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BMC Oral Health
BMC Oral Health
BMC Oral Health
1472-6831
BioMed Central London

39272094
4872
10.1186/s12903-024-04872-9
Research
The current status and influencing factors of oral frailty in elderly maintenance hemodialysis patients based on the Andersen Oral Health Outcome Model
Chen Meiqian 12
He Mingqian 1
Gu Qingxin 1
Gao Xinru 1
Lu Guanzhen luguanzhen66@163.com

12
1 grid.413679.e 0000 0004 0517 0981 Department of Scientific Research, Huzhou Central Hospital, Affiliated Central Hospital Huzhou University, Zhejiang, China
2 https://ror.org/04mvpxy20 grid.411440.4 0000 0001 0238 8414 School of Medicine and Nursing, Huzhou University, Zhejiang, China
13 9 2024
13 9 2024
2024
24 10858 7 2024
5 9 2024
© The Author(s) 2024
2024
https://creativecommons.org/licenses/by-nc-nd/4.0/ Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.
Objectives

To analyse the elements that influence oral frailty in elderly maintenance hemodialysis patients and to comprehend the present state of this condition.

Methods

A survey of 325 elderly maintenance hemodialysis patients from three hospitals in Huzhou City was conducted using a general information questionnaire, the Oral Health Assessment Tool, the Knowledge, Attitude, and Practice of Oral Health Questionnaire, the Social Frailty, the Frail Scale, and the Oral Frailty Index.

Results

In elderly maintenance hemodialysis patients, the prevalence of oral frailty was 45.2%. Factors influencing it include the Oral Health Knowledge Score (OR = 0.84, 95% CI 0.72–0.98), Oral Health Behavior Score (OR = 0.95, 95% CI 0.92–0.98), insufficient dialysis (OR = 0.30, 95% CI 0.14–0.63), social frailty (OR = 3.72, 95% CI 1.57–8.83), physical frailty (OR = 3.12, 95% CI 1.55–6.30), number of missing teeth (OR = 1.09, 95% CI 1.03–1.15), swallowing abnormalities (OR = 2.84, 95% CI 1.26–6.38), and oral health scores (OR = 1.34, 95% CI 1.14–1.57) (P < 0.05).

Conclusion

Patients on elderly maintenance hemodialysis are more susceptible to oral frailty. Nursing staff should develop scientifically sound, effective, and targeted oral management strategies for these patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-024-04872-9.

Keywords

Maintenance hemodialysis
Elderly
Oral frailty
Risk factor
issue-copyright-statement© BioMed Central Ltd., part of Springer Nature 2024
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pmcIntroduction

The incidence of renal disease is rising annually in tandem with the rapidly aging population. Globally, there are 697.5 million chronic kidney disease (CKD) patients, accounting for 9.1% of the global population, and this amount is anticipated to keep rising in the coming decades [1]. With 132.3 million of them, China was the nation with the greatest number of CKD sufferers globally. The incidence of CKD in China’s elderly population over 60, 65, and 80 years old was 19.25%, 32–37%, and 59%, respectively, which was much higher than the incidence of 10.8% among the middle-aged population [1–3]. As the disease progresses, irreversible decline in kidney function occurs, leading to 2% cases eventually developing into end-stage renal disease (ESRD) [4]. Maintenance hemodialysis (MHD) is the primary renal replacement therapy for elderly ESRD patients.

The core characteristic of frailty is a multidimensional decline in physiological reserves, leading to adverse health outcomes such as falls, fractures, hospitalization, and mortality among patients with maintenance hemodialysis (MHD) [5, 6]. The prevalence of frailty in MHD patients is 46%, with advanced age increasing the risk of frailty [7]. While blood dialysis extends the life expectancy of MHD patients, the frailty symptoms related to oral health in elderly MHD patients have become a focal point of scholarly attention. The biochemical changes in the blood caused by ESRD and MHD have a major impact on the oral health of MHD patients [8–10]. Due to the combined effects of reduced saliva secretion, weakened immune systems, and various medications, most elderly MHD patients face poorer oral health conditions as they age, including issues such as reduced tooth count and periodontitis. This contributes to an increased risk of oral frailty [11]. Oral frailty refers to the gradual loss of oral and facial structures and functions associated with aging [12]. Compared to other countries, the prevalence of oral frailty among elderly people in China was relatively high (45.9%) [13]. Studies indicated that oral frailty potentially interacts with the body to malnutrition, inflammatory responses, and reduced quality of life, which may result in adverse health outcomes in elderly individuals, including increased risks of frailty, myocardial infarction, disability, and death [12]. However, there is currently limited research specifically investigating oral frailty in elderly MHD patients, highlighting the need for further research.

