Dysphagia https://doi.org/10.1007/s00455-021-10283-7 ORIGINAL ARTICLE White Paper by the European Society for Swallowing Disorders: Screening and Non‑instrumental Assessment for Dysphagia in Adults Renée Speyer1,2,3 · Reinie Cordier2,4 · Daniele Farneti5 · Weslania Nascimento6 · Walmari Pilz7,8 · Eric Verin9 · Margaret Walshe10 · Virginie Woisard11,12 Received: 7 January 2021 / Accepted: 8 March 2021 © The Author(s) 2021 Abstract This White Paper by the European Society for Swallowing Disorders (ESSD) reports on the current state of screening and non-instrumental assessment for dysphagia in adults. An overview is provided on the measures that are available, and how to select screening tools and assessments. Emphasis is placed on different types of screening, patient-reported measures, assessment of anatomy and physiology of the swallowing act, and clinical swallowing evaluation. Many screening and non- instrumental assessments are available for evaluating dysphagia in adults; however, their use may not be warranted due to poor diagnostic performance or lacking robust psychometric properties. This white paper provides recommendations on how to select best evidence-based screening tools and non-instrumental assessments for use in clinical practice targeting different constructs, target populations and respondents, based on criteria for diagnostic performance, psychometric properties (reli- ability, validity, and responsiveness), and feasibility. In addition, gaps in research that need to be addressed in future studies are discussed. The following recommendations are made: (1) discontinue the use of non-validated dysphagia screening tools and assessments; (2) implement screening using tools that have optimal diagnostic performance in selected populations that are at risk of dysphagia, such as stroke patients, frail older persons, patients with progressive neurological diseases, persons with cerebral palsy, and patients with head and neck cancer; (3) implement measures that demonstrate robust psychometric properties; and (4) provide quality training in dysphagia screening and assessment to all clinicians involved in the care and management of persons with dysphagia. Keywords Measures · Diagnostic accuracy · Validity · Reliability · Responsiveness · Psychometrics * Renée Speyer renee.speyer@isp.uio.no 1 Department Special Needs Education, University of Oslo, Oslo, Norway 2 7 School of Occupational Therapy, Social Work and Speech Department of Otorhinolaryngology, Head and Neck Pathology, Faculty of Health Sciences, Curtin University, Surgery, Maastricht University Medical Center, Maastricht, Perth, Australia The Netherlands 3 8 Department of Otorhinolaryngology and Head and Neck School for Mental Health and Neuroscience, Maastricht Surgery, Leiden University Medical Centre, Leiden, University, Maastricht, The Netherlands The Netherlands 9 Dept of Physical and Rehabilitation Medicine, Rouen 4 University Hospital, Rouen, France Department Social Work, Education and Community Wellbeing, Northumbria University, Newcastle upon Tyne, 10 Department of Clinical Speech and Language Studies, Trinity UK College Dublin, Dublin, Ireland 5 Audiologic Phoniatric Service, ENT Department, AUSL 11 Voice and Deglutition Unit, Department Romagna, Infermi Hospital, Rimini, Italy of Otorhinolaryngology and Head and Neck Surgery, Larrey 6 Hospital, University Hospital of Toulouse, Toulouse, France Gastrointestinal Physiology Laboratory, Department of Surgery, Hospital de Mataró, Universitat Autònoma de 12 Oncorehabilitation Unit, Toulouse Universitary Cancer Barcelona, Mataró, Spain Institute, Oncopole Hospital, Toulouse, France 13 Vol.:(0123456789) R. Speyer et al.: White Paper by the European Society for Swallowing Disorders Introduction with variable sequelae and using different measures to determine the presence of dysphagia. The impacts of defi- The terms Dysphagia and swallowing disorders are used nitional issues on determining accurate prevalence rates interchangeably in the literature; however, achieving are twofold. First, definitional inconsistencies will have international consensus on defining dysphagia is more an impact on aspects of validity, reliability, and gener- challenging. Despite there being no universally accepted alizability of prevalence numbers. Second, screening or definition, a commonly used description of dysphagia is assessments of dysphagia operationalizes the underlying the dysfunction of one or more parts of the swallowing construct being measured, and definitional inconsisten- apparatus including the mouth, the tongue, the oral cavity, cies will invariably influence what and how dysphagia is the pharynx, the airway, and the oesophagus and its upper being measured. Despite the implications of definitional and lower sphincters, often due to anatomical or struc- challenges, given the high prevalence of dysphagia [6, 7], tural deficiencies or abnormalities [1]. Swallowing is not the serious complications associated with it, and costs to only essential for nutritional intake, but it is also directly healthcare [8], systematic screening of at-risk populations involved in the management of internal secretions from such as acute stroke patients should be central to health- the upper and lower aerodigestive tracts (e.g. saliva, bile, care strategies to improve early intervention and clinical and nasal, tracheal or bronchial secretions). Dysphagia is outcomes in these clinical populations. Moreover, the high associated with a broad spectrum of underlying congenital prevalence of dysphagia underscores the need for stand- or acquired conditions which is influenced by both age and ardized, reliable, and valid methods for the screening and comorbid diseases [2]. Dysphagia is one of the leading assessment of dysphagia. causes of death and morbidity for older persons, children The purpose of screening is to identify persons at risk of and adults with neurological disorders (e.g. cerebral palsy, dysphagia. Patients who are identified as being at risk through stroke, dementia), or head and neck cancer patients, due to screening are typically referred for further assessment and, serious complications such as malnutrition, dehydration, where needed, related assessment including oral health and and aspiration pneumonia [3, 4]. gastroesophageal reflux. Both screening and assessment need Dysphagia is a symptom or collection of symptoms to be evidence-based and feasible to administer. Only screen- resulting from underlying impairments and disorders in ing with sufficient diagnostic performance and assessments the highly integrated neuromotor sequence of swallowing, with robust psychometric properties should be used clinically from forming a cortical decision through to the realiza- and in research. For example, using screening tools with poor tion of motor action with associated sensory modulation, diagnostic performance may result in missing people at risk defined by series of events that involve the digestive and for dysphagia (false positives) or lead to unnecessary use of upper respiratory tract and the interaction of various ana- limited resources by assessing those who are not at risk of dys- tomical structures along the pathway [5]. Dysphagia may phagia (false negatives). Similarly, implementing assessments modify the preparation, propulsion, and/or transit of the with poor psychometric qualities will undermine evidence- bolus through the upper digestive pathways and reflects based practice and research as current health status or interven- abnormalities in transit and/or airway protection. A dis- tion effects cannot be objectified if measures lack robustness tinction can be made between oropharyngeal and oesopha- in validity, reliability, or responsiveness [9, 10]. Selecting the geal dysphagia. best evidence-based