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CADTH Health Technology Review
Authors; Robyn Haas, and Sharon Bailey.
Dysphagia, or difficulty swallowing, is a common complication of many conditions.1 People who experience dysphagia have difficulty moving food or liquid, including saliva, from their mouth into their throat and esophagus.1,2 Swallowing is a process that takes place in 3 phases: the oral preparatory phase, the pharyngeal phase, and the esophageal phase.1,2 Dysphagia occurs when there is an issue with neural control or structural problems in any part of this swallowing process.1,2 There are numerous factors that may cause this to happen, including, but not limited to, prolonged intubation, dementia, stroke, Parkinson disease, congenital conditions, head and neck cancer, and others.1
There are 2 primary methods that health care practitioners, particularly speech-language pathologists (SLPs), use to assess and help diagnose dysphagia: a clinical and/or bedside assessment or an instrumental assessment.3
The most widely used instrumental assessment is a videofluoroscopic swallowing study (VFSS).3 This may also be referred to as videofluoroscopy, or a modified barium swallow study (MBSS). A VFSS is a recorded X-ray exam of the swallowing process where the patient consumes foods or liquids in addition to barium to improve visibility.2 The images from the recording can then help identify if and where in the swallowing process issues occur.2 Another commonly used instrumental assessment for dysphagia is fibreoptic endoscopic evaluation of swallowing (FEES).2 During a FEES procedure, the SLP inserts a lighted, flexible endoscope through the nose and into the mouth and throat.2 This allows the SLP to examine the physical structures involved in swallowing as well as how a person’s swallowing mechanism responds to different stimuli (e.g., food, liquids).2
A clinical or bedside swallowing assessment can be performed without any special equipment. To check for signs of dysphagia or aspiration during the assessment, the SLP will typically ask questions about the patient’s symptoms and medical history and evaluate the structures involved in swallowing (e.g., teeth, lips, jaw, tongue, cheeks, and soft palate).2,4 The SLP may also ask the patient to cough or clear their throat, and check reflexes such as gagging. Finally, the SLP may ask patients to swallow liquids and foods that vary in thickness and consistency, and note any issues around chewing, swallowing, and breathing, as well as listen to vocal quality for signs of aspiration.2,4
Instrumental swallowing assessments for dysphagia such as VFSS and FEES are more accurate and comprehensive; however, they also require more financial, time, physical, and human resources. This is especially true for VFSS, which requires medical imaging staff, whereas FEES does not. VFSS also exposes individuals to radiation. As such, conducting clinical swallowing assessments instead of instrumental swallowing assessments might be an option to help reduce a strain on resources. By conducting this review, we can explore the available evidence to determine how instrumental and clinical swallowing assessments compare to each other.
The purpose of this report is to summarize and critically appraise the evidence from medical databases and grey literature about the diagnostic accuracy and clinical utility of instrumental swallowing assessments versus clinical evaluation for people with suspected dysphagia. Comparing different types of instrumental assessments to each other was not in scope for this review. We also aimed to identify evidence-based guidelines about the use of instrumental and clinical assessments for suspected dysphagia.
An information specialist conducted a literature search on key resources, including MEDLINE, Embase, the Cochrane Database of Systematic Reviews, the International HTA Database, and the websites of Canadian and major international health technology agencies, as well as a focused internet search. The search approach was customized to retrieve a limited set of results, balancing comprehensiveness with relevancy. The search strategy comprised both controlled vocabulary, such as the National Library of Medicine’s MeSH (Medical Subject Headings), and keywords. Search concepts were developed based on the elements of the research questions and selection criteria. The main search concepts were instrumental swallowing assessments and dysphagia. CADTH-developed search filters were applied to limit retrieval to health technology assessments, systematic reviews, meta-analyses, indirect treatment comparisons, any types of clinical trials or observational studies, and guidelines. The search was completed on November 30, 2023, and limited to English-language documents published since January 1, 2019.