Current research on oral frailty in elderly people has predominantly employed quantitative methods to investigate influencing factors, without the support of theoretical models [14, 15]. These studies generally provided a relatively broad survey of the factors, leading to inconsistent conclusions. The Andersen Oral Health Outcomes Model was created by the International Collaborative Study on Oral Health Outcomes and is based on Andersen’s Behavioral Model of Health Services Use. This methodology takes a systematic approach to investigating the factors that influence oral health outcomes in detail [16]. This model links oral health outcomes to exogenous factors (age and race), primary determinants of oral health outcomes (dental care systems, environmental factors, and demographic characteristics), and oral health behaviors (dental service utilization and personal habits). Elderly MHD patients’ incidence of oral frailty is potentially influenced by primary drivers of oral health habits and oral health behaviors. Therefore, this study employs the Andersen Oral Health Outcomes Model and hypothesizes that the incidence of oral frailty in elderly MHD patients is significantly influenced by key determinants of oral health outcomes and oral health behaviors (Fig. 1). This research aimed to provide references for healthcare professionals in dialysis units to implement more scientific, effective and targeted oral management strategies.

Fig. 1 Theoretical model. Green box: Exogenous factors; Yellow box: Oral health behaviors; Blue box: Primary determinants of oral health outcomes; Gray box: Oral health outcomes; Bold font: Andersen Oral Health Outcomes Modeld framework; Brackets: Variables

Method

Study participants

From January to June 2024, a cluster sampling method was used to include elderly MHD patients from Huzhou Central Hospital, Huzhou People’s Hospital, and Huzhou Traditional Chinese Medicine Hospital as the study subjects. Inclusion criteria were as follows: (1) Undergoing hemodialysis treatment for 3 months or more; (2) Aged 60 years or older; (3) Clear consciousness with normal hearing and speaking abilities; (4) committed with informed involvement in the research. Exclusion: (1) Peritoneal dialysis or kidney transplant recipients; (2) Patients with cognitive impairment, communication barriers, or psychiatric disorders; (3) Those who had experienced severe complications within the past month, such as acute heart failure or malignant tumours. Written and verbal explanations regarding the research were provided to all participants, along with written informed consent forms. A questionnaire was distributed to 330 patients who met the inclusion and exclusion criteria. After collection, it was found that 5 questionnaires had more than 50% missing data. Consequently, the complete data from the remaining 325 patients were analyzed.

Measures

Oral frailty index-8

Oral frailty was the dependent variable in the study. There are eight items on the Oral Frailty Index-8 (OFI-8) [17]. Responses to the following items were scored: difficulties eating hard foods compared to six months ago, recent choking while eating, and wearing dentures. A response of “Yes” was scored as 2 points, while “No” was scored as 0 points. The following items were scored: inability to eat hard foods, feeling dry mouth, reduced frequency of outings compared to one year ago, brushing teeth fewer than twice a day and visiting the dentist less than once a year. A response of “Yes” was scored as 1 point, while “No” was scored as 0 points. The total score ranged from 0 to 11. A score of four or above is indicative of oral fragility. The survey employed a Chinese questionnaire that had been cross-culturally adapted. This questionnaire was previously validated in the Chinese population, with a Cronbach’s alpha coefficient of 0.949, indicating excellent internal consistency [18].

Social frailty index

Teo et al. developed the Social Frailty Index (SFI) [19]. The scale consists of seven items, each worth one point for a “Yes” response and zero for a “No” response. The total score ranged from 0 to 7. A total score between 2 and 7 indicates social frailty. The cross-culturally adapted Chinese questionnaire was validated in the Chinese population with a Cronbach’s alpha coefficient of 0.82, demonstrating good internal consistency [20].

