The Critical Role of Thickeners in the Therapeutic Medical Management of People with Dysphagia

This article discusses the value of thickeners for patients suffering from “dysphagia,” a term used to describe difficulty in swallowing. The author covers the health risks of untreated dysphagia, particularly for geriatric populations, thickening agents for food and drinks, levels of thickness, the economic consequences of untreated dysphagia, prescriptions for treating dysphagia and supervision by qualified healthcare professionals and regulatory considerations from an EU perspective.
 
Introduction
 
The ability to eat and drink is fundamental to health and wellbeing. Dysphagia, the term used to describe difficulty in swallowing, has devastating consequences, such as malnutrition, dehydration, risk of chest infection, depression and social isolation. Dysphagia also can lead to life-threatening events, such as choking and acquiring pneumonia. While medications exist to treat heart disease, pain, blood pressure, thickening agents have a critical role in the therapeutic medical management of dysphagia. Appropriate treatment and management by a qualified healthcare professional is essential for obtaining the prescription of the appropriate thickener in the thickness level to best meet the person’s needs in terms of thickened liquid for hydration and medication transfer purposes. In addition, product access also relies on having thickeners fall under a clearly defined regulatory status as a Food for Special Medical Purposes (FSMP).
 
The elegance of the swallowing mechanism belies its complexity and in order to truly appreciate the challenges of dysphagia requires visualization of the system starting with the pharynx. It is a common housing of both the airway and the pathway for ingestion. As an analogy, the pharynx can be likened to a railway tunnel. It is tempting to think there are two distinct tunnels, with one leading always and only to the lungs, the other leading always and only to the stomach. However, this is not the case. The pharynx is a single tunnel with “track switching” capabilities. It reconfigures from its usual role as a conduit for air to travel from nose or mouth to airway and momentarily moves, adjusts and closes anatomic structures to protect the nasal passage and the entrance to the airway. It does this while simultaneously opening a valve to allow food and liquid to enter the oesophagus.

Poorly timed swallowing and breathing results in material entering the airway.
 
Muscles that move too slowly during the configuration process will allow liquids, in particular, to enter the airway. Thus, inefficient swallowing can result in residue being retained in naturally occurring sinuses in the pharynx, risking their inhalation into the lungs as the pharynx resumes its airway conduit role. In general, the airway closes for only one second for each swallow.
 
Dysphagia is a disorder of the digestive system recognized by the World Health Organisation (WHO) in the International Statistical Classification of Diseases and Related Health Problems (ICD-10), International Classification of Diseases 11th Revision (ICD-11) and the International Classification of Functioning, Disability and Health (ICF). While the ICD tools are used to classify death, the ICF classifies health. It is noteworthy that dysphagia is classified in both ICD and ICF tools. With swallowing occurring 500-700 times per day,¹ little thought is given to the process; there is an implicit trust that food, drink, saliva and medicine will pass uneventfully through the mouth, throat (pharynx) and oesophagus to arrive safely at the stomach and beyond for digestion.
 
 
The complexity of dysphagia is that it is a symptom of many disorders and can arise from structural, physiologic or neurologic conditions. Thus, its prevalence is often lost where the focus is on the primary diagnostic category such as stroke, dementia, cancer of the head and neck, etc. Unlike heart disease or respiratory disorders, dysphagia is a medical orphan, with no one medical group that purely specializes in the condition. Most often, speech pathologists are the healthcare professionals who assess and manage dysphagia while dietitians ensure people with dysphagia receive adequate nutrition and hydration.
 
Dysphagia affects individuals of all ages. However, there is a greater prevalence in the vulnerable populations at either end of life’s continuum—in infancy and old age. The condition affects about 25-55% of babies born prematurely, 60% of children with developmental disability, 85% of children with cerebral palsy, approximately 50% of stroke survivors and 84% of people with dementia.^2-6 Of concern, a US study found that of those adults with swallowing difficulties, only 37% were given a diagnosis and only 22% saw a health professional for their swallowing problem.⁷
 
Dysphagia: A Growing Concern for an Aging Population
 
The prevalence of dysphagia increases with advancing age, with 10-20% of individuals older than 65 estimated to have swallowing difficulties.⁸ This figure rises to 30-50% of residents in aged care facilities.⁹ As recently as 2017, the global population aged 60 years or more was 962 million and is anticipated to reach 2.1 billion by 2050. Accordingly, the demand for dysphagia treatment is set to soar.
 
Dysphagia is recognized as a symptom and geriatric syndrome by the European Society of Swallowing Disorders (ESSD) and the European Union Society of Geriatric Medicine (EUGMS).¹⁰ Their thorough and well-considered white paper eloquently argues for dysphagia as a ‘forgotten geriatric giant’ as it meets the definition of a clinical condition that is highly prevalent in old age; it is multifactorial in nature, associated with multiple co-morbidities and poor outcomes, and is best treated used a multidimensional approach. Indeed, dysphagia is much like the geriatric syndromes of falling and incontinence that are features of many disorders, but not a single diagnostic category of their own.
 