One reviewer screened citations and selected studies. In the first level of screening, titles and abstracts were reviewed and potentially relevant articles were retrieved and assessed for inclusion. The final selection of full-text articles was based on the inclusion criteria presented in Table 1.
Selection Criteria.
We excluded articles if they did not meet the selection criteria outlined in Table 1, if they were duplicate publications, or if they were published before 2019. We also excluded guidelines with unclear methodologies.
One reviewer critically appraised the included publications using the following tools as a guide: the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) checklist5 for diagnostic test accuracy (DTA) studies and the Appraisal of Guidelines for Research and Evaluation (AGREE) II instrument6 for guidelines. We did not calculate summary scores for the included studies; rather, we described the strengths and limitations of each included publication narratively.
This report includes 4 nonrandomized studies and 6 evidence-based guidelines. The study selection details are presented in Appendix 1. Additional references of potential interest are provided in Appendix 5.
The detailed characteristics of the included publications are provided in Appendix 2.
We included 4 cross-sectional studies that examined the DTA of various clinical or bedside screening evaluations compared to instrumental assessments for dysphagia.7-10 These studies were conducted in Turkey,7 the US,10 Brazil,9 and South Africa.8 The studies included a total of 233 individuals. Two of these studies included adults, 40 of whom had previously had an ischemic stroke7 and 31 of whom had a diagnosis of Parkinson disease.9 The other 2 studies8,10 included neonates or infants, 1 of which was a retrospective chart review.
All of these studies used instrumental assessments as reference standards and did not include any instrumental assessments as index tests. One study examined multiple index tests,7 including the bedside water swallow test (BWST), the modified Mann Assessment of Swallowing Ability (mMASA), saturation, and the National Institutes of Health Stroke Scale (NIHSS), all of which are clinical assessments. This study used FEES as the reference standard.7 The index test for another study was the Swallowing Clinical Assessment Score in Parkinson Disease (SCAS-PD) and the reference standard used was the videofluoroscopic swallowing study (VFSS).9 Both studies that examined dysphagia in neonates or infants used the MBSS as the reference standard.8,10 One of these studies10 used clinical feeding evaluation (CFE) as an index test and the other8 used the neonatal feeding assessment scale (NFAS).
The outcomes relevant to this research question included sensitivity and specificity (4 studies)7-10 and positive predictive value and negative predictive value (3 studies).7,8,10
We did not identify any evidence about the clinical utility (e.g., reported health benefits, quality of life, or safety) of instrumental swallowing assessments versus clinical evaluation that met the inclusion criteria for this report.
We included 6 evidence-based guidelines with recommendations that were developed from systematic searches for relevant evidence. These guidelines were developed by groups in Korea,11 the US,12 Japan,4 and Portugal.13 Additionally, 2 guidelines were developed by multinational groups.14,15 The target populations include individuals who have had a stroke and have suspected dysphagia (2 guidelines),13,15 individuals with Parkinson disease (1 guideline),14 individuals living with swallowing dysfunction (1 guideline),12 and individuals who have a symptom or diagnosis of oropharyngeal dysphagia (1 guideline).11 One guideline does not explicitly state the target population but we can infer based on the contents that it intends to target individuals with oropharyngeal dysphagia.4 The intended users of these guidelines include various health care professionals (e.g., nurses, SLPs, physicians) involved in the treatment of patients with dysphagia.4,11,13,15 Two guidelines do not specifically describe the intended users, though we can infer that the recommendations would be useful for health professionals who work with individuals who are suspected to have dysphagia.12,14 All of the guidelines provide recommendations about the use of clinical evaluation and instrumental assessments (including VFSS and FEES) for dysphagia.4,11-15 All of the guidelines consider the effectiveness of assessment tools (clinical and instrumental) in diagnosing individuals with dysphagia when formulating recommendations relevant to this report.4,11-15
Additional details regarding the strengths and limitations of the included publications are provided in Appendix 3.
