Oral diadochokinesis is related to decline in swallowing function among community-dwelling Japanese elderly: a cross-sectional study

Background: Since oral organs function in the first stage of the swallowing process, it is possible that decline in swallowing function can be partly related to oral frailty. Aims: The purpose of this study was to investigate the association between swallowing function and oral function among community-dwelling elderly Japanese and to propose cut-off values for screening of decline in swallowing function. Methods: A total of 188 participants were included in the analysis. The number of present teeth and functioning teeth were counted. Bacteria counts in tongue coat, oral wettability, tongue pressure, oral diadochokinesis (ODK), masticatory ability and bite force were examined. Swallowing function was assessed using the 10-item Eating Assessment Tool (EAT-10). Receiver operating characteristic curves were used to determine the cut-off points of each oral function parameter. A logistic regression model was performed to determine the combination of parameters with the highest accuracy for differentiating decline in swallowing function from normal. Results: Subjects with ODK /pa/ sound < 6.2 times/second had higher prevalence of swallowing problems than those with 6.2 times/second or more. EAT-10 scores of one or more were significantly related to older age (≥ 71 years old; odds ratio [OR] 4.321) and reduced ODK /pa/ sound (< 6.2 times/second; OR 2.914). Conclusions: Among community-dwelling elderly Japanese, those who were suspected of having decline in swallowing function had lower oral function than those who did not, and the cut-off values were 71 years of age and ODK /pa/ sound 6.2 times/s.