Effect of tongue strength on clinical outcomes of patients: A systematic review
Ayano Nagano, Junko Ueshima, Keita Tsutsumiuchi, Tatsuro Inoue, Akio Shimizu, Naoharu Mori, Keisuke Maeda
Abstract
OBJECTIVES: Whether decreased tongue strength is associated with poor clinical outcomes is unclear. This systematic review investigated the effect of decreased tongue strength on the clinical outcomes of adults requiring medical treatment. DESIGN: Systematic review. SETTING AND PARTICIPANTS: Systematic reviews, randomized control trials, intervention studies, and longitudinal observational studies involving patients with decreased tongue strength requiring medical treatment were included. METHODS: Articles published between January 2000 and June 2021 were retrieved from MEDLINE, CINAHL, Ichushi-web (in Japanese), Web of Science, ClinicalTrials.gov, UMIN, the Cochrane Library, and Cochrane Central Register of Controlled Trials. Risk of bias was assessed using the Risk of Bias Assessment Tool for Nonrandomized Studies. The study protocol was pre-registered in XXX. RESULTS: After screening 3040 articles and excluding duplicates, 74 articles were retrieved; after full-text evaluation of the 74 articles, seven articles (with 787 patients) were found to meet the inclusion criteria. The cut-off values for determining decreased tongue strength ranged from 13.8 to 21.6 kPa. Patients with decreased tongue strength had poorer recovery of their swallowing function, higher incidence of pneumonia, and poorer life expectancy than those with high tongue strength. However, tongue strength in older patients with decreased tongue strength increased when they performed physical exercise interventions and followed strict nutritional management plans. CONCLUSIONS: Decreased tongue strength was related to poor clinical outcomes in in- and outpatients. Oral frailty in older patients should be given increased attention in hospitals, and further research is needed to improve the clinical outcomes for older people with reduced tongue strength.