This study analyzed the effect that dysphagia etiology, different observers, and bolus consistency might have on the level of agreement for measurements in FEES images reached by independent versus consensus panel rating. Sixty patients were included and divided into two groups according to dysphagia etiology: neurological or head and neck oncological. All patients underwent standardized FEES examination using thin and thick liquid consistencies. Two observers scored the same exams, first independently and then in a consensus panel. Four ordinal FEES variables were analyzed. Statistical analysis was performed using a linear weighted kappa coefficient and Bayesian multilevel model. Intra- and interobserver agreement on FEES measurements ranged from 0.76 to 0.93 and from 0.61 to 0.88, respectively. Dysphagia etiology did not influence observers' agreement level. However, bolus consistency resulted in decreased interobserver agreement for all measured FEES variables during thin liquid swallows. When rating on the consensus panel, the observers deviated considerably from the scores they had previously given on the independent rating task. Observer agreement on measurements in FEES exams was influenced by bolus consistency, not by dysphagia etiology. Therefore, observer agreement on FEES measurements should be analyzed by taking bolus consistency into account, as it might affect the interpretation of the outcome. Identifying factors that might influence agreement levels could lead to better understanding of the rating process and assist in developing a more precise measurement scale that would ensure higher levels of observer agreement for measurements in FEES exams.
Keywords: Deglutition; Deglutition disorder; Fiberoptic endoscopic evaluation of swallowing (FEES); Observer agreement.