The world’s aging population has caused the WHO to focus sharply on healthy aging and the identification and prevention of frailty. Dysphagia has been identified as both a contributing factor to frailty and a consequence of it. Unsurprisingly, frailty increases with aging and, while 5% of 65 year olds are diagnosed as frail, this number increases to 26% of individuals by the age of 85 years.¹¹ Dysphagia is also a significant risk factor for the development of aspiration pneumonia in the frail elderly, with an OR of 9.84 (95% CI 4.15-23.33).¹² Aspiration pneumonia most often develops due to micro-aspiration or frank aspiration of bacteria carried on saliva, food and liquids, in combination with impaired cough and host immune function.¹³
 
Thickeners: The Main Therapeutic Pillar of Dysphagia
 
In a discussion of the ICF used in dysphagia management, Threats¹⁴ described the four goals for dysphagia assessment and intervention as providing the following:
 

1. adequate nutrition and hydration
2. decreased risk of aspiration related illness
3. decreased choking risk
4. decreased risk of psychosocial effects such as social isolation or depression in persons with dysphagia

 
Tablets, pills, capsules and liquid medication are the mainstay of modern medicine and used to manage a range of medical conditions such as blood pressure, arthritis, pain, depression and infection. However, there are no pharmaceutical capsules, pills or tablets to treat dysphagia. In fact, for a person with dysphagia to swallow medication to treat their primary disorder (e.g., heart disease), it is a challenge. The main therapeutic pillar of dysphagia management is the modification of foods and drinks to ensure they can be swallowed safely and efficiently without entering or lodging in the airway, causing catastrophic results. While food can be mechanically modified as pureed, minced or chopped into bite-size pieces to alleviate choking risk, the safe consumption of liquids necessitates the use of thickening agents.
 
The fast movement of thin liquids, such as water, tea and coffee, increases risk of airway invasion for people who are unable to hold liquids in their mouth, those with a slow or irregular swallow response, those with a poor ability to reconfigure the pharynx to protect the airway and those with reduced insight or cognitive awareness of their difficulties. Consequently, liquids are modified by thickening to slow their flow and to reduce the likelihood that they will fracture and travel to the airway and the esophagus simultaneously or become lodged in the pharynx, risking inhalation of the residue into the airway as normal breathing resumes. However, recent research demonstrates that it is more than thickness providing the therapeutic value to thickened liquids. With liquids, the bolus head moves faster than the tail, resulting in a stretching of the liquid that influences bolus flow. Various thickening agents have different filament stretching profiles.¹⁵ Some thickened liquids stretch and hold together especially well as they flow through the pharynx, reducing their likelihood to fracture and spill apart while in transit to the oesophagus.
 
Efficacy of Thick Fluids as a Treatment for Dysphagia
 
Two independent systematic reviews of the literature concluded that thickening liquids is efficacious in the treatment of dysphagia. Both studies found that increasing bolus viscosity results in increased swallowing safety. Steele, et al.,¹⁶ found that there is a therapeutic limit to thickness after which residue is more likely to occur. Newman, et al.,¹⁷ and Steele, et al.,¹⁸ determined that increased oral or pharyngeal residue may increase post-swallow airway invasion. This occurs when the residual material is drawn into the airway when the pharynx is reconfigured from food/drink ingestion pathway to air pathway. Although further research is needed, preliminary data from independent studies suggests that at a liquid thickness that is 1500 times as thick as water or greater (>1500 mPas), produces significantly more residue in the mouth and pharynx than textures 300 times as thick as water (300 mPas).^19,20
 
While both systematic reviews agreed that thickening liquids increases swallowing safety, they differed in their discussion of the exact number of therapeutic thickness gradations and their thickness levels. Newman, et al.,²¹ described three levels of thickness, adopting the nomenclature and definitions of the US based National Dysphagia Diet to demonstrate a reduction in penetration-aspiration with increasing liquid thickness. Steele, et al.,²² stated that the available evidence does not provide a clear indication of how many incremental levels of increasing viscosity might be clinically meaningful. The authors cited that very few studies provided objectives measures of their stimulus characteristics with considerable variability in measurements and reporting variables. An international survey of clinical practice summarized that five or fewer levels of drink thickness are currently in clinical use in the management of dysphagia based on data from more than 2000 respondents in 33 countries.²³ Steele, et al.,²⁴ and Newman, et al.,²⁵ encouraged further research to clearly describe thickness levels that repeatedly yield therapeutic benefits to people with dysphagia. Both Steele, et al.,²⁶ and Newman, et al.,²⁷ also agreed that properties other than liquid thickness, such as yield stress, density, cohesiveness and slipperiness may influence swallowing physiology and function.
 
