Association between oral frailty and cystatin C-related indices—A questionnaire (OFI-8) study in general internal medicine practice

BACKGROUND: Cystatin C-related indices such as the ratio of creatinine to cystatin C (Cr/CysC) and the ratio of estimated glomerular filtration rate by cystatin C (eGFRcys) to creatinine eGFRcre (eGFRcys/eGFRcre) levels have been shown to be associated with muscle mass and strength and can be markers of sarcopenia. Oral frailty is defined as an age-related gradual loss of oral functions, accompanied by a decline in cognitive and physical functions. It results in adverse health-related outcomes in older age, including mortality, physical frailty, functional disability, poor quality of life, and increased hospitalization and falls. Therefore, poor oral health among the elderly is an important health concern due to its association with the pathogenesis of systemic frailty, suggesting it to be a multidimensional geriatric syndrome. The Oral Frailty Index-8 (OFI-8) is a questionnaire that can be used for easy screening of oral frailty. This study aimed to investigate whether cystatin C- related indices are different between patients with low to moderate risk of oral frailty and those at high risk of oral frailty, using the OFI-8 in attending a general internal medicine outpatient clinic. MATERIALS AND METHODS: This is a cross-sectional study that included 251 patients with a mean age of 77.7±6.6 years and a median age of 77 years (128 men: mean age, 77.1±7.3 years; median age, 77 years and 123 women: mean age, 78.4±5.7 years; median age, 78 years) attending general internal medicine outpatient clinics. OFI-8 scores were tabulated by gender to determine whether there were differences between patients at low to moderate risk of oral frailty (OFI-8 score ≤3 points) and those at high risk (OFI-8 score ≥4 points) in Cr/CysC, eGFRcys/eGFRcre levels, height, weight, grip strength, etc. were examined. RESULTS: The OFI-8 score was higher in women than in men, suggesting that oral frailty is more common in women. Cr/CysC, eGFRcys/eGFRcre and grip strength were significantly lower in both men and women in the high-risk group for oral frailty (OFI-8 score ≥ 4). Height, hemoglobin level, red blood cell count, and serum albumin levels were significantly lower in men with an OFI-8 score ≥4. Receiver operating characteristic curve (ROC) analysis also showed that Cr/CysC and eGFRcys/eGFRcre were significantly associated with an OFI-8 score≥4 in both men and women. CONCLUSION: Cr/CysC and eGFRcys/eGFRcre were significantly lower in the high-risk group for oral frailty on the OFI-8in both men and women. A relationship exists among cystatin C-related indices, which can effectively screen systemic frailty. Similarly, the OFI-8 score can be used to effectively screen oral frailty. Thus, a collaboration that incorporates both systemic and oral frailty from medical and dental perspectives is required.