The Canada Lymph Node Score for prediction of malignancy in mediastinal lymph nodes during endobronchial ultrasound.

Abstract

During endobronchial ultrasound (EBUS) staging, ultrasonographic features can be used to predict mediastinal lymph node (LN) malignancy. We sought to develop the Canada Lymph Node Score a tool capable of predicting LN metastasis at the time of EBUS. Patients undergoing EBUS staging for lung and esophageal cancer were prospectively enrolled. Features were identified in real time by an endoscopist and video-recorded. Videos were sent to raters. Pathologic specimens from biopsies/surgical resections were used as the gold-standard reference test. Logistic regression, receiver operator characteristic curve, and Gwet's AC1 analyses were used to test the performance, discrimination, and inter-rater reliability, respectively. In total, 300 LNs from 140 patients were analyzed by 12 endoscopists (raters) across 7 Canadian centers. Beta-coefficients from a multivariate regression model were used to create a 4-point score: short-axis diameter, margins, central hilar structure, and necrosis. The model showed good discriminatory power (c-statistic = 0.72 ± 0.04, 95% confidence interval [CI], 0.64-0.80; bias-corrected c-statistic: 0.66, 95% CI, 0.55-0.76). LNs scoring 3/4 or 4/4 had odds ratios of 15.17 (P < .0001) and 50.56 (P = .001) for predicting malignancy, respectively. Inter-rater reliability for a score ≥3 was 0.81 ± 0.02 (95% CI, 0.77-0.85). The Canada Lymph Node Score is a 4-point score demonstrating excellent performance in identifying malignant LNs during EBUS. A cut-off of ≥3 may inform decision-making regarding biopsy, repeat biopsy, or mediastinoscopy if the initial results are inconclusive.