The relationship between oropharyngeal dysphagia and dehydration in older adults

Abstract

Background

Relationship between dysphagia and dehydration has not been studied widely. The aim of this study is to determine the frequency of dysphagia and dehydration in geriatric outpatient clinic, to evaluate the relationship between these two conditions.

Methods

The cross-sectional study included 1345 patients. Plasma osmolarity (Posm) was calculated using the following formula: [1.86 x (Na + K) + 1.15 x glucose + urea + 14]. Overt dehydration was defined as a calculated Posm of > 300 mmol/L. Eating Assessment Tool (EAT-10) score of ≥ 3 was accepted as dysphagia. Associations between dehydration and dysphagia was evaluated.

Results

Mean age was 78 ± 8 years, and 71% were females. Dysphagia was observed in 27% of patients. Dysphagia was associated with a higher number of drug exposure, dependency on basic activities of daily living and geriatric depression (p < 0.05). Overt dehydration was found in 29% of patients with dysphagia, and 21% of patients with no dysphagia (p = 0.002); and dysphagia was significantly associated with overt dehydration mmol/L (OR 1.49, 95% CI 1.13–1.96, p = 0.005) after adjustments for age and sex. In another model, EAT-10 score was found as one of the independent predictors of overt dehydration (OR1.03, 95% CI 1.00-1.06, p = 0.38), along with diabetes mellitus (OR 2.32, 95% CI 1.72–3.15, p < 0.001), chronic kidney disease (OR 3.05, 95% CI 2.24–4.15, p < 0.001), and MNA score (OR 0.97, 95% CI 0.94-1.00, p = 0.031).

Conclusion

EAT-10 scale was independently associated with overt dehydration among older adults, as MNA score was. Correction of both dysphagia and malnutrition might improve overt dehydration to a better extent than correction either of these factors alone. Future studies are needed to test cause and effect relationships.

Background

Water, which constitutes approximately 60% of the adult body, is the most important nutrient for all living organisms. It plays a crucial role in thermoregulation, maintaining blood pressure, biochemical reactions, transportation of nutrients to cells, and removal of waste from cells. The water content in the body changes throughout life, being highest in infants and children and decreasing with age. The decrease in total body fluid, along with factors such as declining kidney function, medications, and mobility disorders, renders older adults at risk for dehydration [1, 2]. It affects approximately 20–30% of older adults and can reach prevalence rates of up to 50% in nursing home residents. Dehydration has outcomes that are more adverse in geriatric patients compared to young adults, increasing mortality and morbidity. Dehydration has also been associated with impaired cognitive performance. Studies conducted in adults have reported that water loss exceeding 2% of body weight negatively affects cognitive performance, including memory, attention, mathematical calculations, and perceptual motor speed. Dehydration in older adults often occurs due to reduced water intake, but excessive water loss can also be a contributing factor [2, 3]. Therefore, the risk factors of dehydration should be identified to prevent the development of these adverse clinical outcomes.

Oropharyngeal dysphagia (OD) is a common condition that affects approximately 27% of independent older adults and up to 51% of those residing in nursing homes. It is associated with malnutrition, dehydration, aspiration pneumonia, medication non-adherence, and increased healthcare costs [4]. In 2016, the European Society recognized OD as a geriatric syndrome for Swallowing Disorders and the European Geriatric Medicine Society [5, 6]. While the relationship between oropharyngeal dysphagia (difficulty swallowing) and pneumonia, malnutrition, and mortality have been recognized among older adults, relationship between dysphagia and dehydration have not been studied in detail in this population [7]. In studies conducted particularly in the post-acute stroke and hospitalized patient groups, it has been noted that aspiration pneumonia, dehydration, urinary tract infection, and constipation are common acute sequelae of stroke and are independently associated with dysphagia [8,9,10]. Although dehydration is considered one of the most important complications of OD in older individuals, further research needed in this area.

The aim of this study is to determine the frequency of dehydration in dysphagia in older patients, evaluate the relationship between these two conditions and identify risk factors for dysphagia.

Methodology

Study design

This was a cross-sectional study which included older patients. The study was conducted at the Department of Geriatric Medicine Clinicinauniversity hospital. The study has obtained ethical approval from the Non-Interventional Research Ethics Committee of our institution. (number: E-54022451-050.04-139645). This investigation adhered to the principles outlined in the Declaration of Helsinki. Informed consent was obtained from all patients or their legal representatives prior to their participation in the study.

Participants

A total of 2328 patients underwent comprehensive geriatric and swallowing assessments and were evaluated based on the inclusion and exclusion criteria outlined. All patients in the geriatric outpatient clinic were ≥ 60 years of age. All patients who volunteered to participate and had complete dysphagia assessment were included in the analysis. Patients who were unable to undergo dysphagia assessment were excluded from the study. Additionaly, patients who did not have a blood test including sodium, potassium, urea, and glucose, and therefore, could not have their plasma osmolality calculated, were excluded from the study.

