Association between psychological frailty index and incident complete tooth loss among middle-aged and older adults: a prospective study based on CHARLS

Complete tooth loss is a severe oral health condition in middle-aged and older adults and is associated with impaired mastication, nutritional problems, reduced quality of life, and adverse ageing-related outcomes. Psychological frailty reflects multidimensional psychological vulnerability, but longitudinal evidence linking this construct to subsequent complete tooth loss remains limited. This study examined the prospective association between baseline psychological frailty index (PFI) and incident complete tooth loss using data from the China Health and Retirement Longitudinal Study (CHARLS). This longitudinal cohort analysis used the 2015 and 2018 waves of CHARLS. A total of 9,999 participants aged 45 years or older were included after excluding participants with missing PFI data, missing tooth-loss data, complete tooth loss at baseline, age younger than 45 years, or missing covariates. Baseline PFI was analyzed as a continuous 0–1 index and by quartiles. For continuous analyses, PFI was multiplied by 10; therefore, reported ORs represent each 0.1-unit increase in the original PFI score. Incident complete tooth loss was assessed at follow-up in 2018. Logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Restricted cubic spline models assessed the dose-response pattern. During follow-up, 603 participants developed incident complete tooth loss. Participants with incident complete tooth loss had a higher baseline PFI than those without this outcome. In the fully adjusted model, each 0.1-unit increase in PFI was associated with higher odds of incident complete tooth loss (OR = 1.090, 95% CI: 1.036 to 1.147, P < 0.001). When PFI was analyzed by quartiles, participants in the highest quartile had higher odds of incident complete tooth loss than those in the lowest quartile (OR = 1.314, 95% CI: 1.023 to 1.687, P = 0.032; P for trend = 0.015). Restricted cubic spline analyses indicated an approximately linear positive association, with no evidence of nonlinearity. Higher baseline PFI was associated with increased odds of incident complete tooth loss among middle-aged and older Chinese adults. These findings suggest that psychological frailty may be an underrecognized marker of oral health decline in ageing populations.