The population in all 4 DTA studies7-10 on instrumental assessment versus clinical evaluation of dysphagia matched the population of interest in this report (i.e., individuals suspected of having dysphagia). Three studies8-10 used appropriate methods for patient selection, while 1 study7 did not clearly report a detailed account of patient sampling methods. In all 4 studies,7-10 the choice of index tests and reference standards for dysphagia matched those targeted by this review. Additionally, all patients received the reference standard and all studies used reference standards likely to correctly classify dysphagia. The index test results were interpreted without the knowledge of the results of the reference standard in 2 studies,7,9 which reduced the potential for bias due to prior knowledge when interpreting the index test results. It was unclear if this was the case in 2 other studies.8,10 The reference standard results were interpreted without knowledge of the results of the index test in 2 studies.7,8 It was unclear if this was the case in the other 2 studies.9,10 In 3 studies, the index tests and reference standards were conducted within an appropriate time frame (i.e., within days of each other). One study conducted the index test and reference standard at the same time,9 and 2 others conducted the index tests and reference standards within 7 days of each other.8,10 The timing of these tests reduced the likelihood of misclassification due to the timing of the tests.8-10 The fourth study did not report the timing of test administration.7 There were missing results for both instrumental assessment and clinical evaluation for 3 individuals from the recruited population in 1 of the studies.9 The reasons for this missing data were not presented and so it is unclear whether this could have introduced bias into the study. The authors of all 4 studies declared that they had no conflicts of interest;7-10 however, the funding source was not clearly reported in 2 of the studies.8,10 One of the studies appears to use the terms screening and diagnosis to refer to the same thing. This may lead to confusion around the intent of the assessments. However, based on the overall context of the rest of the study, it appears to be relevant to this review.
All guidelines4,11-15 state their scope and objective, and all guidelines except for Dhar et al.(2023)12 specifically describe the health questions covered.4,11,13-15 All guidelines except for Sugama et al.(2022)4 describe the population to whom the guidelines are meant to apply;11-15 however, based on the content of the guideline, we inferred that the target population is individuals with suspected or confirmed oropharyngeal dysphagia.
All guidelines included individuals from relevant professional groups during the guideline development process.4,11-15 These professional groups included SLPs, nurses, specialist physicians (e.g., gastroenterologists, neurologists, geriatricians), and allied health professionals (e.g., occupational therapists). Three guidelines note that they do not include the views and preferences of the target population.13-15 Three other guidelines do not report whether they obtained this information.4,11,12 As a result, it is unclear if the recommendations and information provided in the guidelines align with the experiences of individuals with lived experience. Four4,11,13,15 of the guidelines clearly define their target users. Cosentino et al.(2021)14 do not explicitly state their target users but refer to “individuals in the neurological health care practice” as a relevant population. Dhar et al. do not clearly define their target users.12
All guidelines used systematic methods to search for evidence, clearly describe the criteria for selecting evidence, and clearly describe the methods for formulating their recommendations.4,11-15 This rigorous development helps improve the reproducibility of the guidelines. All the guidelines also considered the health benefits, side effects, and risks in formulation recommendations, and describe the strength and limitations of the body of evidence, often using existing critical appraisal tools such as Grading of Recommendations, Assessment, Development, and Evaluations (GRADE), Appraisal of Guidelines for Research and Evaluation II (AGREE II), A MeaSurement Tool to Assess systematic Reviews (AMSTAR 2), and Critical Appraisal Skills Programme (CASP) to evaluate the included literature.4,11-15 Five of the guidelines4,11,13-15 provide an explicit link between the recommendations and the supporting evidence. The guideline by Dhar et al. provides supporting evidence within the guideline; however, its presentation does not clearly connect the evidence to its corresponding recommendation.12
The guidelines published by Sugama et al. and Dziewas et al.(2021) were externally reviewed by experts before their publication.4,15 The other 4 guidelines do not report whether their guidelines were externally reviewed.11-14 Yang et al.(2023), Dziewas et al. and Oliveira et al.(2021) provide a time frame for which their guidelines will be updated (e.g., every 5 years, in the year 2024).11,13,15 Cosentino et al., Sugama et al., and Dhar et al. do not provide a procedure for updating their guidelines.4,12,14 The key recommendations in all guidelines are easily identifiable and include different options for assessing, diagnosing, managing, and treating dysphagia.4,11-15
