This cross-sectional study used a convenience sampling approach to recruit participants from two tertiary general hospitals in Chengdu, Sichuan Province, from November 2024 to March 2025. The inclusion criteria were as follows: ① age ≥18 years; ② confirmed CKD diagnosis according to established clinical criteria, encompassing stages 1–5 (17); ③ intact cognitive function with normal intellectual capacity and unimpaired verbal communication skills and capable of completing the questionnaire independently or with researcher assistance; and ④ provision of informed consent for voluntary participation in this study. The exclusion criteria were as follows: ① a history of severe mental illness or significant cognitive impairment; inability to complete the questionnaire; and ② severe cardiac, cerebral, or hepatic dysfunction or acute exacerbation of critical illness.

Before the questionnaires were distributed, all the investigators underwent systematic training covering scale interpretation, item specifications, response options, and scoring criteria. To ensure data completeness and objectivity, trained investigators provided face-to-face guidance via uniform instructions during questionnaire completion. The participants were expected to complete the questionnaires independently following the investigators’ explanations. However, for patients with extremely low educational levels or visual impairments who found it difficult to complete the questionnaire, investigators used neutral and nonsuggestive question-and-answer formats. The research team screened electronic medical records daily to identify eligible CKD patients on the basis of the inclusion criteria. After patients’ basic information was obtained, they communicated with them to assess their willingness to participate. After basic demographic information was obtained, the investigators assessed participants’ willingness to enroll in the study. Following the informed consent procedures, the participants spent an average of 20–30 min completing the questionnaire.

This study was approved by the Ethics Committee of the Affiliated Hospital of Chengdu University of Traditional Chinese Medicine. The ethical approval number of the study is 2024KL-047-01. This survey was in line with the principles outlined in the latest version of the Declaration of Helsinki. All participants voluntarily participated in this study and signed a paper informed consent form at the beginning of the study. All questionnaires in this study were filled out anonymously, ensuring that all data will only be used for data analysis in this study. Data may not be deposited in public repositories without the permission of participants.

All the statistical analyses were performed via SPSS software (version 26.0). Continuous variables with a normal distribution are presented as the means ± standard deviations and were compared via independent samples t tests for intergroup differences. Non-normally distributed continuous variables are presented as median (25th, 75th percentile). Comparisons between groups were performed via the Mann–Whitney U test. For categorical or ordinal variables, statistical descriptions are expressed as frequencies and percentages, whereas comparisons between groups were performed via the chi-square test. Variables with statistical significance in the univariate analysis were incorporated into binary logistic regression to identify independent influencing factors for oral frailty in middle-aged and older hospitalized CKD patients. A two-tailed p value < 0.05 was considered statistically significant.

A total of 311 questionnaires were distributed, with 307 valid questionnaires returned, yielding a high response rate of 98.7%. A total of 190 (61.9%) patients were in the oral frailty group, and 117 (38.1%) were in the nonoral frailty group. Among all CKD patients, 85 were aged younger than 60 years, and 222 were aged 60 years or older, with an average age of 67.50 ± 10.22 years. The sex distribution included 184 male patients and 123 female patients. The complete demographic characteristics are shown in Table 1.

The results of the univariate analysis revealed statistically significant differences (p < 0.05) between the oral frailty group and the nonoral frailty group in the following variables: age, marital status, educational level, self-care ability, dentures, dry mouth, comorbidities, MNA-SF score, RPFS-CV score, Hospital Depression Scale score, upper limb grip strength, hemoglobin, albumin, and serum calcium. However, there were no statistically significant differences (p > 0.05) between the two groups regarding sex, family monthly income, residential area, smoking history, drinking history, CKD stage, disease duration, BMI, Hospital Anxiety Scale score, triceps skin fold (TSF), calf circumference, serum phosphorus, creatinine, blood urea nitrogen, or GFR. The results are shown in Table 2.

The results of the multivariate logistic regression analysis revealed the independent influencing factors for oral frailty in middle-aged and older hospitalized CKD patients: marital status (OR = 3.508, 95%CI 1.296–9.493, p = 0.013), educational level at middle school or below (OR = 4.099, 95%CI 1.603–10.479, p = 0.003) and high school or above (OR = 3.122, 95%CI 1.105–8.823, p = 0.032), self-care ability (OR = 12.472, 95%CI 1.367–113.782, p = 0.025), dentures (OR = 12.098, 95%CI 5.787–25.293, p < 0.001), dry mouth (OR = 2.740, 95%CI 1.471–5.103, p = 0.001), and RPFS-CV scores (OR = 1.778, 95%CI 1.226–2.576, p = 0.002). The complete analysis results are shown in Table 3.

The results of this study revealed that the prevalence of oral frailty among middle-aged and older CKD patients reached 61.9%, which was significantly higher than the 48.7% reported in prior studies on the prevalence of oral frailty among middle-aged and older hospitalized patients in China (32) and higher than the 30.2 and 28.1% prevalence reported in community-dwelling older adults in China (33) and Japan (34). Several factors may contribute to this elevated prevalence. First, CKD patients often lack adequate knowledge about oral health, and there is a shortage or low utilization of regional oral healthcare resources in China, leading to unresolved oral health issues and progressive deterioration of oral hygiene (35). Second, the long-term burden of chronic diseases and adverse effects associated with dialysis lead to complications such as uremic toxin accumulation, impaired nutrient absorption, diminished oral tissue repair capacity, and increased susceptibility to infections (36), while also predisposing patients to a series of oral diseases, including dental calculus, gingivitis, and dental caries (37). All of these factors impose a significant oral health burden. These findings underscore the necessity for healthcare professionals to prioritize oral health education and promotion, conduct regular oral health assessments, and establish follow-up protocols for hospitalized CKD patients to prevent the onset and progression of oral frailty.