Evaluations

Dehydration

We calculated the plasma osmolality based on the formula of Khajuria and Krahn as follows: ‘‘1.86 × (serum sodium + serum potassium) + 1.15 × plasma glucose + urea + 14’’ [11]. According to guidelines, a cut off level of > 295 mmol/L can be used for the definition of dehydration using the calculation method if direct measurement is not available [12]. We also used a cut off level of > 300 mmol/L to define overt dehydration, a more severe state of dehydration [13].

Eating assesment Tool (EAT-10)

The Eating Assessment Tool (EAT-10) is a patient-based questionnaire used in clinical swallowing evaluations to assess quality of life. The questionnaire consists of a total of 10 questions, which are scored by patients on a scale of 0 to 4. At the end of the questionnaire, the scores are added up to obtain the total EAT-10 score. EAT-10 is advantageous compared to other questionnaires used in swallowing assessments due to its simplicity, ease of scoring, and applicability to a wide range of diseases. It has been shown that EAT-10 provides objective evidence of swallowing dysfunction and predicts the risk of aspiration. If the EAT-10 score is 3 or higher, you may have problems swallowing efficiently and safely. It recommended discussing the EAT-10 results with a physician. The EAT-10 is a subjective screening tool that evaluates individuals’ self-perception of swallowing difficulty. In our study, we chose to use the EAT-10 due to its practicality and widespread use. The EAT-10 showed for OD 0.89 sensitivity and 0.82 specificity [14].

The patient’s demographic characteristics, comorbid diseases, the number of drugs were recorded. The anticholinergic burden was assessed using the anticholinergic burden (ACB) scale [15]. In the geriatric evaluation of patients who applied to the Geriatrics Clinic, Lawton-Brody Instrumental Activities of Daily Living (IADL) and Barthel Index (BI) for evaluation of daily living activities, Mini Nutritional Assessment (MNA) for evaluating nutritional status, and Geriatric Depression Scale (GDS) for depression level [14, 16,17,18,19,20]. Additionally, orthostatic blood pressures were measured for each patient [21]. Routine blood tests were requested at the first admission of the patients (serum glucose, creatinine, urea, albumin, calcium, phosphorus, potassium, complete blood count, Vitamin B12, thyroid stimulating hormone, folate) and recorded.

Statistical analysis

Quantitative variables are expressed in mean ± standard deviation. Categorical variables are expressed as proportions. Chi-squared tests or Fisher’s exact tests were used for the comparison of proportions, as appropriate. Groups were compared for means using the Mann–Whitney U test. Logistic regression analysis was performed to determine predictors of dysphagia in the geriatric cohort. In the first model, the dependent variable was selected as overt dehydration to use EAT-10 scale as a continuous variable and determine association between EAT-10 and overt dehydration. Adjustments were for age, sex, drug count, and common comorbidities. Another model was conducted to determine associations between dysphagia and common geriatric syndromes. Age, sex, and variables that had a p-value of < 0.05 for comparisons between patients’ dysphagia versus no dysphagia were included in the multivariate regression analysis. Results were expressed as odds ratios (ORs) and 95% confidence intervals. All the patients in the matched cohort had dysphagia based on Eat10 scale. Statistical analysis was performed using SPSS 22.0 version (IBM SPSS, Chicago, IL). A P value of < 0.05 was considered statistically significant. The significance level will be evaluated at p < 0.05. With a 5% margin of error and a standard effect size of 0.36, a minimum of 119 cases have been planned for our study [2].

Results

Of the 2062 patients evaluated, Posm and dysphagia assessment were not available in 607, and 110 patients, respectively. Among the remaining 1345 patients, 71% were female (950 patients) and the mean age was 78 ± 8. Characteristics of patients are summarized in Table 1.

Table 1 Characteristics of the geriatric cohort

Overall, dysphagia was defined in 361 (27%) patients. Posm was > 300 mmol/L in 310 (23%) patients and > 295 mmol/L in 753 (56%) of patients. Posm > 300 was found in 29% of patients with dysphagia, and 21% of patients with no dysphagia (p = 0.002). The rate of Posm > 295 mmol/L was 57% versus 55% in the same groups, respectively (p = 0.629). In this geriatric outpatient group, dysphagia was significantly associated with a plasma osmolarity of over 300 mmol/L (OR 1.53, 95% CI 1.16–2.01, p = 0.002), and this association remained significant after adjustments for age and sex (OR 1.49, 95% CI 1.13–1.96, p = 0.005). There was no significant association between the presence of dysphagia and a Posm > 295 mmol/L.