screening and assessments for dysphagia Not having reached consensus on a universal defini- is an essential step in the management of dysphagia. tion of the construct of dysphagia impacts on making an The purpose of this white paper by the European Soci- accurate estimation of the prevalence of dysphagia, as ety for Swallowing Disorders (ESSD) is to report on the it influences what criteria need to be met to fall within current state of screening and non-instrumental assessment the parameters of the definition. A systematic review on for dysphagia in adults. The measures that are available, the prevalence of dysphagia in the general population how to select screening tools and assessments, and gaps in indicated marked variability in prevalence rates, which research that still need to be addressed in future research ranged between 2.3 and 16% [6]. Another review dem- will be discussed. onstrated that the prevalence of dysphagia after stroke and in patients with Parkinson’s disease, traumatic brain injury, and community-acquired pneumonia was high Screening (8.1–80%, 11–81%, 27–30%, and 91.7%, respectively) [7]. The high variability in the retrieved prevalence data Screening in a Nutshell can be explained by discrepancies regarding dysphagia definitions, underlying diseases being at different stages Screening is generally accepted as the first step in the man- agement of dysphagia by identifying patients at risk for 13 R. Speyer et al.: White Paper by the European Society for Swallowing Disorders Fig. 1  Flow chart for selection of screening tools and clinical assessments 13 R. Speyer et al.: White Paper by the European Society for Swallowing Disorders swallowing problems (see Fig. 1). Being identified as at voice changes seem to rule out risk of aspiration, whereas risk of dysphagia following screening indicates the need small volumes with single sips indicate aspiration when for further assessment. A great variety of different types of clinical signs are present [14]. screening has been described in the literature. Many screen- All patients at risk of dysphagia should be screened. ing tools consist of trial swallows using water in various Common populations at risk are frail older persons, stroke aliquots or a range of different viscosities. Other forms of patients, patients with progressive neurological diseases screening utilize combined protocols of trial swallows and (e.g. Parkinson’s disease or dementia), children and adults pulse oximetry, pulse oximetry alone, evaluating clinical with non-progressive neurodevelopmental conditions (e.g. features (e.g. abnormal gag, voice alteration, or volitional cerebral palsy), and patients with head and neck cancer [7, cough), cervical auscultation, and elements of medical his- 19, 20]. Patients failing screening should be referred for fur- tory (e.g. recurrent episodes of pneumonia or cough elicita- ther assessment by a dysphagia expert. However, patients tion tests) [11, 12]. In addition, screening tools may use dif- having an established risk for dysphagia or manifest signs of ferent endpoints to define being at risk, such as penetration, dysphagia through case history may be referred for further aspiration, pharyngeal delay, or dysphagia. assessment without being subjected to screening. If patients Screening tools using multiple swallow trials may differ cannot be screened due to their cognitive state or health con- in the order of selected viscosities or selected volumes per dition, screening should be postponed, usually resulting in swallow trial. For example, the Toronto Bedside Swallowing recommended nil per os while waiting for screening. Some Screening Test or TOR-BSST [13] consists of two steps; the patient groups, however, may follow different screening and first step is screening for abnormalities in voice quality and assessment pathways as no improvement in their condition tongue movement, and the second step consists of ten con- is to be expected, for example, patients who may be at risk secutive teaspoons of water. Any failed item during either of dysphagia and have progressive cognitive decline (e.g. the first or second step constitutes a positive screen result dementia). The lack of consensus and guidelines on how to and indicates an increased risk for dysphagia and a need to manage these vulnerable populations result in moral dilem- referral for assessment. Authors of water swallow screening mas that need to be resolved on a case-by-case basis between tools may argue that the rationale for screening is solely to healthcare practitioners and patients’ family. In comparison, identify persons at risk of dysphagia and, therefore, no other screening is usually recommended to be performed within consistencies need to be included[14]. the first 24 h following the stroke [21]; however, there is no Conversely, the volume–viscosity swallowing test or international consensus on what should be the critical time- V-VST [15], another commonly used screening, uses three frame for screening in other diagnostic groups. different viscosities (referred to as nectar, liquid, and pud- ding) and three volumes (5, 10 and 20 ml), resulting in a Selection Criteria for Screening maximum of nine swallow trials. Whereas the TOR-BSST screens for being at risk for dysphagia only, the V-VST pro- Screening needs to meet the following feasibility criteria vides additional oral intake advice. Still, as only single trials before being implemented in clinical settings: simple admin- are used per volume–viscosity combination, any advice on istration, use of non-invasive methods to minimize distress oral intake should be made with caution, as using a lim- to patients, and straightforward to train clinicians involved ited number of swallow trials can underestimate the aspira- [22, 23]. While most screening tools are freely available, tion risk in persons with dysphagia, especially when using some, like the TOR-BSST, can only be used after attending boluses with a thin liquid consistency [16]. Even when a an online training module to improve standardization and screening tool uses several trials of the same volume and consistency in rating. viscosity, for example the Gugging Swallowing Screen or Screening tools need to be valid, reliable, and show good GUSS [17], any advice on oral intake should nevertheless diagnostic performance. Screening tools can be developed be supported by findings from further assessment. and validated for specific target populations (e.g. patients There is still no consensus on the order in which different after stroke, patients with head and neck cancer or frail older viscosities should be offered when expanding the water pro- persons). The use of certain screening tools may not be rec- tocol with, for example, thickened liquids, puddings, or solid ommended in other patient groups than the populations for boluses. Some authors start with thickened liquids using which the screen was originally developed and validated for; increased patient safety in terms of reduced frequency of validity of a screening must be confirmed again when its use aspiration as rationale, whereas other authors prefer starting is extended to other clinical populations. Sufficient intra- with thin liquids referring to the heightened risk of residue rater, inter-rater, or test–retest reliability is often expressed when using higher viscosities [18]. Also, the use of different by an intra-class correlation coefficient (ICC) or weighted volumes may impact screening results; consecutive sips with Kappa equal to or greater than 0.70 [24]. Diagnostic per- large volumes in patients without overt airway responses or formance of a screening tool is determined by comparison 13 R. Speyer et al.: White Paper by the European Society for Swallowing Disorders Table 1  Diagnostic performance: terms, acronyms, and definitions [26] Term [Acronym] Definition Formulaa Prevalence [PR] Proportion of subjects in a population having a disease Diseased / Total population Sensitivity [Se] Proportion of reference test positive (diseased) subjects who test Se = TP / (TP + FN) positive with the screening tool Specificity [Sp] Proportion of reference test negative (healthy) subjects who test Sp = TN / (TN + FP) negative with the screening tool Positive Predictive Value [PPV] Proportion of positive results in statistics and diagnostic tests that PPV = TP / (TP + FP) are true positive results Negative Predictive Value [NPV] Proportion of negative results in statistics and diagnostic tests that NPV = TN / (TN + FN) are true negative results Positive Likelihood Ratio [LR +] Probability of a person who has the disease testing positive divided LR +  = Se / (100 – Sp) by the probability of a person who does not have the disease test- ing positive Negative Likelihood Ratio [LR-] Probability of a person who has the disease testing negative divided LR- = (100 – Se) / Sp by the probability of a person who does not have the disease test- ing negative Diagnostic Odds Ratio [DOR] Odds of a positive test in those with disease relative to the odds of a DOR = LR + / LR- positive test in those without disease Error % of observations that were misclassified by the model (FP + FN) / (TP + TN + FP + FN) Accuracy % of observations that were correctly classified by the model (TP + TN) / (TP + TN + FP + FN) = 100 – error Precision Proportion of TP to all positive predictions TP / (TP + FP) = PPV a TP = True Positive = Identified patient; FP = False Positive = Healthy person identified as patient (Not identified healthy person); TN = True Negative = Identified healthy person; FN = False Negative = Patient identified as healthy person (Not identified patient) with a reference test, usually fiberoptic endoscopic evalua- sensitivity and specificity refer to how well the screen- tion of swallowing (FEES) or videofluoroscopic evaluation ing tool identifies the presence and absence of dysphagia, of swallowing (VFS). According to the international COn- respectively, whereas predictive values are the probability sensus-based Standards for the selection of health Meas- that a positive or negative test result is accurate. As such, urement INstruments (COSMIN), this is also referred to as sensitivity and specificity provide clinicians information criterion validity [25]. The reference test is considered the about which screening to select, whereas predictive values ‘gold standard’ and hypothesized to have no false negative or inform the persons being tested about the chances of actually false positive results. In other words, the ‘gold standard’ cor- having dysphagia. rectly indicates the presence of dysphagia when the person Depending on work environment and requirements, dif- truly has dysphagia (true positives) and identifies subjects ferent cut-offs for diagnostic performance may be used. as not having dysphagia when they truly do not have dys- For example, if assessment after screening is expensive or phagia (true negatives). As such, it is not recommended to invasive, clinicians may prefer to minimize the number of use another screening or clinical assessment as reference test false positives and use a cut-point with high specificity. Con- unless considered a ‘gold standard’. Furthermore, both refer- versely, if the penalty for missing a case is high (e.g. the ence tests and screening tools may use different endpoints. disease is fatal but can be treated successfully), a clinician For example, when administering a FEES, the occurrence of may prefer to maximizing the number of true positives by aspiration may be used as endpoint to confirm the diagnosis using a cut-point with high sensitivity. In general, tests with of dysphagia, whereas a water swallow screening may use high sensitivity have low specificity; they are good for iden- coughing or a wet voice as endpoint for identifying a patient tifying actual cases of the disease but often at the expense at risk of dysphagia. As different endpoints yield different of high rates of false positives. For example, results from diagnostic performance, clinicians and researchers must pre- a meta-analysis showed that increasing volumes in water define and select endpoints before determining diagnostic swallow tests resulted in higher sensitivity but lower speci- performance. ficity when screening for aspiration in stroke patients [27]. Diagnostic performance comprises elements such as There are, however, no strict guidelines on the optimal cut- sensitivity, specificity, positive and negative predictive offs for diagnostic performance. Some diagnostic reviews value, positive and negative likelihood ratio, and diagnostic only included screening tools with a high sensitivity (at least odds ratio (Table 1) [26]. As applied to the topic at hand, 70%) and at least a moderate specificity (at least 60%; e.g. 13 R. Speyer et al.: White Paper by the European Society for Swallowing Disorders [11, 12]). Even so, guidelines on what cut-off scores to use Clinical assessment may refer to a large variety of assess- remain ambiguous. ments, each of which may be describing different aspects A receiver operating characteristics (ROC) curve, a prob- of dysphagia. In the absence of systematic reviews, text- ability curve, visualizes the trade-off between sensitivity and books and current opinion papers provide different over- specificity by presenting the true positive rate (sensitivity) views. While there is currently no comprehensive overview as function of the false positive rate (100 minus specific- of clinical assessments, most literature seems to agree on ity). Conversely, the area under the curve (AUC) can be the following four categories: 1) assessment of cognition interpreted as the average value of sensitivity for all pos- and communication; 2) evaluation of the oral, laryngeal, sible values of specificity or the average value of specificity and pharyngeal anatomy, physiology, and function (includ- for all possible values of sensitivity [28]. AUC represents ing cranial nerve examination); 3) oral intake and nutritional a measure of separability; how well is the model capable of status; mealtime observations; and 4) intervention trials (e.g. distinguishing between two classes or groups, for example, bolus modification, postural adjustments and/or swallow between persons with or without dysphagia? The COSMIN manoeuvers) [22, 31]. guidelines stipulate that an AUC of at least 0.70 (or 70%) is Another form of non-instrumental clinical assessment required to provide evidence for sufficient criterion validity involves patient self-report measures as part of the multi- [24]. dimensional assessment of dysphagia. Patient self-report measures target two distinct but related concepts: functional health status (FHS) versus health-related quality of life (HR- Non‑Instrumental Assessment QoL). FHS refers to the influence of a given disease (e.g. dysphagia) on particular functional aspects, whereas HR- Assessment in a Nutshell QoL is the unique personal perception of someone’s health, taking into account social, functional, and psychological After a patient has been screened for dysphagia and identi- issues [32]. fied as being at risk for dysphagia, further assessment is required (Fig. 1). Both ‘gold standard’ assessments VFS Patient‑Reported Measures and FEES can diagnose aspiration (including silent aspira- tion) and other physiological problems in the pharyngeal Patient-reported measures play an important role in patient- phase. However, access to instrumental assessment may be centred healthcare and can improve communication, patient restricted and no international consensus exists regarding engagement, and self-efficacy as