Yang et al. note that they considered obstacles and facilitating factors when developing and grading their recommendations but do not elaborate on these considerations.11 Sugama et al. include facilitating factors among their recommendations but do not discuss barriers.4 Conversely, Dziewas et al. discuss potential barriers to application but not facilitators.15 Oliveira et al. note that the specific context in which the guidelines are implemented will determine the facilitators and barriers to their implementation but do not provide examples or describe what the nature of the barriers and facilitators might be.13 Cosentino et al. and Dhar et al. do not describe facilitators or barriers to guideline application.12,14 Yang et al. note that they considered resources and costs when developing and grading their recommendations but do not provide further details on resource and cost considerations.11 Sugama et al. include cost considerations in some, but not all, of their recommendations.4 The other 4 guidelines do not discuss the potential resource implications of applying the guidelines.12-15 None of the guidelines provide tools or advice on how to implement the recommendations, nor do they present monitoring or auditing criteria.4,11-15
Five guidelines declare potential conflicts of interest of the guideline development group members, none of which are relevant to the development of the guidelines.4,11,13-15 Yang et al. explicitly state that the development of their guideline was not influenced by any funding group.11 Both Oliveira et al. and Dziewas et al. state that the authors did not receive financial support for the preparation of their guidelines.13,15 Cosentino et al. and Sugama et al. both provide information about their respective funding sources but do not report whether these influenced the guideline development.4,14 Dhar et al. do not provide information on conflicts of interest or funding sources.12
Appendix 4 presents the main study findings, detailed recommendations, and supporting evidence relevant to this report.
We identified 4 cross-sectional studies7-10 about the DTA of instrumental swallowing assessments versus clinical evaluation in individuals with suspected dysphagia. Three studies used VFSS or MBSS,8-10 2 terms used to refer to the same study, as a reference standard and 1 study used FEES,7 all of which are relevant to this report.
In individuals who have previously had a stroke, when compared to FEES, BWST had:7
In individuals who have previously had a stroke, when compared to FEES, mMASA had:7
In individuals who have previously had a stroke, when compared to FEES, saturation had:7
In individuals who have previously had a stroke, when compared to FEES, BWST plus mMASA had:7
In individuals who have previously had a stroke, when compared to FEES, saturation plus mMASA had:7
In infants, when compared to MBSS, CFE had:10
In infants, when compared to MBSS, CFE had:10
In individuals with Parkinson disease, when compared to VFSS, SCAS-PD9 had:
In neonates, when compared to MBSs, NFAS8 had:
We did not find any evidence on the clinical utility of instrumental swallowing assessments versus clinical evaluation for patients with suspected dysphagia; therefore, we cannot form conclusions on this research question.
All the DTA studies7-10 examined a different type of clinical swallowing assessment. They also used different reference standards.7-10 As such, we are unable to examine how test accuracy compares across different studies and if there is consistency between studies. Additionally, the DTA studies were conducted in a range of populations. Two of these studies7,9 focused on patients with specific conditions associated with dysphagia (i.e., Parkinson disease and stroke). Consequently, the results of each of these studies are only applicable to people who also have these respective conditions and cannot necessarily apply to other populations (e.g., older adults who have not had a stroke). As well, because only 1 of the DTA studies10 reported 95% CIs, we cannot determine the precision of the reported sensitivities, specificities, negative predictive values, or positive predictive values.
In terms of the evidence-based guidelines, only 1 recommendation11 specifically recommends the use of instrumental assessments over clinical evaluations. While some of the guidelines do indicate that preference should be given to instrumental assessments when resources are available, most of the other recommendations discuss using the tests in combination or in sequence. Additional details or guidance about which contexts and populations would best benefit from the use of instrumental assessments or clinical evaluations would be useful. Similar to the DTA studies, the target population of the included guidelines varies, with some specifically intended for people with Parkinson disease, others intended for people who have had a stroke, and others for a more general population. As a result, the recommendations in some of the guidelines may not necessarily apply to all patient groups. Furthermore, several of the included recommendations are based on low-quality to moderate-quality evidence, which may limit their applicability. Four of the included guidelines also do not report on whether they underwent external review before publication, which may affect the suitability of the guidelines for their intended purpose.