Specialized and Complex Properties of Thickeners Used in the Treatment of Dysphagia
 
The development of thickening agents specifically for the treatment of dysphagia has advanced over the years. Although food agents, such as flour, corn starch and tapioca have for centuries been used to thicken culinary items such as sauces and gravies, these items are unsuitable as thickening agents for people with dysphagia. Flour and corn starch clump. They are difficult to prepare, requiring heat to help them swell and absorb water. They are unstable, losing their thickness with prolonged stirring, heating or when mixed with acids (e.g., lemon juice). Early thickening agents used for dysphagia in the 1990s used modified starch that overcame the heating process to allow powdered starch to be added to cold beverages for thickening purposes. However, research published circa 2005 demonstrated problems with stability of starch based thickening agents. Garcia, et al.,²⁸ found that 80% of samples thickened with starch-based thickeners became thicker 10 minutes following the standard wait time and one-third thicker again 30 minutes post the standard wait time. In contrast, the gum-based thickeners maintained their thickness level at the end of standard waiting time and 10 and 30 minutes post standard waiting time. Similar results were reported by Matta, et al.,²⁹ confirming good stability of gum-based thickeners.
 
Recent research has provided deeper enquiry into ionic and microstructural interactions of gum thickeners with dietary liquids and medicine microarchitecture. Gums cause liquids to become thicker by causing meshes of entanglement that water molecules become lodged in; however, gums differ in their ionic charge.³⁰ While guar gum and locust bean gum are negatively charged, carrageen holds a negative charge and xanthan gum a highly negative charge. This has implications for thickening nutrient rich liquids, such as milk, where calcium holds a positive ionic charge. Indeed Hadde, et al.,³¹ demonstrated that ionic interactions between xanthan gum and milk caused a delay to the thickening process, while the protein in milk increased the final viscosity of the liquid. These results are not confined to dietary liquids and have the potential to impact medication bioavailability. This emerging work clearly shows that thickeners should be prescribed by healthcare professionals along with a call for strong inter-disciplinary collaborations to ensure medication efficacy for oral medicines for people with dysphagia.
 
The microstructural properties of thickening agents also are critical to how they flow and hold together during swallowing. This information is provided by the field of extensional rheology. To date, much of the scientific assessment of the thickness of liquids has focussed on shear rheology or resistance to flow. Studies examining the midpoint of a thick fluid filament stretched between two plates show the microstructure associated with the thickening agent affects the integrity of the stretched sample. When examined microscopically, starch thickeners result in clusters of swollen balloon-like starch molecules. These balloon-like structures are prone to filament breakage during extensional testing. Conversely, gum thickeners cause webs of entangled molecules, creating an enhanced filament thinning ability that allows stretching without breakage.³² Despite sharing a similar shear viscosity or measure of thickness, the ability of starch and gum thickened liquids to hold together when stretched is very different. For individuals with dysphagia, this property of stretching without breaking and potentially leaving residue is very important. Although both starch and gum-based thickeners improve swallowing safety, starch thickened liquids have been found to result in post-swallow residue that does not occur with gum thickened liquids in stroke survivors with dysphagia.³³
 
This is not to say that one type of thickening agent is best for all situations. In fact, based on the information above, a case could be made for using xanthan gum-based thickeners for the provision of most thick liquids for hydration purposes, and consideration of guar or other gums for use with milk and liquids for which xanthan gum may have ionic interactions. The filament breakage characteristics of starch thickeners may improve bioavailability of thick medications. The digestive breakdown mechanism for the different thickening agents also needs to be considered. Starch is broken down in all phases of digestion, starting with the mouth with amylase progressing through hydrolytic enzymes in the stomach, and further processing in the small intestine where water and nutrients are absorbed. In contrast, gums tend to pass through the upper phases of digestion without effect, relying on the microflora of the large intestines to break them down.
 
Complications of Untreated Dysphagia
 
The prescription of thickeners reduces aspiration risk in people with dysphagia and helps prevent common complications, such as dehydration, pneumonia, reduced quality of life and economic burden. Individuals with untreated dysphagia are at risk of dehydration. Difficulty coordinating oral containment or inability to control liquid rushing into the pharynx before it has been reconfigured to safely guide it to the oesophagus, can result in intractable coughing, choking and discomfort.
 
Dehydration increases the risk of renal failure, impaired mental status, falls, urinary tract infection, constipation, medication toxicity, respiratory infection, decreased muscle strength and bed sores.³⁴ Dehydration is a common finding for individuals with dysphagia.^35,36 Although initial concerns of the cause of dehydration associated with dysphagia related to water binding capacity of thickeners, studies have demonstrated in both animal and human models that water thickened, even to extremely thick level and regardless of thickening agent, does not affect the bioavailability of water, with 95% being rapidly absorbed and equilibrated within 60 minutes.³⁷ Difficulty opening drink containers, trouble accessing staff to assist with drinking, reduction in thirst associated with the aging process, xerostomia as a side effect of polypharmacy and lack of mouth wetness as a signal of thirst quenching have all been raised in discussions of persistent dehydration in people with dysphagia.³⁸
 