patients may be more which visuoperceptual or software-based measures to use involved in goal setting [33–35]. The use of a patient- for analysis of these video recordings. Moreover, there is reported measure, however, may be limited by patients insufficient psychometric evidence to recommend any indi- who experience cognitive and/or language comprehension vidual measure as valid and reliable to interpret VFS and deficits. Recently, a framework (patient-reported outcome FEES recordings [29]. measures or PROM-cycle) was developed to support the Another step after screening is non-instrumental clinical selection and implementation of patient-reported measures assessment by a dysphagia expert. In the process of clinical in individual patient care and for quality improvement [35]. assessment of dysphagia, many different aspects may be dis- The PROM-cycle describes eight steps necessary for sys- tinguished, for example, medical history: conducting a phys- tematic selection and implementation of PROMs in a cyclic ical examination; the subjective description of the swallow- approach and provides links to, for example, relevant tools ing problem or patients’ complaints [30]; and the expert’s and existing guidelines, examples from clinical practice and clinical observations during the interview and examination methodological considerations. process. Clinical assessment may have the following pur- Patient self-report measures in dysphagia often combine poses, single or in combination: to identify possible causes both FHS and HR-QoL in the same measure, even though of the swallowing problems; to estimate the safety of swal- both are considered two distinct concepts. Consequently, lowing and risk of aspiration; to support decisions on oral disease-related functioning cannot be distinguished from or alternative feeding routes; to identify the need for further disease-related quality of life as subjectively experienced assessment (e.g. instrumental assessment); and to establish by patients. Further, psychometric reviews on patient self- baseline data for future comparisons after intervention or evaluation (e.g. [36, 37]) and psychometric evaluations on during the course of a disease [22]. Clinical assessment may most commonly used self-report measures in dysphagia also address patient needs that are specific to certain clinical (e.g. [38–42]) identified that all existing measures have populations. For example, in patients with head and neck either poor psychometric properties or lack comprehensive cancer, the effects of radiation and chemotherapy may be evaluation and reporting of psychometric properties. This important and need to be described in detail. flags an urgent need for research. For example, even though 13 R. Speyer et al.: White Paper by the European Society for Swallowing Disorders the Eating Assessment Tool (EAT-10) is one of the most and validated GERD Impact Scale (GIS [63]) and the Reflux commonly used FHS measure in dysphagia, recent evidence Disease Questionnaire (RDQ [64]). Still, in the absence of using contemporary Item Response Theory1 (IRT; Rasch further psychometric evaluations, many of these measures analyses [43, 44]) did not support its use in either research or may not meet psychometric quality criteria [65]. clinical practice [38, 40–42]. Another frequently used FHS questionnaire is the Sydney Swallow Questionnaire (SSQ Assessment of Anatomy and Physiology [45]), which is yet to be evaluated using IRT. Among those self-report measures mainly targeting Before assessing the anatomy and physiology of the swal- HR-QoL are the Swallowing Quality of Life questionnaire lowing act, some higher cortical functions that act as precur- (SWAL-QOL [46]), the Dysphagia Handicap Index (DHI sors to oral feeding need to be evaluated. These include, but [47]), the Deglutition Handicap Index (DHI [48]), and the are not limited to, the patient’s alertness, responsiveness, MD Anderson Dysphagia Inventory (MDADI [49]). The cognition and language skills, as well as head and trunk SWAL-QoL, like the EAT-10, is one of few measures that control (i.e. motor control) [66]. In the absence of stand- has been evaluated using Rasch analyses. As an outcome of ardized formal assessments, input–output reasoning will the evaluation, it was recommended to further investigate inform further clinical assessment of functional anatomy the SWAL-QoL’s underlying structure and psychometric (Table 2–3) whereby innervation (input) from a muscle or characteristics prior to continued clinical use [39, 50]. For functional groups of muscles (effectors) will, in turn, result most self-report measures, however, even though their use in deglutition-related actions (output). is common practice, their psychometric robustness is yet to A strict order of events provides clinical markers that be established using IRT [36, 37]. guide clinicians during assessment with a functional–ana- The use of self-report measures for oral health has gained tomic pathway of motor outputs activated by sensory inputs importance in recent years. Poor oral health and concomitant (Table 2) [67]. Therefore, the anatomy and physiology that dysphagia are important risk factors of aspiration pneumo- underpins the swallowing act need to be understood to allow nia [51]. Oropharyngeal colonization by respiratory patho- for the assessment thereof. Swallowing is a highly integrated gens has shown to play a key role in the pathophysiology of neuro-sensorimotor function, realized by organs (effectors) aspiration pneumonia [52–56]. A recent systematic review affiliated with different systems and inter-linked with other reporting on patient-reported measures for oral health in functions, so that swallowing, breathing, and phonoarticu- adults identified 20 English-language multiple-item ques- lation alternate according to hierarchically correlated path- tionnaires summarized into four domains: oral function, oro- ways [68]. Swallowing is the result of external (sight and facial pain, orofacial appearance, and psychosocial impact smell) and internal sensory stimuli (touch, temperature, and [57]. Examples of frequently used self-report measures in taste), which converge at the meduallary swallowing cen- oral health include the Oral Health Impact Profile (OHIP tre, from where the motor efferents of the bulbar cranial [58]) and the Oral Health Questionnaire for Adults [59]. nerves (CNs) start: CN V (Trigeminal nerve: motor), CN Most self-reported measures in oral health, however, need VII (Facial nerve), CN IX (Glossopharyngeal nerve), CN further psychometric evaluation before supporting their X (Vagus nerve), CN XII (Hypoglossal nerve), and cer- implementation in healthcare and research [57]. vical spinal nerves C1-C3. The CN XI (accessory nerve) Given that gastroesophageal reflux disease (GERD) carries motor fibres for the sternocleidomastoid muscle is common in populations presenting with dysphagia [2, and trapezius muscles (spinal root), and parasympathetic 60, 61], self-report on GERD may form part of dysphagia preganglionic visceral fibres (cranial root) that join the CN assessment. Many examples can be found in the review by X reaching the soft palate, pharynx, larynx, and oesophagus. Bolier, Kessing [62] including, for example, the widely used The brainstem swallowing centre is widely connected and receives cortical, subcortical, thalamic, limbic and cerebel- lar descending modulatory afferents, which transform the 1 Methodologies and interpretation of Classic Test Theory (CTT) semi-reflex nature of swallowing into spatiotemporal inte- findings are easier to interpret than those of Item Response Theory grated muscular contractions (muscular patterns) [5]. The (IRT); however, the CTT framework has some limitations. In IRT the neurological structures (including cortex, extrapyramidal