The frail scale

The Frail Scale (FRAIL) consists of 5 items: fatigue, resistance (strength), ambulation (mobility), illnesses (number of comorbidities), and weight loss [21]. The one point for a “Yes” response and zero for a “No” response. The FRAIL scale has a total score that goes from 0 to 5, where a value of ≥ 3 denotes frailty. For this survey, the cross-culturally adapted Chinese questionnaire was used, and it had a Cronbach’s alpha coefficient of 0.826 in prior validation with the Chinese population, indicating good internal consistency [22].

Oral health assessment tool

The lips, tongue, gum tissue, saliva, natural teeth, dentures, oral hygiene, and dental pain are among the eight components that make up the Oral Health Assessment Tool (OHAT). The scores for each item are 0 (normal), 1 (abnormal), or 2 (severely aberrant). A higher total score indicates poorer oral health. After cross-cultural adaptation, the Cronbach’s alpha coefficient was 0.71 [23].

The knowledge, attitude, and practice of oral health questionnaire

The Chinese questionnaire was developed by Ye et al. [24]. It consists of three sub-questionnaires, including knowledge, beliefs, and behavior, the Cronbach’s alpha coefficient was 0.77, 0.81 and 0.84, respectively. The four dimensions of the knowledge questionnaire—oral health affecting factors, unpleasant oral symptoms, oral hygiene procedures, and oral hygiene tools—each have 19 items; the beliefs questionnaire includes 4 dimensions with 17 items (benefits of oral health, severity of adverse oral conditions, susceptibility, and barriers); the behavior questionnaire includes 2 dimensions with 11 items (oral health maintenance practices and dental hygiene practices). Responses were scored as follows: “Agree” received 1 point, while “Disagree” or “Not Sure” received 0 points. Items 12–14 and 18 of the Oral Health Knowledge Scale, as well as items 4, and 13–17 of the Belief Scale, were reverse-scored. The total of the Oral Health Knowledge Scale scores ranged from 0 to 19. The total of the Oral Health Belief Scale score ranged from 0 to 17. The total of the Oral Health Behavior Scale scores ranged from 11 to 55. Higher scores on these sub-questionnaires indicate better oral health knowledge, attitudes, and practices.

Other variates

Based on the literature review and expert opinions, a general information questionnaire was designed, which includes demographic data, disease-related information, and biochemical indicators. Demographic data includes age, sex, pre-retirement occupation, smoking status, average monthly household income, and educational level. Disease-related information includes duration of dialysis, number of medications, number of diseases, number of missing teeth, and presence of swallowing abnormalities [25]. The number of diseases and medications was assessed through multiple-choice questions. Swallowing abnormalities were evaluated by the rapid, repeated swallowing of saliva within 30 s; ≥3 times indicated no swallowing abnormalities, otherwise considered present. Biochemical indicators include the serum albumin level, serum calcium level, and single pool clearance index (spKt/V). The bromocresol green method measured albumin levels. Levels below 35 g/L were considered low albumin. Serum calcium levels were measured by the arsenazo method. Levels below 2.25 mmol/L were considered low serum calcium. A spKt/V level ≥ 1.2 indicated adequate dialysis adequacy [26]. The spKt/V calculation is as follows: spKt/V = -In(R-0.008t) + (4-3.5R)×ΔBW/BW, where R is the post-dialysis urea nitrogen/pre-dialysis urea nitrogen ratio, t is the treatment time (h), ΔBW is the ultrafiltration volume (L), and BW is the post-dialysis body weight (kg).

Statistical analysis

Two individuals independently entered data using different computers in Epidata 3.1 software. Data consistency was checked post-entry to ensure the accuracy of the analysis data. The statistical analysis was carried out with SPSS 26.0. The Kolmogorov-Smirnov test was used to assess the normality distribution of the data. Results were shown as mean ± standard deviation for continuously distributed normally distributed variables, and the independent samples t test was used for analysis. The Mann-Whitney U test was used to analyse non-normally distributed variables, which were expressed as the median and interquartile range. For categorical data, descriptive statistics such as rates and proportions were employed, and the chi-square test was utilized for analysis. Subsequently, multicollinearity checks were performed for all variables. Variance inflation factors (VIF) for each variable were below 5, indicating no multicollinearity between the independent variables (Supplementary Table S1). The variable with a P value < 0.1 were selected as independent variables, with the occurrence of oral frailty as the dependent variable, for logistic regression analysis, adjusted for demographics. In logistic regression analysis, a P value < 0.05 was considered statistically significant.

