Association between Kidney Function and Comprehensive Frailty in Elderly Japanese Community-Dwelling Adults

Background: The Japanese government has implemented a new screening program to prevent the worsening of comprehensive frailty in older adults, and a new frailty assessment questionnaire for medical check-ups of old-old adults aged ≥75 years (QMCOO) has been developed starting in 2020. Few detailed studies have investigated renal function as a risk factor for comprehensive frailty. Therefore, this study examined the association between renal function and comprehensive frailty using the QMCOO score in Japanese community-dwelling elderly. Methods: Between April 2020 and March 2021, 4621 participants (mean age: 80.1 years; 39.5% male) underwent annual health check-ups in Nobeoka City, Miyazaki Prefecture, Japan. Subjects were divided into four groups based on their estimated glomerular filtration rate (eGFR): G4+5 (<30 mL/min/1.73m2, n=106), G3b (30–44 mL/min/1.73m2, n=473), G3a (45-59 mL/min/1.73m2, n=1477), and G1+2 (≥60 mL/min/1.73m2, n=2526). Associations between the eGFR groups and comprehensive frailty assessed using a cutoff score of 3/4 for the QMCOO (Geriatr Gerontol Int. 2023, 23,437) were examined. Physical, oral, nutritional, cognitive, and social frailty subdomains were also investigated. In a longitudinal analysis, the G1+2 group served as a reference to investigate the incidence of comprehensive frailty during the following year among participants without frailty at baseline (n=2398) using logistic regression models to examine odds ratios adjusted for potential confounders. Results: In this cross-sectional study, the frequency of comprehensive frailty increased with worsening renal function (G1+2: 21.5%; G3a: 23.2%; G3b: 32.8%, G4+5: 38.7%). The results were similar for the physical, oral, nutritional, and cognitive subdomains though no association between renal function and social frailty was identified. In the longitudinal study, a G4+5 eGFR was significantly associated with new-onset comprehensive frailty (G3a: odds ratio (OR): 0.83, 95% confidence interval (CI): 0.62–1.10; G3b: OR: 0.69, 95% CI: 0.43–1.09; G4+5: OR: 2.37, 95% CI: 1.10-5.20). Conclusion: A decline in renal function in older adults may be a risk factor for comprehensive frailty.