Ponce-Ponte, Oscar J.

ImportanceThyroid cancer incidence has tripled in the past 3 decades, largely driven by increased detection of small, indolent papillary thyroid cancers. Overuse of thyroid ultrasonography (TUS) contributes to overdiagnosis, leading to unnecessary biopsies, procedures, and potential patient harm.ObjectiveTo evaluate the frequency of and factors associated with inappropriate TUS (iTUS) orders and assess related clinical outcomes.Design, Setting, and ParticipantsThis retrospective cohort study analyzed adult patients 18 years and older who underwent their first TUS from January 1, 2017, to December 30, 2021, at 4 Mayo Clinic sites. Patients with previous thyroid nodule, thyroid cancer, thyroid surgery, or TUS were excluded. Based on documented clinical indications, a validated natural language processing model classified TUS orders as appropriate or inappropriate. Data were analyzed from April 2024 to May 2025.ExposuresBaseline characteristics of patients, clinicians, and clinical encounters investigated for their association with an iTUS order.Main Outcomes and MeasuresThe primary outcome was the proportion of iTUS orders. Secondary outcomes included factors associated with iTUS (sociodemographic, clinical, order-specific, and clinician-related factors) and clinical outcomes following iTUS, including the detection of thyroid nodules, thyroid procedures, and thyroid cancer diagnoses.ResultsOf 11 442 included patients, 8422 (73.6%) were female, and the mean (SD) age was 57.3 (15.8) years with a mean (SD) body mass index (calculated as weight in kilograms divided by height in meters squared) of 29.7 (7.0). Among 11 442 TUS orders, 866 (7.6%) were classified as inappropriate. In multivariable analysis, younger age (age of 18 to 54 years vs older than 65 years; odds ratio [OR], 1.86; 95% CI, 1.56-2.22), hyperthyroidism (OR, 9.04; 95% CI, 6.75-12.11), ordering by nonendocrinology specialties (eg, oncology/hematology; OR, 3.43; 95% CI, 2.47-4.76), and orders not linked to an in-person appointment (eg, portal messages; OR, 2.42; 95% CI, 2.08-2.82) were strongly associated with increased odds of iTUS. Compared with appropriate TUS, iTUS led to lower rates of thyroid nodule detection (202 of 866 [23.3%] vs 6885 of 10 576 [65.1%]; OR, 0.16; 95% CI, 0.14-0.19), biopsies (89 [10.3%] vs 2647 [25.0%]; OR, 0.34; 95% CI, 0.27-0.43), partial thyroidectomies (14 [1.6%] vs 424 [4.0%]; OR, 0.39; 95% CI, 0.23-0.67), and confirmed thyroid cancer cases (16 [1.8%] vs 425 [4.0%]; OR, 0.45; 95% CI, 0.27-0.74).Conclusions and RelevanceIn this cohort study, approximately 1 in 13 TUS orders were inappropriate. iTUS was more common in younger patients, those with thyroid dysfunction, those not seen in person, and in those referred by nonendocrinology specialties. These findings highlight the need for targeted strategies to optimize TUS use and mitigate overdiagnosis and overtreatment.

Introduction Differentiated thyroid cancer (DTC) is the most common endocrine malignancy, with a high 5-year survival rate of approximately 98%. Despite advances in diagnosis and treatment, up to 20% of patients experience recurrence, adversely affecting their quality of life. Predictive models have been developed to assess recurrence risk and guide clinical decision-making, but these models often face limitations such as retrospective design, lack of diversity in study populations and absence of external validation. The primary aim is to externally validate existing predictive models for DTC recurrence using prospective data from a diverse Latin American cohort. The secondary aim is to explore opportunities for model recalibration to improve their performance in our population. Methods and analysis The CaTaLiNA study is a multicentre prospective observational study conducted across 10 hospitals in five Latin American countries, including Ecuador, Peru, Uruguay and Mexico. Patients aged 18 years or older receiving treatment for DTC, such as the first thyroid surgery, active surveillance or radiofrequency ablation will be included. Recruitment will occur from November 2023 to June 2025, with follow-up extending until June 2028. Data collection will include baseline clinical, surgical and histological characteristics, treatment details and follow-up outcomes. Statistical analysis will follow the Transparent Reporting of a multivariable prediction model for Individual Prognosis or Diagnosis guidelines, using imputation strategies for missing data and evaluating calibration and discrimination of the prediction models. Calibration measures include the ratio of expected and observed events, calibration slope and calibration plot, while discrimination will be assessed using the C-index and area under the receiver operating characteristic curve. Ethics and dissemination This study protocol was approved by Comité de Ética de Investigación en Seres Humanos de la Universidad San Francisco de Quito USFQ ‘CEISH-USFQ’ APO-010–2023-CEIHS-USFQ Oficio No. 161-2023-CA-23030M-CEISH-USFQ. Results will be disseminated via peer-reviewed publications.