Abstract
Objective swallowing outcomes measure the physical swallowing function, while subjective outcomes measure swallowing perception. A test for swallowing capacity, measuring the ingestion of all consistencies is currently not available. Therefore, the Swallowing Proficiency for Eating And Drinking (SPEAD) test was developed. It entails the timed ingestion of thin liquid, thick liquid and solid. In this study, its feasibility, reliability and validity were evaluated in patients with dysphagia after treatment for head and neck cancer (HNC) and healthy participants. Thirty-eight HNC patients and forty healthy participants were enrolled in this study and performed the SPEAD test three times. Video recordings of the test were evaluated three times by one observer, and once by three additional observers, to assess test-retest, intra-rater and inter-rater reliability. Validity was assessed by calculating effect sizes for the difference between results of patients and healthy participants and by evaluating correlations with objective (e.g., videofluoroscopy and functional oral intake scale) and subjective (e.g., SWAL-QOL) swallowing outcomes. Test-retest, intra-rater and inter-rater reliability of ingestion duration was good to excellent. All hypotheses with regard to magnitude and direction of correlations were confirmed, supporting construct validity of the test. Our initial results suggest that the SPEAD test reliably measures the transport capacity of the upper digestive tract (in grams per second) and that this test can be useful to objectively evaluate and monitor the (safe) swallowing capacity in HNC patients, in both research as well as daily clinical practice.