Validation of the Swedish Dynamic Imaging Grade of Swallowing Toxicity for Flexible Endoscopic Evaluation of Swallowing (DIGEST-FEES)

In the head and neck cancer (HNC) population around 45% suffer from chronic swallowing difficulties after cancer treatment. Previously a measure for flexible endoscopic evaluation of swallowing (FEES) where swallowing efficiency, safety and overall ability is evaluated within the same framework has been lacking. The Dynamic Imaging Grade of Swallowing Toxicity for FEES (DIGEST-FEES) was developed in 2021 and provides such a measure for patients with HNC. The aim of this study was to translate and validate the DIGEST-FEES into Swedish (Sw-DIGEST-FEES). A translation of the protocol to Swedish was done through forward-backward translation. Two raters rated eighty-nine FEES recordings according to the Sw-DIGEST-FEES and five reference measures of swallowing ability: Yale Pharyngeal Residue Severity Rating Scale, Swallowing Performance Scale, Murray Secretion Scale, MD Anderson Dysphagia Inventory and Penetration Aspiration Scale. Intra- and interrater reliability was analyzed. Construct validity was evaluated by correlating the Sw-DIGEST-FEES ratings to the reference measures. A priori hypothesis was that the correlations would correspond to those of the reference measures included in the original English version. The Sw-DIGEST-FEES demonstrated retained psychometric properties. Construct validity was good. 79% of correlations to the reference measures were equal to or stronger than those in the original development. Inter-rater agreement of the Sw-DIGEST-FEES ranged from substantial to almost perfect (0.76-0.81). Intra-rater reliability was in general almost perfect (0.8-1). The Sw-DIGEST-FEES can be considered a valid and reliable protocol for use in evaluation of swallowing function in HNC patients.