Comparative Analysis of the OF-5 and OFI-8 Tools in Assessing Oral Frailty and Their Association with Systemic Health Indicators

Introduction: Oral frailty, defined as an age-related decline in oral function, represents a significant risk factor for adverse health outcomes, though it can be mitigated through early intervention. The Oral Frailty Five-item Checklist (OF-5), introduced in 2023, assesses oral frailty using five indicators: reduced number of teeth, difficulty chewing, difficulty swallowing, dry mouth, and low articulatory oral motor skills. Designed for use beyond dental clinics, the OF-5 has demonstrated predictive validity for physical frailty and mortality. Similarly, the Oral Frailty Index-8 (OFI-8) comprises eight items evaluating oral health, social participation, and dental habits. Methods: This study compared the OF-5 and OFI-8 tools and investigated their associations with physical and biological markers. A cross-sectional analysis was conducted on 270 Japanese participants aged ≥ 65 years (mean age: 77.6 ± 7.3 years). The assessments included blood tests, physical measurements, and grip strength evaluation. Participants were categorized by sex and oral frailty risk based on OF-5 scores (non-frailty: ≤ 1; frailty: ≥ 2). Results: Oral frailty, defined as an OF-5 score ≥ 2, was observed in 40.7% of the participants (33.8% in men and 47.4% in women). Both the OF-5 and OFI-8 scores were higher in women than in men. Sex-specific differences in physical and biological markers were evident; men exhibited higher grip strength, whereas women had a higher prevalence of anemia and osteoporosis. Women were also more likely to report reduced masticatory ability and lower levels of social participation. A high concordance rate of over 80% was observed between oral frailty (OF-5 score ≥ 2) and high-risk oral frailty (OFI-8 score ≥ 4). Conclusions: These findings highlight the utility of subjective questionnaires in assessing oral frailty and emphasize the need for longitudinal studies to evaluate their predictive accuracy for physical frailty.