Posted by Title: The Dysphagia Outcome Severity Scale
Authors: O’Neil, Purdy, Falk, & Gallo
Journal: Dysphagia
Year of Publication: 1999
Purpose: “The purpose of this study was to develop an easily administered, 7-level functional scale that assigned severity with acceptable reliability based on results of the MBS procedure and allowed improved consistency in recommendations for nutrition level, diet, and independence.”
Population: 135 consecutive patients across 3-month period for MBSs at large teaching hospital (mix of acute, outpatients, acute rehab patients)
This review will give you all the truth behind the DOSS if you dare to add it to your dysphagia repertoire! The original article is not only an easy-to-read but also easy-to-implement call to action. And because everyone’s toolbox might look a little different where you’re at, it can be worth knowing what might be beneficial to add or dig back out in yours!🤓
- Only got a sec?
- The DOSS can be used as a clinically comprehensive and consistent measure to quantify dysphagia severity based off VFSS results and interpretation
- Only got a minute?
- “The scale was not intended to determine reliability of the MBS procedure itself..It was intended, however, to improve consistency of documentation and recommendations across clinicians and within individual clinicians, provide a basis for comparing patients with each other and over time, and to introduce a possible measure of functional outcomes in dysphagia“
- “the DOSS was proven to have excellent interrater (90%) and intrarater (93%) reliabilities congruent with that of the internationally recognized FIM“
- “The present results indicate that the DOSS can be used by trained clinicians to better describe severity level of dysphagia with excellent reliability and to make more consistent recommendations for nutrition, diet, and independence“
- Got more time? Keep Reading!!
Let’s may sure we don’t get too ahead of ourselves in hoping for a miraculous unicorn measure, especially given the amazing foundation MBSImP has provided since its 2005 creation along with DIGEST‘s offerings. And of course we can’t talk about scales and scoring without mentioning the infamous Penetration-Aspiration Scale (PAS) for quantifying the degree of airway invasion. But it can always be beneficial to know what other options there are, and while we can’t be sure the grass will be greener on the other side, we at least take a peek.😊
The article also agrees that there are also a handful of functional, observational, or patient-reported outcome measures such as the following that report on a variety of different areas from nutritional intake, to symptoms, and overall quality-of-life barriers (this list is definitely not inclusive!):
The authors also give you some background into previous attempts of different severity measures, many of which were described for lacking in things like inter-/intra-rater reliability. This was even recognized early on by Wilcox et al. (1996) stating “instances of high agreement among clinicians were not abundant” when it came to identifying swallowing deficits and generating treatment recommendations from MBSS. Vose et al. (2018) also echoed, “Poor to modest agreement in swallowing impairment identification, frequent false positives, and wide variability in treatment planning recommendations.”
“Existing scales have relied on too general and subjective descriptions per level, have failed to encompass all important dysphagia issues, or have not presented acceptable levels of reliability. Both the Cherney et al. scale and the ASHA scale are 7-point severity scales that assign severity based on nutritional and independence levels but do not associate each level with patients’ dysphagia deficits that can be objectively and consistently measured.” p.7
First Stage of Development:
While many of the above measures can be very helpful guides, their use of actual instrumental swallow studies are all but equal🚫. Recognizing this, the authors weaved all these different ways to quantify and qualify how severe a patient’s dysphagia is currently and across time by first focusing on the following 3 factors (which seemed to turn into a mix of FOIS/FIM/ASHA-like quantifiers):
- Level of Independence
- 7 levels based off FIM model correlating to severity
- (0=total dependent, 7=WNL/Fully Independent)
- Level of Nutrition
- 2 possible nutrition recommendation types, correlating to severity
- (Levels 1-2= Nonoral Nutrition, Levels 3-7=Full Oral Nutrition)
- Diet Level & Diet Modifications
- Level 3 = 2+ diet consistency restrictions
- Level 4 = 1-2 diet consistency restrictions
- Level 5 = May need 1 diet consistency restriction
- Level 6-7 = Normal diet consistency
It’s worth mentioning that the authors did a “retrospective/informal analysis of all MBS reports from a single month” which showed significant variety when it came to documenting “Mild, Moderate, or Severe Dysphagia” within and across clinicians.