Finally, none of the included DTA studies or evidence-based guidelines were conducted or developed in Canada, which may limit the generalizability of the findings of this report to the Canadian health care context.
This report includes 4 cross-sectional studies7-10 about the DTA of instrumental swallowing assessments versus clinical evaluation for individuals with suspected dysphagia. It also includes 6 evidence-based guidelines4,11-15 about instrumental and clinical evaluation for suspected dysphagia. Based on the literature search conducted for this review, we did not identify any evidence about clinical utility that met our inclusion criteria. As such, we cannot make conclusions about health benefits, quality of life, or safety outcomes related to instrumental or clinical assessments for dysphagia.
The DTA studies examined a range of index tests that varied considerably in their sensitivities and specificities.7-10 Across all the index tests studied, sensitivities ranged from low to very high (41.1% to 100%) and specificities ranged from very low to high (15.3% to 88.2%). The authors of 3 of the DTA studies7-9 concluded that the clinical evaluations they examined could feasibly be used to diagnose dysphagia when resources are limited. One of these studies investigated multiple index tests and while they stated that, generally, the tests they examined may be useful, they did note that 1 of tests (BWST plus mMASA) yielded the best results. The fourth DTA study10 determined that more research was required for the index tests they examined (i.e., CFE). However, these findings may not be generalizable to all individuals with dysphagia because the studies used relatively small sample sizes and specific populations, including neonates and infants, people with Parkinson disease, and people who had experienced stroke.
Overall, the evidence-based guidelines were rigorous and clear in their methodologies and reporting. The relevant recommendations were based on evidence that ranged from low to high quality; however, most fell into the low and moderate categories. Based on the recommendations, instrumental swallowing assessments such as VFSS and FEES appear to be the first choice for dysphagia assessment. While clinical evaluation was recommended, it was often done so in association with instrumental swallowing assessments (e.g., clinical evaluation should be followed by instrumental assessment).
Based on the findings of both the DTA studies and evidence-based guidelines, it appears that while clinical evaluation may not be a perfect replacement for instrumental swallowing assessments, they may be effective standalone tools for diagnosing dysphagia in settings where resources are limited. However, this is dependent on the population involved and the type of clinical evaluation used. Additional high-quality DTA studies that examine the same types of clinical feeding evaluations would help strengthen the evidence about whether they can be used as standalone assessments when the resources for instrumental swallowing assessments are not available. Furthermore, high-quality studies about the clinical utility of instrumental swallowing assessments versus clinical evaluation are needed to inform us about if and how these 2 approaches may differentially affect the health benefits, safety, and quality of life in individuals with suspected dysphagia. Finally, because some of the included guidelines recommend following clinical assessments with instrumental assessments, future research examining the potential benefits, harms, and costs of a sequential approach to dysphagia assessment may be useful.
bedside water swallow test
clinical feeding evaluation
diagnostic test accuracy
fiberoptic endoscopic evaluation of swallowing
modified barium swallow study
modified Mann Assessment of Swallowing Ability
neonatal feeding assessment scale
Swallowing Clinical Assessment Score in Parkinson’s Disease
speech-language pathologist
videofluoroscopic swallowing study
Contributor: Chris Kamel
Selection of Included Studies.
Characteristics of Included Primary Clinical Studies.
Characteristics of Included Guidelines.
Note that this appendix has not been copy-edited.
Strengths and Limitations of Diagnostic Test Accuracy Studies Using the QUADAS-2 Checklist.
Strengths and Limitations of Guidelines Using AGREE II.
Note that this appendix has not been copy-edited.
Summary of Findings by Outcome — DTA of Clinical or Bedside Swallow Examination.
Summary of Recommendations in Included Guidelines.
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