Results

Among 325 elderly patients, males were slightly more prevalent (55.7%), with females accounting for 44.3%. 53.2% of the patients had only completed elementary school or less in terms of education. The majority of elderly patients had undergone treatment for over 5 years (45.5%), followed by those treated for 1 to 5 years (42.5%). Most elderly patients used five or more medications (58.8%). A significant proportion had swallowing abnormalities (69.5%), physical frailty (55.1%), and hypocalcemia (51.4%). Among the 325 elderly MHD patients, 45.2% exhibited oral frailty, while 54.7% did not (Table 1).

Table 1 Comparison and univariate analysis of the characteristics of oral frailty in elderly MHD patients (n = 325)

Covariates	N	Oral frailty	Statistics	P	
Yes(n = 147)	No(n = 178)	
Age, n(%)				18.056a	<0.001	
60～70	148	48(32.7)	100(56.2)			
70～80	138	78(53.1)	60(33.7)			
> 80	39	21(14.3)	18(10.1)			
Gender, n(%)				0.414a	0.52	
Male	181	79(53.7)	102(57.3)			
Female	144	68(46.3)	76(42.7)			
Smoking, n(%)				-0.101a	0.751	
Yes	66	31(21.1)	35(19.7)			
No	259	116(78.9)	143(80.3)			
Pre-retirement occupation, n(%)				20.134a	<0.001	
Intellectual	50	15(10.2)	35(19.7)			
Worker	132	62(42.2)	70(39.3)			
Farmer	104	61(41.5)	43(24.2)			
Other	39	9(6.1)	30(16.9)			
Average monthly household income, n(%)				9.582a	0.022	
Below 1000 RMB	54	32(21.8)	22(12.4)			
1000～3000 RMB	101	51(34.7)	50(28.1)			
3000～5000 RMB	81	32(21.8)	49(27.5)			
Over 5000 RMB	89	32(21.8)	57(32.0)			
Education level, n(%)				29.616a	<0.001	
Primary school and below	173	102(69.4)	71(39.9)			
Middle school	94	29(19.7)	65(36.5)			
High school or vocational school	44	14(9.5)	30(16.9)			
College degree or above	14	2(1.4)	12(6.7)			
Duration of dialysis, n(%)				0.300a	0.861	
3 months～1 year	39	18(12.2)	21(11.8)			
1～5 years	138	60(40.8)	78(43.8)			
Over 5 years	148	69(46.9)	79(44.4)			
Number of medications, n(%)				2.968a	0.085	
≥ 5	191	94(63.9)	97(54.5)			
<5	134	53(36.1)	81(45.5)			
Number of diseases, n(%)				3.719a	0.054	
≥ 5	127	49(33.3)	78(43.8)			
<5	198	98(66.7)	100(56.2)			
Number of missing teeth, M(Q1,Q3)	1(0, 6)	3(0, 11)	0(0, 3)	-4.640b	<0.001	
Swallowing abnormalities, n(%)				40.643a	<0.001	
Yes	226	76(51.7)	150(84.3)			
No	98	70(47.6)	28(15.7)			
Serum albumin level, n(%)				0.419a	0.517	
<35 g/L	85	41(27.9)	44(24.7)			
≥ 35 g/L	240	106(72.1)	134(75.3)			
Serum calcium level, n(%)				0.117a	0.732	
<2.25mmol/L	167	74(50.3)	93(52.2)			
≥ 2.25mmol/L	158	73(49.7)	85(47.8)			
Dialysis adequacy, n(%)				31.449a	<0.001	
<1.2	103	70(47.6)	33(18.5)			
≥ 1.2	222	77(52.4)	145(81.5)			
OHAT, M(Q1,Q3)	6(5, 8)	8(6, 10)	5(4, 7)	-7.931b	<0.001	
SFI				51.365a	<0.001	
Yes	93	13(8.8)	80(44.9)			
No	232	134(91.2)	98(55.1)			
FRAIL, M(Q1, Q3)				42.111a	<0.001	
Yes	179	52(35.4)	127(71.3)			
No	146	95(64.6)	51(28.7)			
Oral Health Knowledge Score, M(Q1, Q3)	9(7, 11)	8(5, 10)	10(8, 12)	-6.897b	<0.001	
Oral Health Belief Score, M(Q1, Q3)	10(7, 13)	8(5, 12)	12(9, 14)	-5.923b	<0.001	
Oral Health Behavior Score, M(Q1, Q3)	18(4, 32)	7(4, 24)	26(5, 37)	-4.497b	<0.001	
a Mann-Whitney test

bChi-square test

M: Median, Q₁: 1st Quartile, Q₃: 3st Quartile; OHAT: Oral Health Assessment Tool; SFI: Social Frailty Index; FRAIL: The Frail Scale; RMB: Renminbi (Chinese currency name). P: P value. N or n: sample size