unit of analysis and results are not restricted to the test population, and pyramidal system, and cranial nerves) are contained in whereas in CTT the evaluation of psychometric properties is spe- cific to the test population. In addition, IRT evaluates the reliability the neurocranium (protective shell surrounding the brain and of each individual item, while CTT assesses the performance of a brain stem), while the swallowing effectors are contained in measure as a whole [43]. IRT models estimate both item and person the viscerocranium (skeleton supporting facial structure). parameters within the same model, calculate person-free parameter At this level, the upper parts of the respiratory and digestive estimation and item-free trait level estimation, and identify optimal scaling of individual differences based on the evaluation of differen- tract are arranged in parallel and conjugate in the pharyngeal tial item functioning [44]. cavity, which becomes a common pathway for both air and 13 R. Speyer et al.: White Paper by the European Society for Swallowing Disorders Table 2  Simplified overview of effectors of swallowing: input–output reasoning for clinical assessment of functional anatomy [111] Input aAfferents Effector Outputa Efferents V2 (maxillary nerve), V3 (lingual nerve: branch of inferior Lips VII (Labial sphincter) alveolar nerve of the mandibular nerve) V3 (lingual nerve: branch of mandibular nerve) Tongue XII (Oral control of bolus) V3 (mandibular nerve) Jaw V motor (Mastication) V, IX Soft palate V, X (Palate function) V Mouth and cheeks V motor, VII (Oral control of bolus) IX Base of tongue XII (Propulsion into oropharynx) X Epiglottis (lingual side) X (Laryngeal sphincter function) X (superior laryngeal nerve) Epiglottis (laryngeal side) X (Laryngeal sphincter function) X (superior laryngeal nerve) Glottis and supraglottal larynx X (Laryngeal sphincter function) X (inferior laryngeal nerve) Subglottal larynx X (Laryngeal sphincter function) X Cervical trachea X (Cough reflex) V, IX, X Naso-oropharynx IX, X (Velopharyngeal sphincter function) X Hypopharynx X (Propulsion, pharyngeal squeeze) a Cranial Nerves: I Olfactory nerve, II Optic nerve, III Oculomotor nerve, IV Trochlear nerve, V Trigeminal nerve, VI Abducens nerve, VII Facial nerve, VIII Vestibulocochlear nerve, IX Glossopharyngeal nerve, X Vagus nerve, XI Accessory nerve, XII Hypoglossal nerve bolus transport. In this way, the pharynx acts alternately as low-tech devices can be used to test thermal and gustatory an organ of the respiratory tract (chamber for air passage) as sensibility by wetting them in hot or iced water, or in salty, well as an organ of the digestive tract (peristaltic contracting sweet, bitter, sour, or sparkling solutions. chamber for bolus passage). Tone and strength of the tongue can be assessed by elic- Anatomy of the upper digestive tract allows the organi- iting resistance against a tongue blade, while mobility is zation of functional chambers operating in a concatenated assessed by administering non-articulatory or articulatory series [69]. In the oral cavity, the bolus is prepared (minced praxis tasks. The opening of the jaws (temporomandibu- and mixed with saliva) as a consequence of coordinated lar joint) is closely examined and masticatory muscles are actions between facial muscles, cheeks, teeth, jaws, tongue, evaluated for its praxis and strength. The pterygoid muscles and oral floor muscles [70]. When the bolus is transported are tested during lateral mandibular movements with the into the pharyngeal cavity, a reflex reconfiguration of the jaw applying resistance against a hand, while the masseter pharynx occurs; the oropharynx transforms from a respira- and temporal muscles can be palpated during contraction. tory pathway to a swallow pathway [71]. The pharynx acts The symmetrical soft palate movement is evaluated using as a digestive lumen, generating contractile and peristal- a simple articulatory task (i.e. by sustaining the vowel /a:/) tic activities with the aim of transporting the bolus to the or during the process of testing sensibility. The gag reflex oesophagus [72]. A strict hierarchy between vital primor- can be elicited by stimulating the back of pharynx with a dial reflex activities determines the arrest of respiration tongue blade/probe. Finally, the presence of the pharyngeal (apnea), thus allowing the pharyngeal transportation of the reflex is elicited by asking patients to perform a dry swallow bolus [73]. The reconfiguration of the pharynx is defined by while the clinician holds three fingers on the external hypo- glossopalatal opening, velopharyngeal closure, upper and laryngeal axis; the index finger is placed on the hyoid bone, anterior hyoid laryngeal excursion, and upper oesophageal the middle finger is placed on the thyroid notch, and the sphincter opening. ring finger is placed on the cricoid ring. There should be an Articulation and voice quality are checked during speech antero-superior displacement of these structures of about 2 and sustained vowel production and provide information to 2.5 cm during a dry swallow. Table 3 provides additional about vocal fold or glottis closure. Furthermore, facial examples of clinical assessment of functional anatomy and appearance and expression may indicate concerns about physiology of the swallowing act. orofacial musculature, presence of surgical scarring, asym- metry, and inadequate labial seal (drooling). Touch, temper- Clinical Swallowing Evaluation ature, and taste sensibility can be tested on the lips, mucosa of the oral cavity, tongue (body, base, margins), fauci, soft A clinical swallowing evaluation (CSE) is typically per- palate, and posterior wall of the oropharynx using low-tech formed after screening for swallowing problems to pro- devices such as a wisp of cotton or tongue blade. The same vide additional information to ascertain the relative risk 13 R. Speyer et al.: White Paper by the European Society for Swallowing Disorders Table 3  Simplified overview of input, effector, output, and clinical assessment for each functional group involved in deglutition (e.g. [109–111]) Functional group Motor Input Effector Output Innervationa (Main) Muscles (Main) Actions in Deglutition Masticatory CN V Lateral / Lateral pterygoid Mastication Masseter Closure oral cavity Temporalis Mandible: raise Facial CN VII Buccinator Lip/mouth: seal Orbicularis oris Bolus: push towards teeth Intrinsic tongue CN XII Inferior / Superior longitudinal Tongue: shorten – lengthen, narrow – broaden, tip Transverse up –down, concave – convex bow tongue Verticalis Bolus: preparation, formation, positioning, transport Extrinsic tongue CN X Palatoglossus Tongue: protrude – retract, lower – raise Bolus: preparation, formation, positioning, transport CN XII Genioglossus Seal oral cavity Hyoglossus Styloglossus Suprahyoid CN V Anterior belly of digastric Hyoid: lower – raise, protract – retract, stabilize Mylohyoid Mouth floor: stabilize, elongate Mandible: lower CN VII Posterior belly of digastric Stylohyoid C1 [via CN XII] Geniohyoid Infrahyoid C1 [via CN XII] Thyrohyoid Hyoid: lower, stabilize Mouth floor: stabilize, elongate Larynx: raise – lower, stabilize C1-C3 [via Ansa cervi- Omohyoid calis CN XII] Sternohyoid Sternothyroid Palatal CN V Tensor veli palatine Soft palate: raise – retract, lower, brace, tense Oropharynx entrance: widen CN X Levator veli palatin Posterior tongue: raise Palatoglossus Uvula: raise Seal back of oral cavity from oropharynx CN XI [via CN X] Uvular Seal nasopharynx Pharyngeal CN IX Stylopharyngeus Palate: lower Pharynx: raise, shorten CN X Palatopharyngeus Larynx: raise Salpingopharyngeus Seal oral cavity Superior / Middle / Inferior pharyngeal Seal nasal cavity constrictor Narrow pharyngeal lumen Bolus: transport Oesophageal