A Prognostic Nomogram model for Non-complete remission following initial radioiodine therapy in Graves' hyperthyroidism

Congcong Wang^1*Yutian Li²Guohua Qin¹Yanhui Song¹Xue Yang¹Yaqi Lu¹Xufu Wang^1*

• ¹The Affiliated Hospital of Qingdao University, Qingdao, China
• ²Qingdao Women and Children's Hospital, Qingdao, China

Background: Radioiodine (RAI) therapy, while established for Graves' hyperthyroidism (GH), exhibits variable efficacy (50-80% cure rates), with non-complete remission (NCR) necessitating retreatment. In the study, we aimed to identify independent predictors of NCR and develop a validated nomogram for personalized RAI outcome prediction. Methods: Data from 285 GH patients undergoing initial RAI therapy were retrospectively analyzed and randomly allocated into training (n=199) and validation (n=86) cohorts at a 7:3 ratio. Univariate followed by multivariate logistic regression identified independent predictors of NCR in the training cohort. These variables informed the construction of a prognostic nomogram model, subsequently verified in the validation cohort through calibration, receiver operating characteristic (ROC) curve, and decision curve analysis (DCA) to assess model reliability, discriminative ability, and clinical utility. Results: Thyroid mass (TM), 24-hour RAI uptake (RAIU24h), effective half-life (Teff), and free triiodothyronine reduction at 1-month post-therapy (ΔFT3) were independent predictors. The prognostic nomogram integrating these variables exhibited superior discriminative performance in both training (AUC=0.919) and validation cohorts (AUC=0.901). Calibration curves confirmed high fidelity between predicted and observed NCR probabilities. DCA demonstrated significant clinical net benefit across threshold probabilities. Conclusion: TM, RAIU24h, Teff, and ΔFT3 are critical determinants of RAI efficacy