The study employed binary logistic regression analysis, where the dependent variable was the occurrence of oral frailty in elderly MHD patients, and the independent variables were number of medications, number of diseases, swallowing abnormalities, dialysis adequacy, SFI, FRAIL, number of missing teeth, OHAT, oral health knowledge score, oral health belief score and oral health behavior score. Table 2 presented the final results, in Model 1, swallowing abnormalities, dialysis adequacy, SFI, FRAIL, number of missing teeth, OHAT, oral health knowledge score, oral health belief score, and oral health behavior score significantly influenced the occurrence of oral frailty (P < 0.05). After adjusting for Model 2, swallowing abnormalities (OR = 2.84, 95% CI 1.26–6.38), insufficient dialysis (OR = 0.30, 95% CI 0.14–0.63), SFI (OR = 3.72, 95% CI 1.57–8.83), FRAIL (OR = 3.12, 95% CI 1.55–6.30), number of missing teeth (OR = 1.09, 95% CI 1.03–1.15), higher OHAT score (OR = 1.34, 95% CI 1.14–1.57), lower oral health knowledge score (OR = 0.84, 95% CI 0.72–0.98), and oral health behavior score (OR = 0.95, 95% CI 0.92–0.98) increased the likelihood of oral frailty in elderly MHD patients (P < 0.05).

Table 2 Logistic regression analysis of oral frailty of the elderly elderly MHD patients

	Model1a	P	Model2b	P	
Variables	OR (95%CI)	OR (95%CI)	
Number of medications					
< 5	1.00 (Reference)		1.00 (Reference)		
≥ 5	1.48 (0.95 ~ 2.32)	0.086	0.62 (0.30 ~ 1.27)	0.193	
Number of diseases					
< 5	1.00 (Reference)		1.00 (Reference)		
≥ 5	1.56 (0.99 ~ 2.45)	0.054	0.89 (0.44 ~ 1.83)	0.757	
Swallowing abnormalities					
No	1.00 (Reference)		1.00 (Reference)		
Yes	5.00 (2.98 ~ 8.39)	< 0.001	2.84 (1.26 ~ 6.38)	0.012	
Dialysis adequacy					
No	1.00 (Reference)		1.00 (Reference)		
Yes	0.25 (0.15 ~ 0.41)	< 0.001	0.30 (0.14 ~ 0.63)	0.002	
SFI					
No	1.00 (Reference)		1.00 (Reference)		
Yes	8.41 (4.43 ~ 15.98)	< 0.001	3.72 (1.57 ~ 8.83)	0.003	
FRAIL					
No	1.00 (Reference)		1.00 (Reference)		
Yes	4.55 (2.85 ~ 7.27)	< 0.001	3.12 (1.55 ~ 6.30)	0.001	
Number of missing teeth	1.14 (1.09 ~ 1.19)	< 0.001	1.09 (1.03 ~ 1.15)	0.003	
OHAT	1.48 (1.33 ~ 1.65)	< 0.001	1.34 (1.14 ~ 1.57)	< 0.001	
Oral Health Knowledge Score	0.77 (0.71 ~ 0.83)	< 0.001	0.84 (0.72 ~ 0.98)	0.024	
Oral Health Belief Score	0.82 (0.77 ~ 0.88)	< 0.001	0.96 (0.84 ~ 1.09)	0.526	
Oral Health Behavior Score	0.97 (0.95 ~ 0.98)	< 0.001	0.95 (0.92 ~ 0.98)	< 0.001	
aModel 1: Crude

bModel 2: Adjusted: age, pre-retirement occupation, average monthly household income, and educational level

