Objectives:

This report was requested by the Health Care Financing Administration, which sought an evidence-based assessment of methods for diagnosing and treating swallowing disorders (dysphagia) in elderly individuals with neurologic diseases, and specifically those methods associated with the services provided by speech-language pathologists. About 6,228,000 Americans over age 60 have dysphagia, and about 300,000 to 600,000 people are affected by dysphagia resulting from neurologic disorders each year.

This report addresses four questions: (1) How does diagnosis of dysphagia or aspiration affect treatment courses and patient outcomes? (2) What are the indications for diagnosing patients using a full bedside exam (BSE), modified barium swallow, fiberoptic endoscopy, or other instrumented exams? (3) Is one diagnostic technology more effective than any other? and (4) When is noninvasive therapy appropriate, and when should feeding tubes be used in certain patient populations?

Search Strategy:

We used broad-based literature searching to ensure that we found all relevant information. Thus, we searched 23 electronic databases, including MEDLINE and Embase. Search terms included those relevant to the disorder, diagnostics, epidemiology, etiology, and treatment of dysphagia. Search dates depended on the database, but ranged from 1945 to July 1998. We also searched 23 World Wide Web sites, conducted hand searches of article bibliographies, and sought published and unpublished information from experts in the field.

Selection Criteria:

We adopted broad criteria to ensure retrieval of all relevant information. Articles were retrieved if they were clinical studies of any design containing information derived from 10 or more patients. Two researchers independently requested articles. Disputes were resolved in favor of obtaining the article.

Data Collection and Analysis:

Data from clinical trials on diagnostic test performance and/or patient outcomes were entered directly into evidence tables. This information included study size, design, diagnostic method(s), patient selection criteria and characteristics, and patient outcomes.

Studies were separated by their design, but their quality was not necessarily ranked according to it. We did not rigidly adhere to a formal quality ranking scheme because some randomized controlled trials (RCTs) had flaws serious enough to render their results unreliable. Similarly, we did not always consider case-controlled studies to provide more reliable information than case series because of certain flaws in the former.

To reach our conclusions, we performed two cost-effective analyses, a meta-analysis of the efficacy of the 3-ounce water test, a similar meta-analysis of the BSE, an exploratory meta-analysis (so called because the control data were derived from historical sources) on the effects of dysphagia diagnosis and treatment programs on patient outcomes, an illustrative meta-analysis that addresses the technical issue of the low statistical power of vote-counting procedures, and numerous other quantitative analyses. The need to perform these original calculations is a reflection on the relatively poor reporting in this literature.

Main Results:

We focused on dysphagia diagnosis and treatment programs because assessment of dysphagia diagnosis and treatment independent of one another provides only limited information. The emphasis of our analysis was on stroke victims, which reflects the preponderance of the literature. Stroke victims also comprise the largest group of patients with neurologic disease who have dysphagia. Outcomes of particular interest were aspiration pneumonia, malnutrition, dehydration, and quality of life (QOL), but the most data were available for aspiration pneumonia.

The evidence regarding the first question, which is the most significant of our key questions, suggests that dramatic reductions in the occurrence of pneumonia are observed when a systematic program of diagnosis and treatment of dysphagia in an acute stroke management plan is implemented. Because these data are from historically controlled studies rather than RCTs (which may be unethical in this context), the exact magnitude of this reduction in pneumonia rates is difficult to determine. Also for this reason, it is equally difficult to determine the contribution of the dysphagia-specific aspects of the management programs to these rate reductions (as opposed to those aspects of the stroke management program not related to diagnosis and treatment of dysphagia). However, because the effects observed in these studies are substantial, it would be imprudent to ignore them. Therefore, these results must be taken as evidence of efficacy of these programs. Malnutrition, dehydration, and QOL were not addressed in available studies.

Regarding the second question, the risk for developing aspiration pneumonia cannot be accurately predicted from any single clinical sign or symptom. There is a clear-cut need to optimize a brief initial exam that employs several key signs and symptoms to accurately detect patients with possible unsafe swallows and who therefore need more extensive testing.

The results of the studies of diagnostic test performance that address the third question are erroneous because treatment necessarily follows diagnosis of a swallowing disorder. This treatment makes it impossible to distinguish between the true- and false-positive results of these tests. Because of this, the purely diagnostic abilities of the various tests cannot be determined; thus, the tests can only be compared by assessing how they direct treatment and influence adverse patient outcomes, as addressed in our first question above.

We constructed two cost-effectiveness models to address this issue, and their results suggest that use of the full BSE in dysphagia programs reduces costs. These models, which are based on published protocols and findings, assume that patients will receive a preliminary bedside assessment, and that one result of this assessment is that no more than about 39 percent of patients will be referred for further evaluation, as occurred in the best study we evaluated. Under these conditions, our cost-effectiveness analysis suggests that dysphagia diagnosis and treatment programs that employ the full BSE would either save money or have very little net cost if they reduced pneumonia rates by amounts similar to those obtained in certain published studies. In addition, our results indicate that the slightly higher costs of videofluoroscopy would be offset if it provided slightly less than an additional 10 percent reduction in pneumonia rates, again assuming that no more than about 39 percent of patients are referred for videofluoroscopy or the full BSE.

Evidence related to the fourth question consists of limited data from a single RCT concluding that a soft mechanical diet including thickened liquids results in lower morbidity than does a pureed diet. Although numerous other studies have been conducted on dysphagia treatments, their designs make it impossible to assess the efficacy of individual treatments. A single RCT with low statistical power reported inconclusive results about the effect of treatment intensity level on patient outcomes.

A well-designed trial that compares dysphagia management programs using different diagnostic modalities is needed. This trial should take into account the current lack of a demonstrated gold standard diagnostic test, have acceptable statistical power, and consider the fact that treatment of patients distorts measures of diagnostic test performance. Because of this urgent need, we provide a detailed description of the design and analysis of a trial that would answer several major unanswered questions.

Conclusions:

Available evidence on the diagnosis and treatment of dysphagia is extremely limited. Nevertheless, current data suggest that implementation of dysphagia management programs for stroke patients in the acute-care setting is accompanied by a reduction in pneumonia rates. Use of the full BSE in these programs appears to be cost-effective. The limitations of available evidence do not allow us to determine the extent to which videofluoroscopy or fiberoptic endoscopy reduce pneumonia rates compared with the full BSE despite the fact that it is reasonable to believe the additional information they provide would lead to improved patient outcomes. Although the added benefits provided by instrumented exams are likely to be small, videofluoroscopy may be cost-effective if used in programs in which no more than about 39 percent of all patients are referred to this test, and if its use leads to an additional 10 percent reduction in pneumonia rates, compared with the full BSE. There is a clear-cut need to optimize a brief initial exam that accurately detects patients with possible unsafe swallows who may therefore need more extensive testing. Study designs used in the evaluation of noninvasive therapy have made it impossible to assess the efficacy of individual treatments. However, there is evidence supporting the use of a soft mechanical diet over a pureed diet for preventing aspiration pneumonia in stroke patients with dysphagia who have a history of aspiration pneumonia. The evidence on whether treatment that is more intensive yields better patient outcomes than less intensive treatments is inconclusive. Well-designed studies, particularly those that compare diagnostic modalities, are needed.