EAT-10 was used as a continuous variable, and predictors of overt dehydration were evaluated. Age, chronic kidney disease, diabetes mellitus, hypertension, ischemic heart disease, cerebrovascular disease, EAT-10 scale, number of drugs, and MNA score were associated with overt dehydration in univariate analysis (Table 2). These variables and sex were included in the multivariate regression model. Chronic kidney disease (OR 3.05, 95% CI 2.24–4.15, p < 0.001), diabetes mellitus (OR 2.32, 95% CI 1.72–3.15, p < 0.001), EAT-10 scale (OR 1.03, 95% CI 1.00-1.06, p = 0.038), and MNA score (OR 0.97, 95% CI 0.94-1.00, p = 0.031).

Table 2 Predictors of overt dehydration

Older age, ischemic heart disease, cerebrovascular disorders, Parkinson’s disease, higher number of drugs, exposure to anticholinergic drugs, and higher points in geriatric depression scale were found to be associated with dysphagia, while higher points in Barthel (BADL) index, Lawton (IADL) index, and MNA score, and higher levels of body-mass index, and estimated glomerular filtration rate were associated with a lower risk of dysphagia (Table 3). Along with age and sex, all these variables were included in the multivariate regression model. Higher number of drug exposure (OR 1.05, 95% CI 1.01–1.10; p = 0.025), Barthel index (OR 0.99, 95% CI 0.98–0.99; p < 0.001), and geriatric depression scale score (OR 1.09, 95% CI 1.05–1.13; p < 0.001) were found as independent predictors of dysphagia in the multivariate analysis.

Table 3 Factors associated with dysphagia among olders adults

Discussion

This cross-sectional study analysed the relationship between dehydration and swallowing difficulties in older adults. The study found that patients with oropharyngeal dysphagia accounted for up to 27% of the patients. The prevalence of dehydration according to a cut off level of 295 mmol/L was not significantly different between patients who had dysphagia versus those who did not. However, the prevalence of dehydration based on a cut of level of 300 mmol/L was significantly higher among older adults with dysphagia. Therefore, while dysphagia may not be the only factor related to dehydration, its presence appears to be associated with a more severe dehydration status. Interestingly, the significant association of overt dehydration and EAT-10 score was independent of nutritional state based on MNA score. MNA score was also found to be independently associated with overt dehydration. Thus, correction of both dysphagia and malnutrition may improve overt dehydration to a better extent than correction of either of these factors alone. Longitudinal studies are needed to test this hypothesis. Additional analysis in the present study demonstrated that dysphagia was associated with a higher number of drug exposure, higher risk of dependency based on basic activities of daily living, and geriatric depression in older patients.

Swallowing disorder leads to a range of clinical complications such as aspiration, inadequate nutrition, and dehydration. Despite being a common complication, dehydration receives little attention. With aging, dehydration, observed at a rate of 26–39%, is more common in elderly individuals having swallowing disorders [22]. Our findings indicate that there is a higher prevalence of dehydration (Posm > 300) in older individuals with swallowing difficulties compared to those without such difficulties who seek geriatric outpatient clinic (29% vs. 21%; 57% vs. 55% for Posm > 295). A recent study reported that the prevalence of dehydration was calculated to be 43.9% in patients’ dysphagia with when they accepted the cut of > Posm 295. The reason for the higher rate in our study may be that the average age of our patients is higher (78 years vs. 63 years). We determined that 55% (for Posm > 300) of older patients who sought care at the swallowing difficulties clinic had dehydration. These observed rates indicate that dehydration should not be neglected in geriatric cases and should be taken into consideration, especially in individuals with complaints of swallowing difficulties.

The main factors that contribute to dehydration risk, especially in the elderly, are listed as follows: changes in functional status, particularly mobility impairments and barriers; cognitive and communication disorders; feeding difficulties (oropharyngeal dysphagia); and medication effects [23]. According to the findings of the study conducted by Li et al., there is a high incidence of dehydration in patients with dysphagia. Advanced age, increased use of medications such as diuretics and beta-blockers, poorer functional status, and reduced fluid intake are significant factors contributing to dehydration in hospitalized patients with dysphagia [24]. Studies investigating the relationship between dysphagia and dehydration in the literature have mainly focused on stroke patients. Dysphagia, which is observed during the acute and chronic phases of stroke, can lead to dehydration due to changes in feeding patterns [25]. Additionally, neurogenic dysphagia, which develops because of the disease mechanism, is also believed to have an impact on dehydration [26]. In our study, acute stroke cases were excluded from the geriatric outpatient clinic included in our research. Previous studies have focused on investigating dysphagia in hospitalized centers rather than in outpatient populations. Our study is unique in that it establishes the relationship with dysphagia and is conducted in an outpatient setting.

