Page 83 - Functional impairment and cues for rehabilitation of head and neck cancer patients -

DISCUSSION
The SPEAD-test is a new timed test that evaluates an individual’s (safe) swallowing capacity for eating as well as drinking, by measuring the mean ingestion speed of three different consistencies (i.e., 100 g thin liquid, 100 g thick liquid, and a solid cream cracker). Results of this study support its safety and feasibility, with little time and money needed to perform the test. Also, assessment based on videos of the participant have proven to be reliable, enabling remote assessment in the era of telehealth. Test-retest, intra-rater and inter-rater reliability on duration measurement are good to excellent. Validity is supported by a significant difference in SPEAD-rate between HNC patients and healthy participants as well as correlations with subjective and objective swallowing outcomes. All three of the hypotheses tested to evaluate construct validity can be retained (i.e., a moderately strong to strong correlation with subjective measures, a fair to moderately strong correlation with objective measures, and a weak correlation with dyspnea, pain and fatigue).
Although two other swallowing capacity tests are currently available – the water swallow test (WST) and Test Of Masticating And Swallowing Solids (TOMASS) (19, 22) – the findings of our study indicate that the SPEAD adds clinical value. The WST was developed as a tool to screen for risk of aspiration (19). Later studies, however, have investigated the value of the WST for gaining quantitative information regarding the swallowing function (20, 21, 35). Patterson et al. (21) evaluated this test in 167 patients with HNC and found deterioration in WST outcomes (swallowing volume in mL/swallow and capacity in mL/s) from before treatment to three months after (chemo)radiotherapy and improvement afterwards. These results suggest a correlation with the degree of dysphagia, implying that the WST could indeed be used for monitoring swallowing function. After that, the TOMASS was developed as a second method of quantitative swallowing assessment by measuring the duration of solid bolus ingestion (22). The added value of the TOMASS test is that it assesses the oral preparation phase and the pressure build-up in the pharynx which is accompanied with solid bolus ingestion in contrast to thick liquid ingestion.
Yet, because they include only a single substance, both the TOMASS and the WST provide a limited assessment of overall swallowing capacity as needed in daily life. Depending on the etiology of the swallowing impairment, influenced by factors such as tumor localization, ingestion of one consistency can go without problems, while ingesting another consistency might reveal quality of life deteriorating impairment. This study showed that the SPEAD-rate better correlates with measures subjective and objective outcomes than the ingestion speed of thin liquid only and solid only. This suggests that by including the three main consistencies as ingested in daily life, the SPEAD-test provides a better bandwidth for obtaining quantitative information regarding swallowing capacity, and therefore better reflects daily functioning.
Objective swallowing measures that measure the physical function needed for swallowing, such as the VFS, do not always correlate well with the patients-reported subjective swallowing measures, which assess perceived swallowing ability and impact on functioning (16, 17). This might be, in part, because the objective measures available to date do not always include those aspects of swallowing that matters most to patients’ functioning. For example, aspiration – a
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The SPEAD-test to objectify swallowing capacity
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