Reliability, validity and normative data of the timed water swallow test accompanied by sEMG.

Purpose: Swallowing disorders are highly interrelated with increased morbidity and mortality rates; therefore, early detection is crucial. Most screening tools rely on subjective observation, thus making objective assessment tools more vital. Timed Water Swallowing Test (TWST) is a screening tool used in the field providing quantitative data. This study aimed to investigate the swallowing parameters in a wide age range by using TWST and to expand the already existing normative data pool accordingly. It is also aimed to examine the reliability of the TWST and assess its validity in stroke survivors.

Materials and methods: This study had a cross-sectional design. TWST carried out simultaneously along with surface EMG and laryngeal sensor on 196 healthy subjects aged 10 to 80 for normative data. Also, TWST carried out 30 patients having a history of recent stroke. Test-retest and inter-rater scoring analysis were used for reliability purposes, while Gugging Swallowing Screen (GUSS) test was used for validity purposes. Additionally, the correlations between the participants' TWST scores and GUSS scores were examined using the Spearman correlation coefficient.

Results: The normative TWST data of healthy participants are tabulated and presented and their average swallowing capacity was found 13.73 ml/s. Furthermore, the mean swallowing capacity of stroke survivors was found 4.61 ml/s. As a result of validity analyses, a statistically strong and significant relationship was found between GUSS and TWST parameters (r = 0.775, p < 0.001). Intraclass correlation coefficient (ICC) and correlation values were found between moderate to good agreement between test-retest measurement (ICC = 0.563 to 0.891, p < 0.05). Also, the agreement between the raters was found to be significant (ICC = 0.949 to 0.995, p < 0.05).

Conclusion: TWST is a valid and reliable screening tool to evaluate dysphagia on given population. Although the test's performance on healthy individuals is adequate, more research is still needed to confirm that it can be used as a screening tool for stroke.