Development and content validation of the ultrasound swallowing assessment protocol for adults and older adults (USAP)

Content validity is a central component in the development and evaluation of health measurement instruments, as it ensures that the domains, items, and instructions adequately, comprehensively, and comprehensibly represent the construct to be measured. Heterogeneous ultrasound parameters for assessing swallowing, anatomical landmarks, and analytical criteria reinforce the need for standardized instruments that systematically guide what can be assessed, how images can be acquired and analyzed, and how findings can be interpreted. Thus, this study aimed to develop the Ultrasound Swallowing Assessment Protocol (USAP) and obtain evidence of its content validity for the assessment of swallowing in adults and older adults. The protocol items were initially developed based on evidence identified in a previously published scoping review, which included 73 studies on ultrasound assessment of swallowing. The initial version was submitted to 10 expert judges for quantitative content validity assessment, addressing comprehensibility, relevance, pertinence, and comprehensiveness, with an open field for comments and suggestions. Based on the quantitative results and qualitative feedback, the protocol was subsequently revised and discussed in three online consensus meetings with the judges, during which additional modifications were incorporated into the final version. The USAP provides guidance on patient and setting preparation, ultrasound image acquisition, evaluated regions, and analyzed parameters, including morphometric and kinematic measures of the oral muscles and tongue, hyoid bone displacement, hyoid–larynx approximation, and assessment of the laryngopharyngeal region. The USAP items were judged relevant, pertinent, comprehensible, and comprehensive by an expert panel. Further studies are needed to establish its technical and operational reproducibility and other measurement properties before broader clinical implementation.