Rethinking residue, an investigation of pharyngeal residue on flexible endoscopic evaluation of swallowing: the past, present, and future directions

Abstract

This dissertation investigated measures of pharyngeal residue as seen on flexible endoscopic evaluation of swallowing (FEES). Research in this area of deglutology has been stalled due to measurement problems. The particular aims of this project were to compare visual analog scale ratings to categorical ratings of residue on FEES, and to investigate various measurement aspects. METHODS: Speech language pathologists were asked to rate residue from 81 swallows on FEES that demonstrated a wide range of residue severity for thin liquid, applesauce, and cracker boluses. A total of 33 clinicians rated the amount of residue at the time point after the first swallow, twice in a randomized fashion: the first time on a visual analog scale (VAS) and the second time categorically on a five point Likert scale. The results were analyzed for (1) inter/intra-rater agreement, (2) correlations between ratings and residue severity for each rating method, and (3) clusters of ratings to better define the scales and their clinical significance. A total of 2,673 VAS ratings and 2,673 categorical ratings were collected. RESULTS: (1) Both inter- and intra-rater reliability met acceptable levels of agreement, although intra-rater reliability on VAS ratings were slightly higher (r=0.8–0.9) than categorical ratings (k=0.7–0.8). Expert ratings were not significantly different from other clinicians’ ratings for any severity of any of the 3 boluses. (2) Residue ratings fit best on a curvilinear model; a quadratic fit of the data significantly improved the r2 values for each bolus type. (3) An increased residue amount, rated on either the VAS or categorical scale, was significantly associated with worse penetration-aspiration scale scores, but no significant relationship was found between the two methods of residue ratings and measures of quality of life or diet. Novel computerized methods are proposed for future measurement pursuits. CONCLUSION: The results of this dissertation suggest that residue is best measured on a scale with unequal intervals, and clinicians can be reliable in rating overall amount of residue on FEES after the first swallow. Novel computerized measurement approaches are useful building blocks for future research. It is hoped that with better measurement will come better understanding of residue, its risks, and consequences