Discussion

Among elderly MHD patients who have undergone treatment for three months or more, their physical condition tends to stabilize, making the survey results more representative. Oral frailty was found in 45.2% of elderly MHD patients in our study, higher than that of community-dwelling elderly individuals (23.1%) and elderly hospitalized patients (31.0%) [13]. Possible reasons for this difference include the following: First, half of the MHD patients experienced xerostomia [8]. Due to hemodialysis treatment, fluid intake restrictions, and side effects of medications, the salivary flow rate decreases, allowing microorganisms to accumulate and adhere more effectively in the oral environment. This results in subjective dry mouth and raises the possibility of oral fragility by decreasing the preventive effects of saliva on teeth and oral mucosa [27]. According to studies, MHD patients with xerostomia can alleviate thirst by chewing gum, oral moisturizing gels, and low-temperature stimulation of oropharyngeal receptors [28]. Facial muscle and tongue exercises were also effective interventions to increase salivary flow [29]. Then,, MHD patients generally had poor oral health compared to healthy controls [30]. They tend to have worse gingival and periodontal conditions. Regular daytime treatment schedules might prevent MHD patients from visiting dentists. Healthcare providers in hemodialysis units should prioritize the oral health management of MHD patients. Forming multidisciplinary teams with dentists and psychologists can enhance oral health guidance and help patients develop good oral hygiene habits.

According to the study’s findings, higher scores in oral health knowledge and oral health behavior were protective factors against the occurrence of oral frailty. This finding is consistent with the Andersen Oral Health Outcomes Model’s prediction that improving health behaviors can mitigate adverse health outcomes. This may be due to patients’ incomplete understanding of the risk factors and preventive measures for oral diseases, which leads to them using oral hygiene services seldom and developing bad habits such as not rinsing their mouths after meals and brushing irregularly. Periodontal disorders, dental caries, and oral fragility were all influenced by these behaviors. This conclusion aligns with the findings of studies by Dou et al. [31]. Furthermore, cognitive decline in the elderly affects their understanding and memory of oral health knowledge, thereby impacting their adherence to recommended oral hygiene practices [32]. This decline also diminishes self-care abilities, increasing the risk of oral frailty. Reduced physical activity also limits opportunities for elderly individuals to engage in oral care, making it more challenging to perform daily oral hygiene tasks [33]. This neglect can exacerbate issues such as cavities and periodontal disease, which are associated with increased oral frailty. Research had shown that the more patients understand adverse health outcomes related to oral health, the more proactive they are in protecting their oral health [22]. Healthcare providers should actively educate patients on oral health care, encourage the adoption of good oral hygiene practices, correct avoidance behaviors, foster proactive attitudes, and enhance patients’ ability to care for their oral health.

The spKt/V is a crucial indicator for assessing dialysis adequacy in MHD patients. Insufficient spKt/V indicates poor dialysis adequacy, which may lead to the accumulation of toxins and metabolic waste in the body. This accumulation negatively impacts overall health, including oral health, by affecting nutritional status and muscle mass [34]. Inadequate dialysis also leads to disruptions in calcium and phosphorus metabolism, lowering blood calcium levels, which accelerates the frailty process in MHD patients [35]. Sufficient calcium is essential for protecting dental enamel and preventing tooth dissolution. Therefore, it can be inferred that inadequate dialysis disrupts periodontal support tissues, decreases the number of teeth, and increases the risk of developing oral frailty. However, in our study, the effects of albumin and calcium levels on oral frailty were not significant. This may be because their impact on oral frailty could be mediated through spKt/V, which requires further data for confirmation.

The study results suggest that social frailty, physical frailty, a higher number of missing teeth, a higher OHAT score, and swallowing abnormalities significantly increase the risk of oral frailty. These findings are consistent with the Andersen Oral Health Outcomes Model, which emphasizes the interaction between health conditions and frailty factors. This study indicated that social frailty in elderly MHD patients is a significant factor influencing oral frailty. Diminished self-esteem and less structured treatment significantly impacted patients’ social interactions. As social function declines, opportunities for conversation decrease, leading to reduced tongue pressure, weakened chewing, and slowed tongue movement [15], thereby causing oral frailty. Thus, preventive strategies for oral frailty should focus on improving patients’ social functioning, increasing opportunities for communication, and exercising oral muscles and functions. Consistent with findings from research by Tu et al., the results of this investigation showed that elderly MHD patients who are physically fragile are more prone to oral frailty [36]. Patients undergoing MHD treatment experience further declines in physical function, associated with sarcopenia and reduced physical activity, influencing one’s capacity for chewing and swallowing and raising the possibility of oral frailty [37]. MHD patients who lack exercise exhibit greater degrees of physical frailty compared to those who exercise regularly. It is recommended to patients supervise and with virtual reality exercises and other methods to improve their physical fitness and muscle strength, thereby preventing further deterioration [38].

