Considering that measurement is a critical part of diagnostic technique for evaluating swallowing dysfunction, there is a need for a better foundational understanding of what influences residue measurement on flexible endoscopic evaluation of swallowing (FEES). This study investigated two factors and their potential influence on trends in residue ratings on FEES: (1) bolus consistency, and (2) residue severity levels on two different types of rating scales. Thirty-three clinicians were asked to rate their overall impressions of pharyngeal residue on 75 FEES videos representing a wide range of residue severities for thin liquid, applesauce, and cracker boluses. Ratings were made on both a visual analog scale (VAS) and a five-point ordinal scale in a randomized fashion across two sessions about two weeks apart. Statistical correlations were determined to assess the association between residue ratings and severity levels and bolus consistency. A total of 2475 VAS ratings and 2473 ordinal ratings were collected. Residue ratings were statistically different depending on severity level (p < 0.0001) and bolus consistency (p < 0.004). Raters appeared to avoid rating at the severe end of the scales, especially on visual analog scales. This study documented the relationship between clinician ratings of pharyngeal residue on FEES and various factors like severity and bolus type. Other findings, such as differences in ratings depending on the type of rating scale and halo effects on the VAS, are valuable for future scale development for understanding perceptual ratings of residue on FEES.
Keywords: Deglutition; FEES; Pharyngeal residue.