External validation of the eurolung risk model for morbidity using an institutional database on minimally invasive major lung resections.

Background: The EuroLung1 model was developed by the European Society of Thoracic Surgeons (ESTS) to estimate the risk of major cardiopulmonary complications after anatomical lung resection. Because minimally invasive approaches were underrepresented in the original derivation cohort, its performance in contemporary thoracoscopic practice remains uncertain. We therefore conducted an external validation using a cohort of patients undergoing minimally invasive major lung resection. Methods: This retrospective study included 644 consecutive patients (293 females and 351 males; median age, 66 years) treated with thoracoscopic lobectomy or segmentectomy. For each patient, the EuroLung1 score was determined according to the published scoring algorithm incorporating eight weighted clinical and operative variables. Patients were subsequently categorized into the predefined risk classes. Associations between the score and major morbidity were examined, while model discrimination and calibration were evaluated using standard validation metrics. Results: The cohort included 574 lobectomies (89.1%) and 70 segmentectomies (10.9%). Histopathology revealed 548 patients (85.1%) with confirmed non-small cell lung cancer (NSCLC), 66 (10.2%) with benign disease, and 30 (4.7%) with pulmonary metastasis. Postoperative mortality and major complication rates were 0.9% and 12.9%, respectively. In logistic regression analysis, each 1-point increase in the EuroLung1 score was associated with 9% higher odds of morbidity [odds ratio (OR) =1.092, 95% confidence interval (CI): 1.010-1.180, P=0.03]. Similarly, advancing by one risk class conferred a 33% increase in the odds (OR =1.327, 95% CI: 1.027-1.715, P=0.03). Calibration analysis revealed that the EuroLung1 score underestimated morbidity risk in lower-risk classes and overestimated it in higher-risk classes. Discrimination performance of EuroLung1 score was poor, with an area under the receiver operating characteristic (ROC) curve of 0.573. Conclusions: Although the EuroLung1 score retained a significant relationship with postoperative major morbidity after minimally invasive anatomical lung resection, its predictive performance was suboptimal. The weak discrimination and variable calibration observed in this validation cohort suggest that model recalibration or revision may be necessary before application to individual risk estimation in contemporary minimally invasive thoracic surgery.