sphincter: most distal component (of pharyngo-oesophageal segment or PES) Laryngeal CN X Aryepiglottic Vocal folds: adduct – open Lateral / posterior cricoarytenoid Arythenoids cartilages: approximate to epiglottis Oblique / Transverse arytenoid Epiglottis: lower Thyroarytenoid Aryepiglottic ­foldsb Thyroepiglottic a Cranial Nerves: I Olfactory nerve, II Optic nerve, III Oculomotor nerve, IV Trochlear nerve, V Trigeminal nerve, VI Abducens nerve, VII Facial nerve, VIII Vestibulocochlear nerve, IX Glossopharyngeal nerve, X Vagus nerve, XI Accessory nerve, XII Hypoglossal nerve b Laryngeal sphincter function or squeeze: true vocal folds, false vocal folds, aryepiglottic folds 13 R. Speyer et al.: White Paper by the European Society for Swallowing Disorders for aspiration and to direct clinical decision making [74]. trials with small 5 ml volumes of water, gradually increas- CSE findings are important in determining whether an ing the volume before moving to thicker consistencies. The instrumental assessment may be required (if not already rationale is that water, if aspirated, combined with good oral performed) and to decide which compensatory strategies hygiene will be absorbed into the lungs without the immedi- and postural manoeuvres need to be prioritized for tri- ate risk for the development of pneumonia [84, 85]. Other alling to inform dysphagia therapy planning and patient clinicians prefer to start with thickened consistencies so as to management. At least a tentative diagnosis must be made reduce the risk for aspiration [15]. Trials with fluids that pro- and a management plan agreed upon following a CSE [31]. mote sensation, for example carbonation and sweet and sour However, aspiration and other physiological problems in bolus, may be included in CSE [86–88]. The temperature of the pharyngeal phase of swallowing can only be diagnosed the bolus may also be manipulated with colder boluses used through directly observation using instrumental assess- to increase sensation [89]. Thicker consistencies may be tri- ments [75–77]. alled later as they may give rise to residue in the pharynx The initial step in a CSE is to compile a thorough case which, in turn, can lead to aspiration [18]. When assessing history with the patient and/or carer. This involves a care- chewing it is important to evaluate the patient’s ability to ful review of the medical history, if available, a history of manage solids and to identify risk of choking also. Assess- the present condition (e.g. onset, duration of difficulties, ments such as the Test of Mastication and Swallowing of symptoms), current swallowing status (e.g. method of oral Solids (TOMASS [90]) may be useful. intake and current diet, strategies that help swallowing, easi- When possible, a CSE should also include mealtime obser- est and most difficult food consistencies to swallow), and vation. This is particularly useful in patients with cognitive factors that might influence management (e.g. comorbidi- impairments where feeding and swallowing difficulties may ties, cognition, food restrictions and nutritional status, pres- be influenced by fluctuating levels of attention, fatigue, or ence of gastroesophageal reflux, and cultural preferences) environmental factors (e.g. background noise or other distrac- [30]. Common examples of the many available measures tors). Observations such as the patient’s ability to self-feed, used while compiling a case history are the Functional Oral the need to use adaptive eating utensils, duration of the meal, Intake Scale (FOIS; [78]) and the Mini-Mental State Exami- and the presence of fatigue are noted. Examples of available nation (MMSE; [79]) or Mini-Cog [80] to screen for cogni- standardized CSEs based on mealtime observation are the tive impairment. McGill Ingestive Skills Assessment (MISA [91]) for older After compiling the case history, the clinician forms a persons with feeding difficulties, and the Dysphagia Disorder preliminary clinical hypothesis that is tested during ensuing Survey (DDS; [92]) developed and validated for persons with assessment. Only a few standardized CSE tests are avail- developmental disabilities. Both measures have demonstrated able across dysphagia populations. The Mann Assessment of promising, robust psychometric properties [91, 93, 94]. Swallowing Ability (MASA [81]) is an example of a stand- During the CSE, individualized trials are conducted to ardized CSE. The MASA was validated on stroke patients investigate the effectiveness of compensatory strategies the and has adaptations for patients with head and neck cancer person may already have put in place or to test new strategies (MASA -C [82]). While conducting a CSE, the clinician and examine which are most effective for safe and efficient also completes a clinical observation of the patient noting oral intake. Compensatory strategies comprise changing body posture, head posture at rest, level of alertness, and what the person eats (i.e. diet modification) and changing ability to follow assessment instructions, upper respiratory how the person eats (e.g. head posture, alternate liquid/solid tract secretions, and the patient’s ability to manage his/her swallows, volume control). The efficacy of implementing saliva. In addition, an orofacial examination is conducted adaptive equipment (e.g. beakers, modified spoons, straws) that includes a cranial nerve examination. Oral health may in promoting safe oral intake should also be examined. be assessed using a measure such as the Oral Health Assess- Ancillary to conducting CSE is evaluation such as pulse ment Tool (OHAT [83]). oximetry and cervical auscultation. Pulse oximetry meas- Trial feeding is only considered an appropriate manage- ures peripheral capillary oxyhemoglobin saturation and is ment strategy if the patient has an adequate voluntary cough used to detect a decrease in saturation, which is indicative and is able to manage his/her own secretions. If, however, of aspiration during swallowing [95]. Cervical auscultation the patient is drowsy, medically unstable, and unable to is hypothesized to differentiate between normal and abnor- swallow saliva requiring suctioning, then trial feeding is mal swallowing by listening to the sound of swallowing and deemed too high risk and should not be attempted. Self- swallowing-related respiration using a stethoscope placed feeding is preferred over feeding by carers or health care on the neck [96]. However, there is contention regarding providers, to mimic typical eating and drinking patterns. As diagnostic accuracy of pulse oximetry in predicting aspi- mentioned earlier, there are opposing views regarding which ration and current evidence does not support its use [95]. consistency to trial first. Some clinicians prefer to begin Cervical auscultation, although commonly used, is equally 13 R. Speyer et al.: White Paper by the European Society for Swallowing Disorders Table 4  Psychometric domains and properties according to the COSMIN taxonomy Domain Measurement property Definitiona Validity Degree to which an instrument measures the construct(s) it purports to measure Content validity Degree to which the content of an instrument is an adequate reflection of the con- struct to be measured Structural validity Degree to which the scores of an instrument are an adequate reflection of the dimen- sionality of the construct to be measured Hypotheses testing for construct validity Degree to which the scores of an instrument are consistent with hypotheses based on the assumption that an instrument validly measures the construct to be measured Cross-cultural validity Degree to which the performance of the items on a translated or culturally adapted instrument are an adequate reflection of the performance of the items of the origi- nal version of the instrument