Predictors of Improvement of R-EBUS Findings From “Adjacent To” to “Within” in EBUS-GS: A Retrospective Cohort Study

Abstract

Background: In flexible bronchoscopy, endobronchial ultrasonography using a guide sheath (EBUS-GS) has varying diagnostic yields depending on the findings of radial-endobronchialultrasonography (R-EBUS). The diagnosis rate is lower when R-EBUS lesions are “adjacent to,” than when they are “within.” However, these findings are inconsistent and may change from “adjacent to” to “within” as the examination progresses (referred to as A to W). In this study, we analyzed the predictive factors for this change, which remain unexplored. Methods: This retrospective cohort study included patients who underwent flexible bronchoscopic biopsy with EBUS-GS at Kameda Medical Center between April 2014, and March 2019. Patients without “adjacent to” lesions were excluded. Based on multivariate regression results by drawing a receiver operating characteristic curve, we evaluated the discrimination properties of factors strongly correlated with “A to W”. Results:In total, 261 patients were included in this study. In 84 cases, R-EBUS findings were “adjacent to” to “within,” while in 177 cases, they were not. The mean lesion diameter was significantly larger (p = 0.021) in the group with “A to W” than in the group without it. The odds ratio (OR) for lesion diameter was significant in the multivariable regression model (OR: 1.024 [1.003-1.046]). The sensitivity and specificity were 0.346 and 0.853, respectively, at the optimal threshold (29.25 mm) set using the Youden index. Conclusion: In this study, we found that lesion diameter was a significant factor in predicting “A to W,” indicating a cutoff value of 29.25 mm with high specificity (0.853). Trial registration: The participants were registered retrospectively.