Among elderly MHD patients, lower OHAT served as protective factors against oral frailty. The chance acquiring oral frailty higher in those with higher OHAT. Dental caries and periodontitis were two of the main reasons for tooth loss, and poor oral health conditions such as reduced saliva and oral pain are related to declining oral function [39]. According to this study, elderly MHD patients’s oral frailty may be influenced by their swallowing difficulties and the quantity of lost teeth. A reduced number of teeth leaded to misalignment of the bite and decreased chewing ability [40]. Swallowing disorders impaired swallowing ability, further exacerbating oral frailty [41]. Saliva secretion was stimulated, and swallowing function was improved by Strengthening of Oral and Swallowing Muscles (SOE) training, which consists of exercises for stretching the masticatory muscles and tongue, mouth-opening training, salivary gland massage, head and neck movements, and speaking exercises [42]. However, the impact of SOE training on chewing function was not significant because it is more effective for individuals with complete dentition than those with missing teeth. Compared to other causes of oral frailty, the reduction in the number of teeth was the most common factor. Therefore, patients with missing teeth should be encouraged to wear dentures and learn denture care methods to prevent the progression of oral frailty. Healthcare providers should encourage patients to undergo oral rehabilitation treatment combined with oral exercise training to maintain oral function in elderly MHD patients. Furthermore, the oral health metric most strongly correlated with death was the quantity of lost teeth. For every 10, 20, and 32 teeth lost, the relative risk of all-cause mortality increases by 15%, 33%, and 57%, respectively [43]. Thus, the number of missing teeth can be used as a specific indicator to assess the dental health of individuals.

This study has the following limitations. Firstly, the research sample was limited to elderly MHD patients from three Class-A tertiary hospitals in Huzhou City, thus resulting in a limited sample size and potential representativeness. This may impact the generalizability of the study results. The second limitation of this study was that it was cross-sectional, only able to observe data at a single time point and unable to establish causal relationships. Longitudinal observational studies are needed to elucidate how various influencing factors affect the prevalence of oral frailty in elderly MHD patients and to explore their underlying mechanisms.Thirdly, speech difficulties are a component of oral frailty. The inclusion criterion of normal speech ability was intended to ensure that participants did not have pre-existing speech disorders that could confound the assessment of oral frailty. However, no patients with speech difficulties conflicting with this criterion were encountered during the study. Future research should aim to better address this issue.

Conclusions

Among elderly MHD patients, oral frailty was comparatively prevalent. The main impacting factors included oral health knowledge scores, oral health behavior scores, dialysis adequacy, social frailty, physical frailty, the number of missing teeth, swallowing disorders, and OHAT. These findings suggested that healthcare providers should incorporate oral health education into their routine work. Early detection and treatment of oral frailty may serve as preventive measures to reduce medical and nursing costs and delay the onset and progression of oral frailty. Future studies should also involve multicenter longitudinal research to establish causal relationships between various factors and the prevalence of oral frailty in elderly MHD patients. This would help explore potential mechanisms and the long-term effects of interventions.

Electronic supplementary material

Below is the link to the electronic supplementary material.

Supplementary Material 1

Acknowledgements

We are grateful to the patients who are willing to participate in the study.

Author contributions

Meiqian Chen: Writing original draft, Software. Mingqian Chen: Methodology, Data curation. Qingxin Gu: Data collection. Xinru Gao: Data collection. Guanzhen Lu: Writing review & editing, Conceptualization.

Funding

None.

Data availability

The datasets generated and/or analysed during the current study are not publicly available due to involved patient privacy but are available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

Huzhou Normal University’s Medical Ethics Committee approved this study (Approval No. 202401-07). All participants agreed to participate in this study and signed an informed consent form.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.

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Meiqian Chen and Mingqian He equally contributed to this work.
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References

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