Oral Frailty and Its Association with Cognitive Function and Muscle Strength in Patients on Maintenance Hemodialysis: A Retrospective Observational Study

Background: Oral frailty is a new concept, introduced in Japan in 2013. In our preliminary study, oral hypofunction was observed in more than half of patients undergoing maintenance hemodialysis (MHD). This allowed us to determine the exact prevalence of oral frailty in MHD patients and investigate the association between oral cavity function, findings obtained via comprehensive geriatric assessment, and motor features. Methods: We initiated a two-week hospitalization program for MHD patients to evaluate frailty including oral cavity functions. Along with a comprehensive geriatric assessment and evaluation of motor functions, seven items pertaining to oral cavity functions were assessed by a professional dentist to determine oral frailty. After the incidence of each item had been determined, the association between these factors was retrospectively analyzed to explore the factors that affect oral frailty. Results: Oral frailty was observed in 33 out of 50 patients (66%). In particular, tongue lip motor functions were frequently impaired in this population. Oral cavity function scores, which increased as oral function deteriorated, negatively correlated with cognitive function (r = −0.349; p = 0.0129; 1−β = 0.71) and grip strength (r = −0.364; p = 0.00933; 1−β = 0.75). Conclusions: Oral frailty was commonly observed in MHD patients. We are currently considering implementing exercise programs to improve tongue lip motor function, enhance cognitive function through interprofessional cooperation, and strengthen grip.