Inter-rater and Intra-rater Reliability of the Videofluoroscopic Dysphagia Scale with the Standardized Protocol

This study aimed to develop a standardized protocol for the assessment of videofluoroscopic dysphagia scale (VDS) and to demonstrate the inter-rater and intra-rater reliability of the VDS by applying the new standard protocol. A standardized protocol for the VDS was developed by dysphagia experts, including the original developer. To identify the reliability of the VDS using the protocol, 60 patients who underwent videofluoroscopic swallowing study (VFSS) for various etiologies were recruited retrospectively from three tertiary medical centers. Ten randomly selected cases were duplicated to evaluate the intra-rater reliability. Six physicians evaluated the VFSS data sets. Intraclass correlation coefficients were calculated for inter-rater and intra-rater reliability of the VDS score, and Gwet's kappa values for each VDS item were calculated. The inter-rater and intra-rater reliability of the total VDS score was 0.966 and 0.896, respectively. Notably, the evaluators' experience did not appear to have a significant impact on the reliability (physiatrists: 0.933/0.869, residents: 0.922/0.922). The reliability was consistent across different centers and dysphagia etiologies. The inter-rater and intra-rater reliability of the oral and pharyngeal sub-scores were 0.953/0.861 and 0.958/0.907, respectively. The inter-rater agreement of individual items ranged from 0.456 to 0.929, and nine items demonstrated good to very good level of agreement. Assessment of dysphagia using the VDS with the standard protocol showed excellent inter-rater and intra-rater reliabilities regardless of the evaluator's experience, VFSS equipment, and dysphagia etiologies. The VDS can be a useful assessment scale in the quantitative analysis of dysphagia based on VFSS findings.