“There was also notable inconsistency in the recommendations for supervision, diet consistency, and nutritional level based on the documented MBS findings.” p.2
Take a quick moment to just think what would happen if your hospital/setting completed this type of review (without internally freaking out😱). Is anyone else getting pumped up about the possibility of improving our ability to be more consistent, reliable, and helpful in our fluoro-follow-up recommendations?!? While it’s always scary to think we may not be doing as good as someone else and find others disagree with your thinking, but that’s the only way we’ll ever change and keep moving our field forward!!😉
The authors’ next task was to try to describe swallow impairments in an objective manner. Considering our field is still continuing to try to push the ball forward on this task almost 24 years later, I’d say their heads were in the right direction even back in the ’90s which is always hopeful!
Second Stage of Development:
The authors decided to break things down in a pretty simple way and even channeled some of Logemann’s logic to do so. After reviewing 100 previous MBSS studies, they concluded the differences between who was recommended NPO vs a modified texture diet vs a completely normal texture diet depended on the following:
- Oral Transfer
- “Patients in the present study were clinically judged on the degree of bolus loss or oral retention (after the sallow) and the patient’s ability to compensate with or without cueing“
- Pharyngeal Stage Retention
- “Pharyngeal retention is defined as material that remains in the pharynx (valleculae and/or pyriform sinuses) after a swallow has been completed“
- “considers the patient’s ability to either clear the retention automatically with a re-swallow or clear retained material with a re-swallow when cued“
- Aspiration/Penetration
- “Airway penetration is defined as material that enters the airway into the laryngeal vestibule, above or to the level of the vocal cords. Aspiration is defined as material that goes into the trachea, below the level of the vocal cords“
- “The following factors were considered in determining diet recommendations: the number of consistencies penetrated or aspirated, the presence or absence of a reflexive and/or elicited cough to clear penetration or aspiration, and the level to which the material penetrated into the airway“
“The severity of penetration–aspiration was based on retrospective report analysis and through the general framework proposed by Rosenbek et al. in their study on the penetration–aspiration scale.” p.3
Things to Consider:
Before moving forward, let’s take a step back and really let all this sink in…
First off, what are YOUR thoughts on these “back-to-basic-like” factors?? Do you feel this is making it all too simple🤔? Or do you think the simplification is good to at least have some type of quantification versus just “clinical judgment??”
The second point to consider is the way those 3 impairment categories are being measured, particularly pharyngeal stage retention. While we obviously can’t blame the authors for not being able to travel in the future to the 21st century where we now have more advanced ways to measure pharyngeal residue like Yale Pharyngeal Residue Scale, Normalized Residue Ratio Scale and others, even back then we were likely asking questions to explain how a greater amount of residue left in the pharynx relates to the patient’s ability to safely maintain nutrition (where more severe= unable to clear despite cues), and how “the impact of retention on the severity of dysphagia was based on the relative amount of barium retain in the valleculae/pyriform sinuses (mild, moderate, severe).” Luckily, now we’ve learned how this can easily be misjudged, especially on the 1 dimensional (even 2-dimensional sometimes) views.
Sample Population:
A mix of men (n=78) and women (n=57) from ages 21-95 years (averaging ~73 years) that required an MBS procedure with a variety of diagnoses and levels of severity including:
- Neurological diagnoses
- (stroke, neurosurgery, Parkinson’s, dementia, encephalopathy, TBI, msucular dystrophy, etc.)
- General Medical/Surgical diagnoses
- (GI disorders like bleeds, bowel obstructions, esophagi, etc.)
- Pulmonary related diagnoses
- (pneumonia, COPD, asthma, respiratory failure, pleural effusion, etc.)
- Cardiac related diagnoses
- (myocardial infarction, open heart surgery, congestive heart failure, coronary artery disease, carotid endarterectomy, heart transplant, etc.)
