Dynamic Imaging Grade of Swallowing Toxicity (DIGEST): Scale development and validation

Area of Science:

• Oncology
• Radiology
• Speech-Language Pathology

Background:

• The National Cancer Institute's Common Terminology Criteria for Adverse Events (CTCAE) is standard for toxicity reporting in oncology.
• Pharyngeal dysphagia is a critical toxicity endpoint in head and neck cancer (HNC) organ-preservation trials.
• A standardized, CTCAE-compatible grading system for dysphagia is needed.

Purpose of the Study:

• To develop and validate a CTCAE-compatible modified barium swallow (MBS) grade for pharyngeal dysphagia in HNC.
• To hypothesize that a 5-point MBS grade (DIGEST) would be feasible and psychometrically sound.

Main Methods:

• A modified Delphi exercise was used for content validation and expert consensus on DIGEST criteria.
• Two blinded raters assessed 100 MBS studies.
• Intrarater and interrater reliability were tested using weighted kappa (κ) values.
• Criterion validity was assessed against established measures of swallowing function and patient-reported outcomes.

Main Results:

• Excellent intrarater reliability (κ = 0.82-0.84) and substantial to almost perfect interrater reliability (κ = 0.67-0.81) were achieved.
• DIGEST significantly correlated with pharyngeal pathophysiology (MBSImP™©, r=0.77), swallow efficiency (OPSE, r=-0.56), perceived dysphagia (MDADI, r=-0.41), and oral intake (PSS-HN, r=-0.49).
• All correlations were statistically significant (P < .0001).

Conclusions:

• The Dynamic Imaging Grade of Swallowing Toxicity (DIGEST) adapts MBS ratings to CTCAE nomenclature for ordinal toxicity grading.
• DIGEST is a psychometrically sound measure for HNC clinical trials.
• DIGEST can be used to investigate toxicity profiles, dose responses, and predictive modeling in HNC treatment.