Pneumonia
 
Only recently have researchers used multiple-cause mortality data based on ICD codes to estimate deaths from fatal pulmonary complications for people who died with stroke. Traditional cause-specific mortality data is based on the underlying cause of death, defined as the disease or injury that initiated the events leading to death. In the case of stroke, the traditional cause of death would be ‘stroke’ and data associated with ‘aspiration pneumonia’ or ‘choking by food’ would not be captured. Using multiple cause of death capture, Chang, et al.,³⁹ estimated that the incidence of dying from aspiration pneumonia was 5% (~12,000 deaths per year) and death from choking around 1.5 % (~3700 deaths per year) with 0.5% reporting both aspiration and choking as a cause of death for people with stroke. During the 2001-2010 period surveyed, increasing age and male gender increased the odds associated with death from aspiration pneumonia and choking in individuals with stroke. Hu, et al.,⁴⁰ reported on autopsy findings of individuals in whom aspiration was the immediate cause of death and, likewise, found age and male status as key findings. The most common precipitating factors for aspiration were depressed consciousness (46%) and dysphagia (44%). Of concern, aspiration was not clinically suspected for 33% of the cohort. In these cases, the clinical diagnosis for immediate cause of death was pneumonia, neurologic disorder, sepsis and heart failure. These cases highlight the need for better awareness of dysphagia, prompt screening and management by a suitably trained healthcare professional.
 
Poor Quality of Life
Dysphagia is associated with social isolation with 36-100% of aged care residents avoiding eating with others, becoming embarrassed during meals and up to a quarter becoming anxious or panicky. Dysphagia and depression also have been positively correlated.⁴¹ In a cohort of community-dwelling individuals with dysphagia anxiety was diagnosed in 37%, clinically relevant symptoms of depression were identified in 32%, and 47% of the cohort showed affective symptoms.⁴² In addition to the person affected by dysphagia, the quality of life of their care-giver is also significantly impacted.⁴³ Spouses of individuals 65 years or older with dysphagia are twice as likely to report emotional burden, with 70% rating that burden as “moderate” to “severe.”⁴⁴
 
Economic Costs
 
Due to the many different conditions associated with dysphagia, economic data is often difficult to obtain. The move to recognize it as a Geriatric Syndrome would be welcome for increasing awareness and uncovering the true costs associated with the condition. Using ICD-9 coding, Altman, et al.,⁴⁵ found that in a 12-month period, 272,000 admissions of 77 million had dysphagia. The median hospitalization was four days compared with 2.04 days without a dysphagia diagnosis. Dysphagia was most commonly associated with fluid or electrolyte disorders, esophageal disease, stroke, aspiration pneumonia, urinary tract infection and congestive heart failure. Individuals over age 75 had a double the risk of dysphagia. Mortality was 13 times higher in patients with dysphagia in a rehabilitation setting compared to those without dysphagia. The rise in popularity of health economics research is yielding recent and sobering figures. More recent data demonstrates that patients presenting to hospital with dysphagia incur 40.36% greater costs than those without dysphagia, with increased length of stay in line with Altman and colleagues. Attrill, et al.,⁴⁶ reports an actual cost of $12,700 attributable to dysphagia based on their assessment of 11 studies that reported North American cost data. European data gathered in Denmark for individuals 60 years and older demonstrated that hospitalized patients with dysphagia had costs $4,200 (3,677 EUR) higher than those without a dysphagia diagnosis, while annual healthcare costs for those living with dysphagia in the community were $7209 (6,192 EUR) higher than those without.⁴⁷
 
Altman and colleagues⁴⁸ recommended early identification and use of a validated dysphagia screening tool to reduce length of stay and morbidly. Hinchey, et al.,⁴⁹ demonstrated that hospital-wide dysphagia screening programs reduce risk of pneumonia three-fold. Validated stroke specific and general dysphagia screening tools exist.⁵⁰ Early identification and management of dysphagia by a qualified healthcare professional reduced the complications identified above.
 
Thickeners as a Prescription by a Suitably Qualified Healthcare Professional
 
The prevalence of thickened fluid use has only been studied comprehensively in aged care. Of more than 25,000 elders living in a nursing home, up to 28% of individuals received thickened liquids (mean of 8.3%) for therapeutic management of dysphagia. Of these, most received the equivalent of mildly thick liquids (30-60%), 18-33% received the equivalent of moderately thick liquids and a small group received extremely thick liquids (6-12%).⁵¹ Although this data was gathered in Canada, the pattern of prescribing is consistent with other published clinician prescription rates in Australia over a range of clinical settings.^52,53
 
Thickness level can be likened to medication dose. Typically, slightly or mildly thick liquids are used for mild dysphagia management, while increasingly thicker liquids are used to manage more severe or complex forms of dysphagia. There are five gradations of thickness ranging from thin to extremely thick liquids used internationally in the management of dysphagia across adult and paediatric populations.⁵⁴ Healthcare professionals regularly monitor swallowing safety, adjusting thickness level according to improvement or deterioration in function. Stroke survivors might commence on extremely thick liquids but progress to mildly thick liquids as their conditions improves. Conversely, individuals with progressive neurological disorders such as dementia or Parkinson’s disease might initially require slightly thick fluids and then thicker drinks as their condition deteriorates.
 
