Development and validation of a nomogram for predicting the need for concomitant endoscopic septoplasty during endonasal endoscopic dacryocystorhinostomy.

Background: Simultaneous endoscopic septoplasty is often required during endonasal endoscopic dacryocystorhinostomy (En-DCR) to improve access to the lacrimal sac and potentially optimize surgical success rates. In current practice, the decision to proceed to concomitant endoscopic septoplasty during En-DCR in patients with primary acquired nasolacrimal duct obstruction (PANDO) is determined by anterior rhinoscopy and nasal endoscopic examination. However, none of these methods can be used to quantitatively assess the severity of septal deviation to determine the need for concomitant endoscopic septoplasty during En-DCR. This study was thus conducted to develop and validate a radiological prediction model based on computed tomography (CT) to predict the necessity of concomitant endoscopic septoplasty during En-DCR. Methods: Data from 225 patients with PANDO and nasal septal deviation (NSD) who had undergone unilateral En-DCR in a single center from January 2022 to June 2023 were retrospectively analyzed. Least absolute shrinkage and selection operator (LASSO) was used to select predictors for concomitant endoscopic septoplasty during En-DCR. The ultimate model was developed through the application of multivariable logistic regression and subsequently confirmed through assessment with an internal validation cohort. The final model was then visually represented using a nomogram and an online calculator. Results: In this retrospective study of 225 eyes from 225 patients with PANDO and NSD, the training cohort included 157 eyes, and the validation cohort included 68 eyes. CT imaging characteristics including NSD angle [odds ratio (OR) 1.54; 95% confidence interval (CI): 1.32-1.87], NSD location (OR 4.49; 95% CI: 1.25-18.77), NSD direction (OR 5.38; 95% CI: 1.48-24.52), and middle nasal passage width (MNPW) at the surgical side (OR 0.61; 95% CI: 0.43-0.82) were identified as independent predictors for concomitant endoscopic septoplasty during En-DCR. A novel nomogram constructed from these CT signs showed high predictive performance. The area under the curves (AUCs) of the training set and internal validation set were 0.913 and 0.909, respectively. Conclusions: A CT-based radiological prediction model was created to help surgeons determine if concomitant endoscopic septoplasty is needed during En-DCR in patients with PANDO and NSD.