Criterion validity Degree to which the scores of an instrument are an adequate reflection of a ‘gold standard’ Reliability Degree to which the measurement is free from measurement error Internal consistency Degree of the inter-relatedness among the items Reliability Proportion of the total variance in the measurements which is because of ‘true’ dif- (intra-rater, inter-rater, test–retest) ferences among patients Measurement error (intra-rater, inter- Systematic and random error of a patient’s score that is not attributed to true changes rater, test–retest) in the construct to be measured Responsiveness Ability of an instrument to detect change over time in the construct to be measured Interpretabilityb Degree to which one can assign qualitative meaning to an instrument’s quantitative scores or change in scores a Definitions derived from Mokkink, Prinsen [24] b Interpretability is considered an important characteristic of a measurement instrument but is not a psychometric property contentious and there is limited evidence to support its use The COSMIN group established an international consen- [96]. sus-based taxonomy, terminology, and definitions of measure- Limitations of the CSE are that protocols vary and that ment properties for health-related patient-reported outcome there is variability in practice even within the same clini- measures [25]: guidelines for using the taxonomy, includ- cal settings and between populations [97–99]. However, its ing a standardized appraisal tool for rating methodological key strength is providing low-cost clinical information to quality of psychometric studies [100], criteria for evaluating the multidisciplinary team in the immediate management of psychometric quality of assessments [101, 102], and a rating patients with dysphagia, especially if clinical teams do not system for synthesizing and grading psychometric evidence have access to instrumental assessments. [101, 102]. The taxonomy distinguishes nine psychometric properties across three domains (Table 4): validity (content Challenges and Minimum Requirements validity, structural validity, cross-cultural validity, hypothesis for Assessment testing for construct validity and criterion validity), reliabil- ity (internal consistency, reliability and measurement error), A core outcome set (COS) is an agreed minimum set of out- and responsiveness. When selecting an assessment, all nine comes that should be measured and reported in clinical trials psychometric properties are considered when identifying the of a specific disease or target population [10]. When selecting assessments with the most robust psychometric properties. outcome measures as part of a COS, four criteria need to be Assessments that have poor psychometric properties considered [10]. First, both the construct to be measured (e.g. should not be used in either clinical settings or research. FHS, HR-QoL) as well as the target population (e.g. age, diag- Minimum requirements for including an outcome meas- nosis) must be clearly defined. Second, existing measures must ure in a COS are high-quality evidence for good content be identified by, for example, performing literature searches validity and good internal consistency [10]. However, as or using recent systematic reviews. Third, the quality of all recent psychometric reviews have identified missing or measures must be evaluated both in terms of quality of psy- indeterminate evidence for many psychometric properties chometric properties as well as feasibility for administering the of existing assessments in dysphagia (e.g. [29, 36, 37]), measure within particular setting. Fourth, one measure must often only preliminary conclusions on the psychometric be selected for each outcome or construct in a COS (Fig. 1). robustness of the assessments can be drawn based on cur- rent available psychometric evidence in the literature. 13 R. Speyer et al.: White Paper by the European Society for Swallowing Disorders Content validity, the degree to which the content of an and remote areas [105], to increase service reach, reduce assessment is an adequate reflection of the construct to be costs [106], and more recently to continue providing safe measured, is considered the most important psychometric health services during the COVID-19 pandemic. property within the COSMIN taxonomy [102]. Concerns around content validity are raised when assessments that have been developed and validated for specific target popu- Recommendations and Future Research lations are used in different populations. For example, the MD Anderson Dysphagia Inventory (MDADI) is a dyspha- Selection of Screening and Assessments gia-specific quality of life questionnaire targeting patients with head and neck cancer [49], whereas the Dysphagia in Where access to instrumental assessment is restricted, the MUltiple Sclerosis questionnaire (DYMUS) is a FHS self- use of clinical assessments becomes exponentially impor- report assessment for adults with multiple sclerosis [103]. tant when evaluating patients’ illness trajectories. There are Assessments like the MDADI and DYMUS that have been many screening and non-instrumental assessments available developed and validated for a specific clinical population for evaluating dysphagia in adults (see Table 5). However, cannot be used in another population without the risk of even though measures may be part of daily clinical practice, compromising its content validity [102]. For an assess- their use may not be warranted due to poor diagnostic per- ment to have good content validity [102], all items need formance or lacking robust psychometric properties. to be aligned with the construct of interest in a specific Therefore, based on this ESSD white paper, the following population and context of use (relevance), all key con- recommendations are made (Fig. 1): cepts of the construct need to be covered (comprehensive- ness), and instructions, items and response options need 1. Discontinue the use of non-validated dysphagia screen- to be understandable to the target population as intended ing tools. Instead, use screening tools with good diag- (comprehensibility). nostic performance, good reliability and validity and Problems may also occur when using a translated version tools that meet feasibility criteria. of an original assessment, without undertaking the required 2. Implement screening using tools that have optimal diag- steps to ensure good cultural validity. The proposed frame- nostic performance in selected populations that are at work of translation by Koller, Kantzer [104] is based on a risk of dysphagia. These populations include, but are not review of influential translation guidelines and summarizes limited to, stroke patients, frail older persons, patients the reconciliation processes that needs to be undertaken with progressive neurological diseases (e.g. Parkinson’s when translating measures. The framework stipulates that disease or dementia), persons with cerebral palsy, and through a process of reconciliation, two or more independ- patients with head and neck cancer. ent forward translations are merged into one single transla- 3. Discontinue the use of measures with insufficient or tion using decision criteria on comprehensibility, cultural poor psychometric properties. Instead, use measures that appropriateness, grammar, and use of relevant and consist- demonstrate robust psychometric properties that meet ent terminology. Next, cross-cultural validity needs to be psychometric quality and feasibility criteria. determined by comparing the performance of items from a 4. Provide quality training in dysphagia screening and translated or culturally adapted assessment with the original assessment to all clinicians involved in the care and assessment version [24]. management of persons with dysphagia. Finally, aspects