As noted in the preceding section, thick liquids are not benign. Liquids that are too thick result in residue that can be aspirated; liquids that are too thin also will invade the airway. A liquid that is too thick or requiring too much effort to initiate flow has a profound impact on infants where a liquid too thick may require more physiologic effort to extract from the teat/nipple than the energy gained from the liquid ingested. Many individuals recovering from surgery, chemo or radiotherapy for treatment of cancer of the head and neck require liquids that flow slowly, but that do not require significant oral manipulation.⁵⁵ Healthcare professionals require a good clinical understanding of the person’s swallowing function, the most suitable thickness level for swallowing safety and hydration and the properties of the thickener best suited to that person’s needs. The optimal thickness level is person-specific and prescribed after considered clinical evaluation.
 
Compliance with thick liquids is better than with thinner liquids.⁵⁶ Better compliance means better hydration, and better hydration means faster recovery. Regular review of swallowing status allows qualified health professionals to adjust thickness levels promptly to ensure both swallowing safety and hydration needs are being met. In rehabilitation, the ultimate goal is to return the person to regular drinks as soon as they are able. In palliation, the goal is to slowly alter drink thickness to preserve dignity and quality of life for as long as possible. Healthcare professionals also must educate people with dysphagia as to appropriate methods of preparing thick drinks according to their personal thickness prescription. The care needed with this education can best be provided with an example. While people returning home might be tempted to assume that doubling or tripling the dose of thickener would result in a thick fluid that is double or triple the original thickness level, this is not correct. For example, at a 1% concentration of xanthan + dextrin solution, the thickness is reported to be 180 mPas. At 2% concentration, the thickness increases to 510 mPas and at 3% concentration is 790 mPas showing a logarithmic rather than a linear increase in thickness with increasing amounts of thickener.⁵⁷ Thickness is not the only property that is important with yield stress or the force needed to break down the internal structure so that the fluid will flow, also important to flow properties. In the example provided above, the yield stress also rises in a log fashion, requiring greater effort to initiate movement or flow. Shim, et al.,⁵⁸ found outpatients were less likely to be compliant with thick liquid prescriptions than inpatients. Lack of understanding of the importance of correct thickening to prescription may be a causative factor in this finding.
 
Section b5105 of the ICF describes swallowing as the function of clearing food and drink through the oral cavity, pharynx and oesophagus into the stomach at an appropriate rate and speed. Inter-disciplinary care is critical. Thickening liquids for hydration purposes is well understood by healthcare professionals; however, an understanding of the issues surrounding oral administration of medicine to people with dysphagia is still emerging. The complexities of interactions between thickening agents and medication active ingredients or their excipients are being uncovered. Inter-disciplinary research and clinical practice is required to ensure people with dysphagia receive liquids that are the correct thickness for their needs and medication that is in a form both safe to swallow and effective. Where this is not possible, consideration needs to be given to alternative medication formulations or to an alternative route of administration than the oral route.
 
The Economic Benefits of Dysphagia Care
 
The economic benefits of dysphagia care using a specialized healthcare professional have been demonstrated. UK data reported the annual cost of chest infection requiring hospital admission with routine care was 1.8 times more expensive than chest infections requiring hospitalization that included speech pathology care. Annual costs were reduced to £26.1 million ($33.2 million) from £48.2 million ($61.3 million). In community care, costs of treating chest infection reduced from £3 million ($3.8 million) with usual care to £1.6 million ($2 million) with speech pathology care. Marsh, et al.,⁵⁹ determined that every £1 ($1.2) invested in speech language therapy generated £2.3 ($2.9) in healthcare cost savings through avoided cases of chest infection.
 
Regulatory Considerations: A European Perspective
 
Thickeners and thickened liquids “for the dietary management of dysphagia” are regulated in the EU as Food for Special Medical Purposes (FSMPs).
 
FSMPs are recognized as a specialized category of foods intended to be used by vulnerable patient populations, where specific legislation is critical to ensure FSMPs are appropriately labelled and marketed for their intended use. Without this specific categorization of food, it is difficult to ensure appropriate information getting to the patient and healthcare professional.
 
FSMPs are defined in article 2(2)(g) of framework Regulation (EU) 609/2013. “FSMP means food specially processed or formulated and intended for the dietary management of patients, including infants, to be used under medical supervision; it is intended for the exclusive or partial feeding of patients with a limited, impaired or disturbed capacity to take, digest, absorb, metabolise or excrete ordinary food or certain nutrients contained therein, or metabolites, or with other medically-determined nutrient requirements, whose dietary management cannot be achieved by modification of the normal diet alone.”⁶⁰
 
The regulatory environment of FSMPs in the EU has been previously well-described by Bushell.⁶¹ The authors show the definition of FSMPS is broad enough to encompass a wide variety of FSMPs necessary to meet the specific nutritional needs of many diseases, including dysphagia. All elements of the FSMP definition must be taken into consideration, and no one element should be considered in isolation to include or exclude a product from this category.
 
