Objective Head and neck radiotherapy (RT) is associated with an increased risk of carotid artery stenosis; yet standardized surveillance guidelines for nasopharyngeal carcinoma (NPC) survivors remain lacking. This study aimed to develop a risk prediction model to identify individuals at heightened risk.

Methods We conducted this retrospective cohort study using claims data from the National Taiwan University Hospital-integrative Medical Database (NTUH-iMD). A Cox-based prediction model using stepwise variable selection was developed and model performance was evaluated using the area under receiver operating characteristic (ROC) curre (AUC) and integrated Brier score (IBS). To identify the optimal timing for initiating carotid ultrasound screening in post-RT NPC patients, a multivariable Generalized Linear Mixed Model (GLMM) was used to determine the post-treatment year most strongly associated with the development of moderate or greater internal carotid artery (ICA) stenosis.

Results Patients in the high-risk group (risk score≥5) have significantly increased risk of moderate or greater ICA stenosis, which may begin to manifest as early as the fourth year after receiving radiation therapy. Additionally, we found that, compared to the average risk of the entire cohort, the risk of developing moderate-to-severe ICA stenosis began to increase significantly and persistently around the seventh year after radiotherapy. Moreover, the model achieved an AUC of 0.623 and an IBS of 0.084, indicating moderate discriminatory ability and good overall predictive accuracy.

Conclusion According to our proposed risk prediction model, we recommend that carotid ultrasound screening begin in the seventh year following radiation therapy, while high-risk patients should start screening earlier, beginning in the fourth year.

The authors have declared no competing interest.

nil

nil

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

Research Ethics Committee of NTUH and complied with the Declaration of Helsinki (approval number: 202403116RINE)

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

Yes

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

Yes

I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

Yes