of feasibility need to be taken into con- sideration when deciding on which assessments to select Future Research and Clinical Practice for measuring outcomes. Feasibility refers to the practica- bility of using an assessment in its intended setting, taking There are great challenges for future research in the screen- into account constraints of time, money, and interpretability ing and assessment of dysphagia in adults: [10]. Other important factors related to feasibility include, for example, patient’s cognitive functioning and physi- 1. Existing measures in dysphagia with incomplete or miss- cal ability, patient’s and clinician’s ability to comprehend ing evaluations of psychometric properties (i.e. validity, items, ease of administration, duration of administering the reliability, and responsiveness), need urgent and ongoing assessment, simplicity of score calculation, accessibility of study. required equipment in different settings, copyright require- 2. New measures need to be developed by using contempo- ments, and associated costs to acquire and administer the rary psychometric standards and methods, such as item assessments [10]. Another consideration include administer- response theory in combination to classic test theory. ing, where appropriate, assessments via telehealth instead of 3. To ensure adequate content validity, studies should be face-to-face to increase accessibility to healthcare in rural conducted at the onset of developing a new measure to 13 R. Speyer et al.: White Paper by the European Society for Swallowing Disorders Table 5  Examples of commonly used screens and assessments for dysphagia in adults Domain Screening and ­assessmenta Acronym Respondent Reference Standardized screening At risk of swallowing problems Gugging Swallowing Screen GUSS Clinician Trapl et al., 2007 Toronto Bedside Swallowing Screening Test TOR-BSST Clinician Martino et al., 2009 Volume-viscosity swallowing test V-VST Clinician Clavé et al., 2008 Standardized assessments Cognition & Communication Mini-Cog – Clinician Borson, 2000 Mini-Mental State Examination MMSE Clinician Folstein et al., 1975 Oral intake status Functional Oral Intake Scale FOIS Clinician Crary et al., 2005 Dysphagia-related quality of life & Dysphagia Handicap Index DHI Patient Silbergleit et al., 2012 Functional health status MD Anderson Dysphagia Inventory MDADI Patient Chen et al., 2001 Sydney Swallow Questionnaire SSQ Patient Dwivedi et al., 2010 Swallowing Quality of Life questionnaire SWAL-QOL Patient McHorney et al., 2002 Oral health status Oral Health Assessment Tool OHAT Clinician Chalmers et al., 2005 Oral Health Impact Profile OHIP Patient Slade et al., 1994 Oral Health Questionnaire for Adults – Patient WHO, 2013 Gastroesophageal reflux disease GERD Impact Scale GIS Patient Jones et al., 2007 Reflux Disease Questionnaire RDQ Patient Shaw et al., 2001 Swallowing Mann Assessment of Swallowing Ability MASA Clinician Mann et al., 2002 Mastication Test of Mastication and Swallowing of Solids TOMASS Clinician Huckabee et al., 2018 Mealtime observation McGill Ingestive Skills Assessment MISA Clinician Lambert et al., 2003 Dysphagia Disorder Survey DDS Clinician Sheppard et al., 2014 Non-standardized assessments Anatomy / Cranial nerve integrity Clinical examination of the tongue, hard and soft palate, teeth, gums, oral mucosa, trigeminal (V), facial (VII), glossopharyngeal (IX), vagal (X), and hypoglossal (XII) cranial nerves. Oral motor skills / Physiology Clinical examination of oral muscle strength, range, tone, steadiness, accuracy and coordination. Mealtime observation including observation of drooling or sialorrhea, mastication, eating speed, cough or choking, oral residue, head and body positioning. Trial feeding Bolus modification, postural adjustments and/or swallow manoeuvers Intervention trials / Compensatory strategies a No international consensus exists on which screen or assessment for dysphagia in adults is preferred. In addition, many screens and assessments have unknown or poor psychometric properties. The presented list of screens and assessments does not provide a comprehensive overview, but examples of common clinical practice. reach consensus on underlying definitions of constructs appropriate method to aim for consensus among experts and to ensure that the items to be include are relevant and stakeholders on the following topics [107, 108]: and comprehensible and the measure is comprehensive a) A universally accepted definition dysphagia? in capturing the underlying construct(s). b) How to define and measure severity of dysphagia? 4. There is a need for robust studies that examine the costs c) What is the minimum set of outcomes (COS) that should and benefits of screening and assessment by telehealth be measured and reported in dysphagia? versus face-to-face administration. d) Which outcome measures should be selected for each 5. There is an urgent need to reach international consensus outcome in the minimum set of outcomes (COS)? on several crucial topics. Delphi studies2 would be an e) What are the critical time points for administering dys- phagia screening and assessment? 2 The Delphi technique is a structured process which aims to develop group consensus on a defined topic through a series of survey rounds Instrument development and international consensus [107]. The same participants complete each round (although some will enhance research designs and outcome measurement individuals may discontinue participating). Rounds are held until consensus is reached (or it becomes apparent that consensus can- in future clinical trials and subsequently lead to improved not be reached). Results from previous rounds are used to inform health care pathways for patients with dysphagia. There is participants about changes that may facilitate consensus in subse- a need for standardized screening and assessment, and con- quent rounds [108]. Using the Delphi technique enables large num- sistency in terminology and definitions used in research and ber of individuals across diverse locations and areas of expertise to be included anonymously, thus avoiding domination of the consensus clinical practice. When addressing the validity, reliability, process by one or a few experts [107]. and responsiveness of outcome measures, both measurement 13 R. Speyer et al.: White Paper by the European Society for Swallowing Disorders properties and criteria for good psychometrics should be 9. Johnston, B.C, et al. Chapter 18: Patient-reported outcomes, defined (e.g. the COSMIN framework). Finally, when refer- in Cochrane handbook for systematic reviews of interventions, J.P.T. Higgins and J. Thomas, Editors. 2019, Cochrane. ring to dysphagia, a common language is needed to define 10. Prinsen CAC, et al. 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Screening accuracy for aspiration using bed- side water swallow tests. Chest. 2016;150(1):148–63. 15. Clavé P, et al. Accuracy of the volume-viscosity swallow test for Conflict of interest The authors declare no potential conflicts of inter- clinical screening of oropharyngeal dysphagia and aspiration. est. Clin Nutr. 2008;27(6):806–15. 16. Baijens LWJ, et al. FEES protocol derived estimates of Research Involving Human and Animal Participants This study does sensitivity: aspiration in dysphagic patients. Dysphagia. not involve human participants or animals. 2014;29(5):583–90. 17. Trapl M, et al. Dysphagia bedside screening for acute- Open Access This article is licensed under a Creative Commons Attri- stroke patients: the Gugging Swallowing Screen. Stroke. bution 4.0 International License, which permits use, sharing, adapta- 2007;38:2948–52. tion, distribution and reproduction in any medium or format, as long 18. Newman R, et al. 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