Taken together the above, thickeners and thickened liquids for the dietary management of dysphagia meet the definition of Food for Special Medical Purposes.
 

• Different from other food agents with thickening properties such as flour, corn-starch and tapioca, thickeners based on starch or gums are specifically processed in order to achieve a stable and appropriate texture free of lumps which is safe to be swallowed by patients suffering of dysphagia.
• The use of thickeners under medical supervision is of paramount importance for the safety of the patient. Thickeners are the main therapeutic pillar for dysphagia management regardless of healthcare or community setting and regardless of age. Appropriate treatment and management by a qualified healthcare professional is essential for the prescription of the appropriate thickener and thickness level to best meet the person’s needs from their thickened liquid for hydration and medication transfer purposes.
• As elaborated above, the intended use of thickeners is to enable safe feeding of dysphagia patients, who cannot eat ordinary food or drinks without the risk of aspiration, helping to prevent common complications such as dehydration, pneumonia, reduced quality of life and economic burden.
• The measure of whether it is possible to achieve the required nutritional intake by modification of the normal diet must be considered in the context of the patient and the challenges of their disease or medical condition. The Commission Notice on the Classification of Food for Special Medical Purposes⁶² explains FSMPs may offer nutritional and clinical advantages to patients over and above a modification of the normal diet alone. This must be taken into account, even if to some extent a modification of the normal diet may address the nutritional requirements of dysphagia patients.

 
Conclusion
 
Thickening agents are vital for the medical management of people with dysphagia who are often medically fragile and at risk of dehydration and malnutrition. Thickeners have dosages that provide optimal benefit for people with dysphagia once assessed by suitably trained healthcare professionals. Early identification and inter-disciplinary care of individuals with dysphagia is advocated.
 
FSMPs are a food category specially formulated or processed to meet the medically determined nutrient requirements of patients with a disease, disorder or medical condition. Taken together, when viewed in this manner, thickeners and thickened liquids meet the requirements of Food for Special Medical Purposes in the EU.
 
