Interrelationship between Oral Health, Nutrition, and Frailty in Older Adults: A Basis for Moderating Mediation Model

Oral health and malnutrition are significant modifiable factors contributing to frailty in older adults. However, the intrinsic pathways through which they are associated with frailty, as well as the moderating mechanisms involving psychosocial factors, remain unclear. This study aims to explore the mediating role of nutritional status in the relationship between oral health and frailty among community-dwelling older adults from the Wenhui, Wenhe, and Shuangqiao Subdistricts and to examine the moderating effect of social isolation on the "nutrition-frailty" pathway.

Employing a cross-sectional design, 409 community-dwelling older adults were recruited through convenience sampling in Yangzhou, China, from October 2022 to March 2023. Data collection involved a structured questionnaire that included the general information questionnaire, Tilburg Frailty Indicator, Oral Health Assessment Tool, Mini Nutritional Assessment Short Form, and Lubben Social Network Scale-6. Mediation and moderation analyses were conducted using PROCESS 3.4.1.

Nutritional status partially mediated the relationship between oral health status and frailty, with a mediation effect coefficient of 0.087 (95% CI: 0.051, 0.126) and a relative mediation effect of 16.54%. Social isolation significantly moderated the 'nutrition → frailty' pathway (interaction term β=0.20, P <0.01), with a moderation threshold of 4.875.

Oral health status is associated with frailty via nutritional status, while social isolation moderates the association between nutritional status and frailty.