Supplementary Material for: Characterizing the Validity of Using VASES to Derive DIGEST-FEES Grades

Introduction: Visual Analysis of Swallowing Efficiency and Safety (VASES) and Dynamic Imaging Grade of Swallowing Toxicity for Flexible Endoscopic Evaluation of Swallowing (DIGEST-FEES) are two complimentary methods for assessing swallowing during FEES. Whereas VASES is intended to facilitate trial level ratings of pharyngeal residue, penetration, and aspiration, DIGEST-FEES is intended to facilitate protocol level impairment grades of swallowing safety and efficiency. The aim of this study was to assess the validity of using VASES to derive DIGEST-FEES impairment grades.

Methods: DIGEST-FEES grades were blindly analyzed from 50 FEES – first using the original DIGEST-FEES grading method (n = 50) and then again using a VASES-derived DIGEST-FEES grading method (n = 50). Weighted Kappa (κw), and absolute agreement (%) were used to assess the relationship between the original DIGEST-FEES grades and VASES-derived DIGEST-FEES grades. Spearman’s correlations assessed the relationship between VASES-derived DIGEST-FEES grades with measures of construct validity.

Results: Substantial agreement (κw = 0.76 – 0.83) was observed between the original and VASES-derived grading methods, with 60-62% of all DIGEST-FEES grades matching exactly, and 92-100% of DIGEST-FEES grades within one grade of each other. Furthermore, the strength of the relationships between VASES-derived DIGEST-FEES grades and measures of construct validity (r = 0.34–0.78) were similar to the strength of the relationships between original DIGEST-FEES grades and the same measures of construct validity (r = 0.34–0.83).

Discussion/Conclusion: Findings from this study demonstrate substantial agreement between original and VASES-derived DIGEST-FEES grades. Using VASES to derive DIGEST-FEES also appears to maintain the same level of construct validity established with the original DIGEST-FEES. Therefore, clinicians and researchers may consider using VASES to increase the transparency and standardization of DIGEST-FEES ratings. Future research should seek to replicate these findings and to explore the simultaneous use of VASES and DIGEST-FEES in a greater sampling of raters and across other patient populations.