Association between dry mouth and physical frailty among community-dwelling older adults in Japan: The Otassha Study

Objective To elucidate the relationship between physical frailty and dry mouth among community-dwelling older adults in Japan. Background Oral hypofunction is associated with physical frailty in older adults. Dry mouth, subjectively evaluated as xerostomia and objectively measured as hyposalivation, is highly prevalent in older adults. However, few reports have used both measures of dry mouth and investigated their association with physical frailty. Materials and Methods This cross-sectional study included 643 individuals (mean age, 73.9 years) from the Otassha Study in 2019. Xerostomia was assessed using the 5-item Summated Xerostomia Inventory (SXI). Hyposalivation was assessed by measuring the amount of resting saliva using the modified cotton roll method. Frailty phenotypes were defined by weakness, slowness, weight loss, low physical activity level and exhaustion components, and served as the outcome variable. Participants with three or more components were considered physically frail, and those with one or two components were considered pre-frail. Ordinal logistic regression analyses were performed to evaluate the associations between physical frailty and xerostomia and hyposalivation. Results Among the participants, 4.5% and 49.8% had physical frailty and pre-frailty, respectively. In ordinal logistic regression analysis adjusted for demographic and health characteristics, the SXI score was associated with physical frailty status (adjusted odds ratio for a one-point increase in SXI, 1.12; 95% confidence interval, 1.06-1.19). However, no difference was observed between the amount of resting saliva and severity of physical frailty. Conclusion Xerostomia is associated with physical frailty among community-dwelling older adults in Japan. Clinical Trial Registration: Not applicable.