Transcultural Adaptation and Validation of the German DIGEST-FEES

Flexible endoscopic evaluation of swallowing (FEES) is one of two diagnostic gold standards for pharyngeal dysphagia in patients with head and neck cancer (HNC). However, an evidence-based summary outcome measure was missing until recently. The Dynamic Imaging Grade of Swallowing Toxicity (DIGEST) for FEES was adapted from DIGEST_V2 for videofluoroscopy for this purpose and is a validated analysis method, grading the severity of pharyngeal dysphagia based on the swallowing parameters safety and efficiency. Main aim of this study was to translate and validate DIGEST-FEES into German (DIGEST-FEES-G).

First, the transcultural translation included forward and backward translations, cognitive interviews, and consensus in an expert committee together with the original developers. Subsequently, the 100 endoscopic examination videos of the DIGEST-FEES original validation study were retrospectively analyzed with DIGEST-FEES-G.

After a training phase, inter-rater reliability was almost perfect for overall DIGEST-FEES-G grade (Kw = 0.89), DIGEST-FEES-G safety (Kw = 0.9), and DIGEST-FEES-G efficiency (Kw = 0.88). Intra-rater reliability for the DIGEST-FEES-G rating was almost perfect (rater 1: Kw = 0.81-0.88) and substantial to almost perfect (rater 2: Kw = 0.78-0.92). Overall DIGEST-FEES-G grade correlated with the German Murray Secretion Scale (r = 0.47; p < 0.01), German Yale Vallecular Residue (r = 0.74; p < 19 0.01), and German Yale Pyriform Sinus Residue (r = 0.66; p < 0.01).

The validation and reliability findings of the original study could be replicated for DIGEST-FEES-G which increases validity of the DIGEST-FEES scale. The translated version, DIGEST-FEES-G, provides a psychometrically sound analysis method for the severity grading of pharyngeal dysphagia in HNC for German-speaking practitioners.