ATA guidelines had a higher sensitivity (93.4% (P < 0.001)) and a larger negative predictive value (NPV) (85.3% (P= 0.034)). Compared with the ATA guidelines, the ACR TIRADS guidelines had a higher specificity (66.0% (P < 0.001)), a greater PPV (73.6% (P= 0.001)), and greater accuracy (75.5% (P= 0.017)). Compared with the ATA guidelines, the ACR TIRADS guidelines resulted in significantly fewer unnecessary FNA biopsies (P= 0.007).
Conclusions: This study suggests that both the ACR TIRADS and ATA guidelines have unique strengths with regard to their diagnostic performance. In terms of reducing the number of FNA biopsies, the ACR TIRADS guidelines were superior to the ATA guidelines.