References
 

1. Lear C, Flanagan J and Moorrees C. “The Frequency of Deglutition in man. Arch Oral Biol. 1965;10:83-99.
2. Benfer K, Weir K, Bell K, Ware R, Davies P and Boyd R. “Orohayngeal Dysphagia and Gross Motor Skills in Children With Cerebral Palsy.” Pediatrics. 2013;131:e1553-e1562.
3. Mercado-Deane MG, Burton E, Harlow S, Glover A, Deane D, Guill M and Hudosn V. “Swallowing Dysfunction in Infants Less Than 1 Year of age.” Pediatric Radiology. 2001;31,423- 428.
4. Giudice E, Staiano A, Capono G, Romano A, Florimonte L, Miele E, Ciarla C, Campanozzi A and Crisanto A. “Gastrointestinal Manifestations in Children With Cerebral Palsy.” Brain and Development. 1999;21:307-311.
5. Martino R, Silver F, Teasell R, Bayley M, Nicholson G, Streiner DL and Diamant NE. “The Toronto Bedside Swallowing Screening Test (TOR-BSST) Development and Validation of a Dysphagia Screening Tool for Patients With Stroke.” Stroke. 2009;40:555-561.
6. Horner J, Alberts M, Dawson D, Cook G. “Swallowing in Alzheimer’s Disease.” Alzheimer’s Disease and Associated Disorders. 1994;8:177-189.
7. Bhattacharyya N. “The Prevalence of Dysphagia Among Adults in the United States.” Otolaryngology Head and Neck Surgery. 2014;151:765-769.
8. Barczi S, Sullivan P and Robbins J. “How should dysphagia care of older adults differ? Establishing Optimal Practice Patterns.” Seminars in Speech and Language. 2000;21: 347-361.
9. Kayser-Jones K and Pengilly K. “Dysphagia Among Nursing Home Residents.” Geriatr Nurs. 1999;20:77–84.
10. Baijens L, Clave P, Cras P, Ekberg O, Forster A, Kolb G, Leners JC, Masiero S, Mateos-Nozal J, Ortega O, Smithard D, Speyer R and Walshe M. “European Society for Swallow Disorders- European Union Geriatric Medicine Society White Paper: Oropharyngeal Dysphagia as a Geriatric Syndrome.” Clinician Interventions in Aging. 2016;11:1403-1428.
11. Fried L, Tangen C, Walston J, Newman A, Hirsch C, Gottdiener J, Seeman T, Tracy R, Kop W and Burke G. “Frailty in Older Adults: Evidence for a Phenotype.” J. Gerontol. A Biol. Sci. Med. Sci. 2001;56:M146–M156. doi:10.1093/Gerona/56.3.M146. Accessed 5 June 2019.
12. Van der Maarel-Wierink C, Vanobbergen J, Bronkhorst E, Schols J and de Baat C. “Meta-Analysis of Dysphagia and Aspiration Pneumonia in Frail Elders.” J. Dent. Res. 2011;90:1398–1404. doi:10.1177/0022034511422909.
13. Langmore S, Terpenning M, Schork A, Chen Y, Murray J, Lopatin D and Loesche W. “Predictors of Aspiration Pneumonia: How important is dysphagia?” Dysphagia. 1998;13: 69–81. doi:10.1007/PL00009559.
14. Threats T. “Use of the ICF in Dysphagia Management.” Seminars in Speech and Language. 2007;28:323-333.
15. Hadde E and Chen J. “Shear and Extensional Rheological Characterization of Thickened Fluid for Dysphagia Management.” J of Food Engineering. 2019;245:18-23.
16. Steele C, Alsanei W, Ayanikalath S, Barbon C, Chen J, Cichero J, Coutts K, Dantas R, Duivestein J, Giosa L, Hanson B, Lam P, Lecko C, Leigh C, Nagy A, Namasivayam A, Nascimento W, Odendaal I, Smith C and Wang H. “The Influence of Food Texture and Liquid Consistency Modification on Swallowing Physiology and Function: A Systematic Review.” Dysphagia. 2015;30(1):2-26. doi:10.1007/s00455-014-9578-x. http://bit.ly/1wvZydp. Accessed 5 June 2019.
17. Newman R, Vilardell N, Clave P and Speyer R. “Effect of Bolus Viscosity on the Safety and Efficacy of Swallowing and the Kinematic Response in Patients With Oropharyngeal Dysphagia: White Paper by the European Society of Swallowing Disorders (ESSD).” Dysphagia. 2016;31:232-249.
18. Op cit 16.
19. Hind J, Divyak E, Zielinski J, Taylor A, Hartman M, Gangnon R and Robbins J “Comparison of Standardized Bariums With Varying Rheological Parameters on Swallowing Kinematics in Males.” JRRD. 2012;49:1399-1404.
20. Robbins J, Gensler G, Logemann J, Lindblad A, Brandt D, Baum H, Lilienfeld D, Kosek S, Lundy D, Dikeman K, Kazandijian M, Gramigna G, McGarvey-Toler S and Miller Gardner P. “Comparison of Two Interventions for Liquid Aspiration on Pneumonia Incidence. Ann of Intern. Med. 2008;148:509-518.
21. Op cit 17.
22. Op cit 16.
23. Cichero J, Lam P, Steele C, Hanson B, Chen J, Dantas R, Duivestein J, Kayashita J, Lecko C, Murray J, Pillay M, Riquelme L and Stanschus S. “Development of International Terminology and Definitions for Texture-Modified Foods and Thickened Fluids Used in Dysphagia Management: The IDDSI Framework.” Dysphagia. 2017;32:293-314. https://link.springer.com/article/10.1007/s00455-016-9758-y. Accessed 5 June 2019.
24. Op cit 16.
25. Op cit 17.
26. Op cit 16.
27. Op cit 17.
28. Garcia J, Chambers E and Matta Z. “Viscosity Measures of Nectar- and Honey-Thick Liquids: Product, Liquid and Time Comparisons.” Dysphagia. 2005;20:325–35.
29. Matta Z, Chamber E and Garcia J. “Sensory Characteristics of Beverages Prepared With Commercial Thickeners Used for Dysphagia Diets.” J Am Diet Assoc. 2006;106,1049–54.
30. Sharpe K, Ward L, Cichero J, Sopade P and Halley P.” Thickened Fluids and Water Absorption in Rats and Humans.” Dysphagia. 2007;22:193–203.
31. Hadde E, Nicholson T, Cichero J and Deblauwe C. “Rheological Characterisation of Thickened Milk Components (Protein, Lactose and Minerals). J of Food Eng. 2015;166:263-267.
32. Ibid.
