Objective: Our goal was to detect the risk factors for malignant TI-RADS 3 nodule and to construct a predictive model. Patients and Methods: All 199 patients with TI-RADS 3 nodule underwent first-time thyroid surgery from January 2018 to September 2021. Univariate analysis identified potential risk covariates and then incorporated these covariates into multivariate logistic regression to determine the risk factors for malignant TI-RADS 3 nodule and construct a predictive model. Results: Binary logistic regression analysis showed that age [odds ratio (OR): 0.926, 95% CI: 0.865-0.992; P = .029), low level of parathyroid hormone (OR: 0.940, 95% CI: 0.890-0.993; P = .027), and preoperative ultrasound features of TI-RADS 3 nodule, such as echogenicity (OR: 8.496, 95% CI: 1.377-52.406; P = .021), echogenic foci (OR: 8.611, 95% CI: 1.484-49.957; P = .016), and maximum tumor diameter (OR: 0.188, 95% CI: 0.040-0.888; P = .035) were independent risk factors for malignant TI-RADS 3 nodule. Based on these independent risk factors, a logistic regression model was established. The area under curve of the prediction model for TI-RADS 3 thyroid cancer was 0.921 (95% CI: 0.856-0.986, P < 0.001). The maximum Youden index was 0.698. The cut-off value, sensitivity, and specificity were 0.074, 84.6%, and 85.2%, respectively. Conclusion: Young age, iso/hypo/very hypo echo, echogenic foci, nodule diameter <30 mm, and low level of PTH are independent risk factors for TI-RADS 3 thyroid carcinomas. This prediction model has a high sensitivity and specificity. A prediction model value of more than 0.074 implies that the TI-RADS 3 nodule has undergone a malignant transformation, and fine needle aspiration is recommended in these cases.
Keywords: TI-RADS 3; predictive model; retrospective study; thyroid carcinoma; thyroid nodule.