- ENT related diagnoses
- (laryngeal cancer, vocal fold paralysis, polyps)
If that list doesn’t scream “typical caseload in acute hospital setting,” then I don’t know what does!🤪
“The DOSS was used to assign a severity level once the objective assessment had been determined by the speech pathologist and radiologist. The videofluoroscopic swallowing assessments followed hospital protocol adapted from Logemann’s procedures.” p.3
Because we need to remember this was way before IDDSI, after the typical oral motor/cranial nerve examination, a protocol of thin, medium, thick, puree, and solid barium consistencies were administered “as per their ability to swallow.” While unfortunately we didn’t get the specific quantities (tsp versus cup?) or feeding methods (independently fed or SLP?), and because this also way before MBSImP, we’re stuck with either guessing or remembering what we did back in the day😉…
Despite the review of 90’s VHS-taped swallows, the SLPs actually had some back and forth blinding to re-assess severity level for intrajudge rating after 2-4 weeks as well as some initial training for specific instruction and criteria to guide them when rating for the DOSS.
For example, the authors ensured that discriminating factors such as a patient’s environment (amount of supervision realistically available for patient), cognition (ability to learn and use strategies/reliance on supervision etc.), premorbid nutrition, acuity of dysphagia, and current medical status were considered when assessing and rating the overall severity which per the authors, could possibly lead to a “more conservative stance on a patient with multiple current medical concerns.”
Here’s the quick breakdown for what each level of the DOSS resulted in using the above rating criteria across all 135 patients (n=_; _%):
- Functional swallow/normal diet:
- Within functional limits/Modified independent (22; 16%)
- Totally normal in all situations (7; 5%)
- Full oral nutrition but with a restricted diet and level of independence:
- Moderate dysphagia (21; 15.6%)
- Mild to moderate dysphagia (30; 22%)
- Mild dysphagia (28; 21%)
- Nonoral nutrition required:
- Moderately Severe dysphagia (17; 12.6%)
- Severe dysphagia (10; 7%)
Inter-rater Reliability:
“both judges agreed and assigned an exact match for 121 of 135 cases (90%).”
Because the math here is easy enough for even ME to figure out, 13/14 of the differing ratings were only a 1 level difference, and ALL (14/14 differing ratings) were within 2 levels of each other. The fact that we know each and every one of us SLPs has a very different brain and way of thinking, to come that close is an inspiring sign👍! Additionally, “interjudge agreement was good for rating all levels of the scale (82-100%),” with unsurprisingly the “normal/Level 7” being the most consistent agreed upon rating.
Intra-rater Reliability
When the 4 judges re-scored the same videos they were 93% reliable across all videos (10 were different). And of those 10 differing scores from the first to the second time around, 6 of them were only a 1-level difference, with ALL of the total 10 differing scores only 2 levels off.
I gotta admit I was pretty shocked when reading those almost-too-close-to-call results. On the flipside, the authors quickly point out that “The scale was not intended to determine reliability of the MBS procedure itself,” so we have to make sure we’re not thinking all these MBSs were of equal perfection going in.🧐
“It was intended, however, to improve consistency of documentation and recommendations across clinicians and within individual clinicians, provide a basis for comparing patients with each other and over time, and to introduce a possible measure of functional outcomes in dysphagia.” p.6
While still not 100% perfect what with the lack of “thoroughly defined parameters (i.e. what constitutes “mild retention”)” and “reliability of the actual interpretation of the videotape and subseqeunt documentation,” the scale was and can still be a good starting point for clinicians of all skillsets. Because as the saying goes, “you gotta start somewhere,” and at the very least, this can be a great step in the right direction.👍
If anything, this article further points to the fact that our profession is NOT, has never been, and most likely will not ever be a straight black-or-white, this-or-that type of field. When every patient is different, every case is different, every diagnosis is different, and every setting is different (I don’t think I need to explain how every doctor is different😉), we might end up using a lil bit of this one day, and a lil more of that the next🤓. At some point, after reviewing the research and considering our experience and setting limitations, sometimes we might need to buck up and try something out to know what works and doesn’t!
- Make sure to check out the article in full for really easy to understand and helpful tables as well as a full example of the author’s reporting format for MBSs as well as the final revised scale!!🤓🤩
- Do you use the DOSS now or have in the past?!
- Have you modified it or included with other measures you now use?!?
- What kind of experiences have you had with it?!?
- What are your thoughts on adding this to our dysphagia toolbox??
Article Referenced:
O’Neil, K., Purdy, M., Falk, J., & Gallo, L. (1999). The Dysphagia Outcome and Severity Scale. Dysphagia, 14(3), 139-145. doi: 10.1007/pl00009595