33. Vilardell N, Rofes L, Arreola V, Speyer R and Clave P. “A Comparative Study Between Modified Starch and gum Thickeners in Post-Stroke Oropharyngeal Dysphagia.” Dysphagia. 2016;31:169-179.
34. Wotton K, Crannitch K and Munt R. “Prevalence, Risk Factors and Strategies to Prevent Dehydration in Older Adults.” Contemp Nurse. 2008;31:44–56.
35. Castellanos VH, Butler E, Gluch L and Burke B. “Use of Thickened Liquids in Skilled Nursing Facilities.” J Am Diet Assoc. 2004;104:1222–1226.
36. Cichero J. “Thickening Agents Used for Dysphagia Management: Effect on Bioavailability of Water, Medication and Feelings of Satiety.” 2013. Nutrition Journal. 12:54. http://www.nutritionj.com/content/12/1/54. Accessed 5 June 2019.
37. Op cit 30.
38. Op cit 36.
39. Chang CY, Cheng TJ, Lin C, Chen JY, Lu TH and Kawachi I. “Reporting of Aspiration Pneumonia or Choking as a Cause of Death in Patients who Died With Stroke. Strok. 2013;44:1182-1185.
40. Hu X, Yi E and Ryu J. “Aspiration-Related Deaths in 57 Consecutive Patients: Autopsy Study.” Plos One. 2014;9,e103795.
41. Holland G, Jayasekeran V, Pendelton N, Horan M, Jones M and Hamdy S. “Prevalence and Symptom Profiling of Oropharyngeal Dysphagia in a Community Dwelling of an Elderly Population: A Self-Reporting Survey. Dis Esophagus. 2011;24: 476-480.
42. Verdonschot R, Baijens L, Serroyen J, Leue C and Kremer B. “Symptoms of Anxiety and Depression Assessed With the Hospital Anxiety and Depression Scale in Patients With Oropharyngeal Dysphagia.” J of Psychosomatic Res. 2013;75:451-455.
43. Kyle G. “Managing Dysphagia in Older People With Dementia.” British Journal of Community Nursing. 2011;16:6-10.
44. Shune S and Namasivayam-MacDonald A. “Swallowing Impairments Increase Emotional Burden in Spousal Caregivers of Older Adults.” J of Appl. Gerontology. 2019. doi:10.1177/07334648188217787.
45. Altman K, Yu GP and Schaeffer S “Consequence of Dysphagia in the Hospitalized Patient: Impact on Prognosis and Hospital Resources.” Arch Otolaryngol Head Neck Surg. 2010;136:784-789.
46. Attrill A, White S, Murray J, Hammond S and Doeltgen S. “Impact of Oropharyngeal Dysphagia on Healthcare Cost and Length of Stay in Hospital: A Systematic Review.” MBC Health Services Research. 2018;18: 594.
47. Westmark S, Melgaard D, Rethmeier L and Ehlers L. “The Cost of Dysphagia in Geriatric Patients.” ClinicoEconomics and Outcomes Research. 2018;10:321-326.
48. Op cit 45.
49. Hinchey JA, Shephard T, Furie K, Smith D, Wang D and Tonn S. “Formal Dysphagia Screening Protocols Prevent Pneumonia.” Stroke. 2005;36:1972–1976.
50. Cichero J, Heaton S and Bassett L. “Triaging Dysphagia: Nurse Screening for Dysphagia in an Acute Hospital.” Journal of Clinical Nursing. 2009;18:1649-1659. doi:10.1111/j.1365-2702.2009.02797.x.
51. Op cit 35.
52. Op cit 5.
53. Atherton M, Bellis-Smith N, Cichero J and Suter M. “Texture-Modified Foods and Thickened Fluids as Used for Individuals With Dysphagia: Australian Standardised Labels and Definitions.” Nutrition and Dietetics. 2007;64(Suppl. 2): S53-S76. doi:10.1111/j.1747-0080.2007.00153.x.
54. Op cit. 23.
55. Logemann J. Evaluation and Treatment of Swallowing Disorders (2nd edition). Texas: Pro-ed, Inc. 1998.
56. McGrail A and Kelchner LN. “Adequate Oral Fluid Intake in Hospitalised Stroke Patients: Does viscosity matter?” Rehab Nursing. 2012;37(5):252–257.
57. Seo CW and Yoo B. “Steady and Dynamic Shear Rheological Properties of gum-Based Food Thickeners Used for Diet Modification of Patients With Dysphagia: Effect of Concentration.” Dysphagia. 2013;28:205-211.
58. Shim J, Oh B and Han T. “Factors Associated With Compliance With Viscosity-Modified Diet Among Dysphagia Patients.” Ann Rehabil Med. 2013;37:628-632.
59. Marsh K, Bertani’s E, Suominen H and Venkatachalam M. “Matrix Evidence: An Economic Evaluation of Speech and Language Therapy.” Report for the Royal College of Speech Language Therapists UK. 2010.
60. Regulation (EU) No 609/2013 of the European Parliament and of the Council of 12 June 2013 on Food Intended for Infants and Young Children, Food for Special Medical Purposes, and Total Diet Replacement for Weight Control.
61. Bushell C and Ruthsatz M. “Revising the EU FSMP Regulatory Framework: Laying a Foundation for Nutritional Patient Care.” Regulatory Focus. July 2018.
62. Commission Notice on the Classification of Food for Special Medical Purposes (2017/C 401/01), Official Journal of the European Union. http://www.fsai.ie/uploadedFiles/CNotice_2017_C401_01.pdf. Accessed 12 May 2019.

 
About the Author
 
Julie Cichero, PhD, is co-chair of the International Dysphagia Diet Standardisation Initiative that seeks to improve the safety of people with dysphagia through common terminology for texture modified food and thickened drinks. Both a clinician and a researcher, Cichero is internationally recognized for her work in promoting interdisciplinary collaborations with chemical engineering, pharmacy, food oral processing, dietetics, speech pathology, nursing and medicine. She is currently employed as the Human Research Ethics Committee Liaison Officer at Mater Research, MML, Brisbane Australia. She can be contacted at Julie.cichero@iddsi.org.
 
Cite as: Cichero J. “The Critical Role of Thickeners in the Therapeutic Medical Management of People with Dysphagia.” Regulatory Focus. June 2019. Regulatory Affairs Professionals Society.