Purpose: To provide normative data on swallowing capacity (mL/s) in people older than 60 years using the Timed Water Swallow Test (TWST), stratified by sex. Intra- and inter-rater reliability for swallowing time in TWST was further investigated.
Method: A total of 165 participants, aged 60 years and above, were included in the study. The time taken to consume 150 mL of tap water and the swallowing capacity (mL/s) was observed in a clinical context using the TWST. Video recordings of the performances were collected for 118 of the 165 participants for inter-rater reliability testing, of which a random set of 25 performances were assessed for intra-rater reliability. Analysis of the agreement between TWST rated by an in-person clinician and rated from a video recording was further evaluated.
Result: There were significant age and sex effects observed for swallowing capacity. The average reduction in swallowing capacity in the investigated age range (60-92 years) was 8.8 and 7.3 mL/s for women and men respectively. The results showed high inter-and intra-rater reliability and agreement between the clinical assessment and the video recording.
Conclusion: The presented measurements indicate a clear effect of age on swallowing capacity and that women may be expected to have lower capacity scores than men when tested using TWST. The provided norms can be used as reference points in the clinical identification of people at risk of dysphagia in the older population.