This study indicated that marital status was a significant factor influencing the development of oral frailty in CKD patients. Maintaining a marital relationship not only fosters the adoption of optimal oral hygiene practices but also contributes to the preservation of a positive psychological state in chronic disease patients, thereby increasing their ability to cope with long-term health challenges. Individuals in stable and fulfilling marriages typically benefit from reliable spousal support, which facilitates mutual health behavior monitoring, consequently reducing the risk of oral frailty (38). Additionally, a Japanese study revealed that single or divorced individuals who frequently dined alone presented irregular meal schedules, faster eating speeds, and inadequate chewing, resulting in insufficient exercise of oral functions and an increased risk of oral frailty (39). Therefore, when developing interventional strategies and public health policies concerning oral frailty for CKD patients, it is essential to consider the multifaceted impact of marital status.

This study also revealed that patients with lower educational levels (those with less than a bachelor’s degree) had a greater risk of oral frailty, which is consistent with the findings of Tu et al. (40). Individuals with limited education typically demonstrate reduced awareness of oral health maintenance, frequently engaging in suboptimal oral hygiene practices such as omitting bedtime brushing, insufficient brushing duration, employing horizontal scrubbing techniques, and maintaining a dietary preference for high-sugar soft foods. This population demonstrates minimal proactive engagement in acquiring knowledge regarding oral health management and disease prevention. Furthermore, they tend to misattribute oral frailty as an inevitable consequence of normal aging processes. This misconception ultimately leads to irreversible deterioration of chewing function and swallowing ability in CKD patients, thereby accelerating the progression of oral frailty (41). These findings underscore the imperative for healthcare professionals to prioritize oral frailty screening among CKD patients with limited education. Individualized oral health education programs and functional exercise schemes tailored to varying educational backgrounds are necessary.

The results of this study revealed that impaired self-care ability was an associated factor for oral frailty in CKD patients. When end-stage CKD patients experience a complete loss of self-care ability, they face difficulties in independently completing routine oral cleaning procedures. This functional limitation leads to the accumulation of food debris and bacteria in the oral cavity, thereby increasing the risk of oral infections, dental caries, and other oral health issues (42). Additionally, CKD patients with poor self-care ability have reduced physical activity, unbalanced nutritional intake, and impaired immune function, which further exacerbates oral frailty (43). Therefore, dynamically assessing the self-care ability of CKD patients and assisting family members in helping patients engage in appropriate physical exercise and oral function training can prevent oral issues from progressing to oral frailty.

The RPFS-CV score was significantly correlated with oral frailty in CKD patients. Research by Chen et al. indicated that fatigue results from multifactorial interactions, and its association with oral frailty may stem from shared pathophysiological mechanisms. Specifically, the systemic inflammatory response and metabolic disturbances resulting from uremic toxin accumulation following renal function deterioration in CKD patients invariably contribute to both fatigue and oral functional decline (44). This suggests that a multidisciplinary team could be established in clinical practice to achieve a balance between protecting renal function and promoting oral health while strengthening physical exercise and nutritional support for hospitalized CKD patients, thereby significantly improving their fatigue status and oral frailty (45).

Denture use has been identified as a significant influencing factor for oral frailty in CKD patients, which is consistent with the findings reported by Li et al. in 363 cancer patients undergoing chemotherapy (46). In CKD patients, disturbances in calcium–phosphorus metabolism and impaired nutritional absorption frequently contribute to alveolar bone resorption and gingival atrophy, which subsequently impair both swallowing coordination and chewing ability. Additionally, reduced saliva secretion not only increases the risk of denture dislodgement but also diminishes the natural cleansing capacity of the oral cavity. This dual effect predisposes patients to fungal colonization and the development of denture stomatitis, thereby increasing susceptibility to oral frailty (47). Consequently, healthcare professionals should first assist CKD patients in maintaining optimal natural dentition and provide specialized denture care guidance for patients wearing dentures. Second, they are encouraged to take regular follow-up examinations of their dentures and oral condition and utilize digital platforms to facilitate follow-up and remote consultation services (48).

This study revealed that dry mouth was significantly associated with oral frailty in CKD patients. In healthy individuals, saliva plays an immune defensive role against oral microorganisms by inhibiting fungal adhesion to epithelial cells (49). However, in CKD patients, impaired renal function adversely affects salivary gland physiology, directly leading to disruption of the oral immune barrier and ultimately resulting in adverse health outcomes such as oral frailty (6, 50). Oral frailty is a reversible condition. For CKD patients with dry mouth, a reasonable drinking and eating plan should be arranged to prevent the proliferation of oral bacteria due to dry mouth symptoms and delay the progression of oral frailty.

Moreover, future studies should examine the close association between CKD stage and oral frailty. Researchers should also further explore the impact of comorbidities in CKD patients, particularly diabetes, as independent variables on oral frailty to compensate for the shortcomings of this study. This will provide healthcare professionals with more professionally targeted prevention measures and standardized nursing strategies.