The risk factors for dehydration in older adults are highly variable, and the more risk factors present, the higher the likelihood of dehydration. As older adults age, they experience a decrease in total body water percentage, which increases their susceptibility to dehydration. The decrease in compensatory responses to low blood pressure or blood volume further increases the risk of dehydration in older adults compared to younger adults. Unfortunately, certain medical conditions become more common in old age. Difficulty swallowing pills can be an indication of dysphagia, and the medications themselves can contribute to the problem. More than 2000 drugs can cause dry mouth (xerostomia) or affect lower oesophageal sphincter relaxation through anticholinergic mechanisms [27]. Additionally, our study found patients with dysphagia were more likely to have dependency on daily living activities (evaluated by Barthel index). There may be a bidirectional relationship between functional impairment and dysphagia. Dysphagic patients cannot consume enough fluid and food; which can lead the patients more dependent; on the other hand, patients with functional impairment may be dehydrated because they are more dependent on the caregiver for fluid consumption. Additionally, we found that depressive symptoms were more common in dysphagic patients. Indeed, dysphagia is independently associated with negative psychosocial health, and quality of life; can cause depression [28].

On the other hand, the relationship between oral frailty and sarcopenic dysphagia is particularly important in older adults. Literature suggests that oral frailty and sarcopenic dysphagia can negatively affect swallowing function, thereby reducing fluid intake, and contributing to dehydration. In older individuals, the decline in muscle mass and strength weakens the chewing and swallowing muscles, leading to swallowing difficulties (dysphagia). This makes fluid intake more challenging, increasing the risk of dehydration. Conversely, dysphagia and dehydration can also contribute to the progression of oral frailty and sarcopenic dysphagia. Dehydration can further weaken muscle strength, exacerbating sarcopenia, and when combined with malnutrition, can lead to the weakening of oral muscles. This vicious cycle can cause a progressive deterioration in swallowing function and worsen overall health in older individuals [29, 30].

We recognize the limitations of the present study. The cross-sectional design prevents us from establishing clear cause-and-effect relationships. As a result, it is difficult to fully assess whether outcomes such as dysphagia and dehydration are directly caused by specific risk factors. Although the EAT-10 has high specificity and sensitivity with instrumental swallowing tests, using it for diagnosing dysphagia is a limitation of our study. Future longitudinal studies which are used videofloroscopic swallowing studies would help to better understand the progression of these relationships over time. Our study focused solely on outpatients, which limits the generalizability of the findings. Outpatients typically represent a group with less severe clinical conditions, and it may be challenging to determine if the findings apply similarly to more severely ill populations, such as hospitalized or nursing home patients. Although the diagnosis of dehydration can be made based on calculation method as we did in the present study [12]. Lastly, the absence of direct assessment of oral frailty and sarcopenic dysphagia is another significant limitation of our study. Given the potential impact of these conditions on dysphagia and dehydration, particularly in the elderly population, not evaluating these factors may have restricted the depth of interpretation of our findings. This study has numerous strengths. This is the first study to provide comprehensive evidence on the dehydration of dysphagia in older adults, and its relationships between them. Second, the sample group size was large enough to make for a comprehensive study.

Conclusion

In conclusion, dysphagia was observed in one out of three older patients. Dysphagia was associated with a higher number of drug exposure, dependency on basic activities of daily living and geriatric depression. Posm > 300 was found in 29% of patients with dysphagia and 1.5 times higher in dysphagia compared to patients without dysphagia. Geriatric swallowing rehabilitation is the work of an interdisciplinary team, with the elderly person at the center and many health professionals such as patient relatives, caregivers, doctors, physiotherapists, nurses, speech therapists, occupational therapists, and psychologists. The aim is to increase function and reduce disabilities as much as possible through therapeutic approaches and to ensure the elderly person’s optimum quality of life and level of functional independence. Future research should use more objective methods, such as video fluoroscopy or fiber optic endoscopic evaluation, to assess swallowing function and improve the diagnosis and management of dysphagia. Since the current study is cross-sectional, it couldn’t examine the long-term effects of dysphagia and dehydration or how these conditions change over time. Therefore, longitudinal studies are needed to explore their progression with aging and to establish causal links. To better understand oral frailty and sarcopenic dysphagia, future studies should assess oral muscle strength, chewing ability, and overall muscle health, especially in older adults. Research should also focus on large, multicenter, prospective studies to clarify the connections between these factors and dysphagia. Finally, randomized controlled trials could evaluate the impact of nutritional interventions, exercise, and oral hygiene on swallowing function to identify the most effective prevention and treatment strategies.