The main objective of this work was to determine whether the IDDSI thickness levels are sufficiently differentiated to be treated as valid therapeutic thickness levels for the treatment of dysphagia of differing severity as assessed using a validated water protocol, by establishing a correlation between IDDSI thickness levels and dysphagia grades of Water Drinking Test.

Ms. Mingsong Su and Gangying Zheng have been focusing on the study of the classification of liquids and semi-solids which frequently lead to aspiration and cough for dysphagia. The work was conducted in collaboration with Prof. Jianqin Sun and her group at Huadong Hospital in Shanghai. Ourdiet Swallow (Ourdiet, Guangzhou, China), a commercial thickener product, was used for the test. Four liquid samples of different concentrations (0.54, 1.16, 2.36, and 4.20 %) were found at the boundaries of each of levels 0, 1, 2, and 3 according to Flow Test provided by IDDSI. The shear viscosity was measured using a DHR-2 rheometer (TA Instruments, New Castle, USA) with a cone-and-plate geometry (diameter = 40 mm, angle = 2.008°). Apparent shear viscosity of sample 0.54, 1.16, 2.36, and 4.20% at 50 s-1 were determined to be 37.2, 84.1, 206.4, and 434.6 mPa•s, respectively. Altogether 26 elderly subjects were recruited and assessed for their dysphagia grades using the Water Drinking Test. Subjects were provided with a series of samples based on a modified Volume-Viscosity Swallow Test (V-VST) test and the swallowing performance (time of swallowing, number of swallows, and number of coughs) was recorded and analyzed (Fig.1).

Strong correlations among swallowing capability parameters were observed. More importantly, results from this work clearly demonstrated that severity of dysphagia with water-based swallows correlates positively with IDDSI thick-ness levels aimed at reducing dysphagia symptoms in those patients (Fig.2), confirming the reliability and feasibility of IDDSI framework for clinical applications. This work is accepted for publication in Journal of Texture Studies.