Concordance of Three International Guidelines for Thyroid Nodules Classified by Ultrasonography and Diagnostic Performance of Biopsy Criteria

OBJECTIVE: To investigate the concordance of three international guidelines: the Korean Thyroid Association/Korean Society of Thyroid Radiology, American Thyroid Association, and American College of Radiology for thyroid nodules classified by ultrasonography (US) and the diagnostic performance of simulated size criteria for malignant biopsies. MATERIALS AND METHODS: A total of 2586 thyroid nodules (≥ 1 cm) were collected from two multicenter study datasets. The classifications of the thyroid nodules were based on three different guidelines according to US categories for malignancy risk, and the concordance rate between the different guidelines was calculated for the classified nodules. In addition, the diagnostic performance of criteria related to four different simulated biopsy sizes was evaluated. RESULTS: The concordance rate of nodules classified as high- or intermediate-suspicion was high (84.1–100%), but low-suspicion or mildly-suspicious nodules exhibited relatively low concordance (63.8–83.8%) between the three guidelines. The differences in sensitivity, specificity, and accuracy between the guidelines were 0.7–19.8%, 0–40.9%, and 0.1–30.5%, respectively, when the original biopsy criteria were applied. The differences decreased to 0–5.9%, 0–10.9%, and 0.1–8.2%, respectively, when simulated, similar biopsy size criteria were applied. The unnecessary biopsy rate calculated with the original criteria (0–33.8%), decreased with the simulated biopsy size criteria (0–8.7%). CONCLUSION: We found a high concordance between the three guidelines for high- or intermediate-suspicion nodules, and the diagnostic performance of the biopsy criteria was approximately equivalent for each simulated size criterion. The difference in diagnostic performance between the three guidelines is mostly influenced by the various size thresholds for biopsies.