The Criteria of Thickened Liquid for Dysphagia Management in Japan

In Japan, the viscosity of thickened liquids is different among hospitals and nursing homes. In order to standardize viscosity of thickened liquids, the dysphagia diet committee of the Japanese Society of Dysphagia Rehabilitation developed the Japanese Dysphagia Diet 2013 (JDD2013). To decide on a definition of thickened liquids, the committee reviewed categories from other countries. Especially, the criteria of the USA and Australia were used as references. The definition had three levels: mildly thick, moderately thick, and extremely thick. Then a sensory evaluation by health care workers was carried out to decide the viscosity range of each level, and a draft document was made. After collecting public comments, follow-up experiments using thickened water with thickeners using xanthan gum were performed, and the JDD2013 (Thickened Liquid) was determined. The JDD2013 (Thickened Liquid) evaluated the drinking properties, visual properties, and viscosity values of each level. The shear rate of 50 s⁻¹ was adopted to measure the viscosity with a cone and plate type viscometer to duplicate the measurement criteria used by the USA. We also set the values of the JDD2013 with the Line Spread Test to promote the use of guidelines in clinical practice. We believe the JDD2013 standards help hospitals and other settings that care for people with dysphagia to use the same thickness level and the same labels. In the future, the JDD2013 levels will be compared with new international guidelines to help with international understanding of the JDD2013 levels.