OBJECTIVE The influence of age on the malignant cytology rate of thyroid nodules remains uncertain. The American College of Radiology - Thyroid Imaging Reporting and Data System (ACR TI-RADS) is currently used to guide subsequent investigations of thyroid nodules, regardless of clinical variables. This study aimed to investigate the impact of age on the malignant cytology rates of thyroid nodules and the diagnostic performance of ACR TI-RADS across different age groups. DESIGN Retrospective, single-center, observational study. METHODS Patients aged ≥ 20 years with thyroid nodules, who underwent fine-needle aspiration biopsy between 2012 and 2019 were evaluated. Ultrasound images were used to obtain the TI-RADS data. Malignancy was determined based on suspicious for malignancy (Bethesda V) and malignant (Bethesda VI) cytology results or malignancy in cell block analysis. RESULTS A total of 1,023 nodules from 921 patients (88.2% female) were analyzed. The median age was 58.5 (IQR, 41.1-66.6) years, and the median nodule size was 2.4 (IQR, 1.7-3.6) cm. Stratification by age revealed a decreasing prevalence of malignant cytology across subgroups of 20-39, 40-59, and ≥60 years (10.7%, 8.5%, and 3.7%, respectively; P = 0.002). After adjusting for sex, multinodularity, nodule size, and ACR TI-RADS category, we observed that each year of age reduced the OR for malignant cytology by 3.0% (95% confidence interval: 0.7-5.3%; P = 0.011). When comparing the subgroups of 20-39 and ≥60 years, the malignant cytology rate decreased by half in TI-RADS 4 (from 21.4% to 10.4%) and two-thirds in TI-RADS 5 (from 64.7% to 22.6%). CONCLUSIONS Our study demonstrated that, as patient age increased, the rate of malignant cytology in thyroid nodules decreased. Moreover, age significantly influences the malignancy rates of thyroid nodules classified according to the ACR TI-RADS.

中文翻译：

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甲状腺结节恶性细胞学发生率与年龄相关的变化：评估 ACR TI-RADS 的回顾性观察研究的见解。

目的年龄对甲状腺结节恶性细胞学发生率的影响尚不确定。美国放射学会 - 甲状腺成像报告和数据系统 (ACR TI-RADS) 目前用于指导甲状腺结节的后续研究，无论临床变量如何。本研究旨在探讨年龄对不同年龄组甲状腺结节恶性细胞学发生率的影响以及ACR TI-RADS诊断性能的影响。设计 回顾性、单中心、观察性研究。方法对2012年至2019年间接受细针穿刺活检的年龄≥20岁的甲状腺结节患者进行评估。超声图像用于获取 TI-RADS 数据。根据可疑恶性肿瘤 (Bethesda V) 和恶性 (Bethesda VI) 细胞学结果或细胞块分析中的恶性肿瘤来确定恶性肿瘤。结果 共分析了 921 名患者（88.2% 为女性）的 1,023 个结节。中位年龄为 58.5（IQR，41.1-66.6）岁，中位结节大小为 2.4（IQR，1.7-3.6）cm。按年龄分层显示，20-39、40-59 和 60 岁以上亚组的恶性细胞学患病率呈下降趋势（分别为 10.7%、8.5% 和 3.7%；P = 0.002）。在调整性别、多结节性、结节大小和 ACR TI-RADS 类别后，我们观察到，每年龄增长，恶性细胞学的 OR 就会降低 3.0%（95% 置信区间：0.7-5.3%；P = 0.011）。比较20-39岁和≥60岁的亚组时，TI-RADS 4中的恶性细胞学发生率下降了一半（从21.4％降至10.4％），TI-RADS 5中下降了三分之二（从64.7％降至22.6％） 。结论 我们的研究表明，随着患者年龄的增加，甲状腺结节的恶性细胞学发生率下降。此外，年龄显着影响根据 ACR TI-RADS 分类的甲状腺结节的恶性率。