Short ‘n Sweet – D.I.G.E.S.T.

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Not only is the acronym name 🤩PERFECT🤩, but the whole purpose and background behind the Dynamic Imaging Grade of Swallowing Toxicity make it truly a work that pushes our field further while continuing closer collaboration with other respected professions (which is always needed in any setting, treatment plan, and patient care). I’m not gonna lie, I’ve been wanting to learn more about this ever since I saw Dr. Hutcheson present on it at Dysphagia Research Society a few years ago, so I couldn’t wait to dive in!

Get ready to digest delicious info on this functional-outcome rating measure that YOU voted on and savor all the possibilities!🤤

The swallowing mechanism alone is highly complex.

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Add in dysphagia to disrupt the process, and it gets even more complicated.

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Then, mix in any specific population group, and you might end your day with finding yourself feeling like an SLP Sherlock Holmes when it comes to finding all the pieces of the puzzle, let alone trying to make sense of them to put together🧐! With the Head&Neck Cancer (HNC) population, there are also a plethora of professions that can be involved in this delicate circumstance, who collectively tend to acknowledge the essentialness of swallowing within this population.

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“Swallowing is a functional priority top-ranked by patients before and after HNC treatment and is an independent driver of quality of life in survivorship. Pharyngeal dysphagia also significantly contributes to potentially life-threatening secondary morbidity during survivorship, including pneumonia and malnutrition.” p.5

Luckily, the expert authors and creators knew to align their swallow outcome measures closely with teams like The NCI’s Common Terminology Criteria for Adverse Events (CTCAE), which “serves as the universal framework for toxicity reporting in oncology trials. CTCAE offers standardized language and criteria for clinician-graded toxicity.” Because apparently there’s no consensus on “an optimal MBS parameter to use as an endpoint measure in these trials.

So with this framework in mind, the authors wanted to combine these two worlds in order to enhance our patients’ outcomes and overall care.

“DIGEST is a bolus-anchored functional-outcome measure designed to reflect NCI’s CTCAE framework for grading toxicities ofcancer therapy p.5

Those behind this endeavor was nothing short of an SLP’s dream team think-tank that included 10 total hours of consensus between:

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  • 9 expert clinician-researchers (min 10 yrs specialized HNC clinical experience)
  • 6 clinician-scientists
  • 3 senior BCS-S clinicians involved in prior HNC research projects

What are they specifically looking at?👀

  1. Safety profile (reflecting Penetration-Aspiration Scale (PAS)
  2. Efficiency profile (estimation of % pharyngeal residue)

Unanimous panelist agreement indicated that PAS and ‘ordinal residue grades’ were a relevant way to measure the pharyngeal phase of swallowing safety/efficiency, respectively. The investigators also included an easy-to-digest graphic reminding us of the general effects of each of these (which is really what it’s all about):

Figure 1 (Original Reference)

Next, to actually come up with all the data the investigators looked at 100 randomly selected MBSs conducted pre/post (surgical or nonsurgical) organ preservation over an 8-year period at MD Anderson Cancer Center, and then to make sure there was enough diversity for pre-treatment and normal/abnormal, smaller samples of that sample were selected and re-analyzed/rated, with 2 blinded raters scoring the original 100 MBSs. Because these authors really know their stuff, “the standard MBS protocol”º was administered.

Beyond just the general HNC populationº, the authors excluded specifically patients with histories of recurrent/second primary HNC at the time of MBS and those being treated with open transcervical or transmandibular HNC surgery.

  • average age: 61 y/o (47-84 y/o range)
  • 82% male
  • 72% treated with chemoradiation

A quick refresher for all the ways to show validity and reliability (because shouldn’t we wanna know what we’re using is actually good-quality😉?!):

  • Intra-rater reliability= measure of how consistent an individual is at measuring a constant phenomenon
    • (which was excellent for both raters)
  • Inter-rater reliability= how consistent different individuals are at measuring the same phenomenon
    • (which was almost perfect for efficiency and substantial for safety)
  • Criteria validity= measures how well one measure predicts an outcome for another measure
    • (which were significant for all the measures used: pharyngeal pathophysiologyº, swallow efficiencyº, perceived dysphagiaº, and oral intakeº)
  • Construct validity= the extent to which the measure ‘behaves’ in a way consistent with theoretical hypotheses
    • (which was substantial indicating a good relationship between the MBS criteria and the CTCAE framework)

Ok, now for the good stuff😁🤩. . .

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1️⃣ How great is it that the investigators specifically did NOT want fancy-schmancy equipment or calculations for this tool!👏👏👏 (While they praise the NRRSº for residue, they also seem to completely understand the practical limitations😉)

2️⃣ I think equally helpful was how they really considered the best way to measure things, such as residue using the frequent and reliable ordinal scales and ranges like “<10%” and “50-90%” with “Majority of residue” making it simpler for us fast-moving, barium-spilling clinicians

3️⃣ The authors also give some additional recommendations to pair additional “complementary functional measures” for oral intakeº and patient-reported questionnairesº

🛑 And lastly, I will shout it from the rooftops how I 😍LOVE😍 that this measure keeps going above and beyond with not only giving us a way to measure and document changes in safety, not only efficiency, but also allows us to “grade” and rate the overall profile of the dysphagia picture (the authors give us an example to relate to like the GRBAS classification of voice profiles!):

“For instance, a DIGEST profile of S0 E1 D1 reflects safe (S0) but mildly inefficient (E1) pharyngeal bolus transit and represents overall mild pharyngeal dysphagia (D1). However, a DIGEST profile of S3 E1 D3 reflects a swallow with severe safety compromise (S3) and mild inefficiency (E1) of bolus transit and equates to overall severe pharyngeal dysphagia (D3).” p.7

What this really means?

A more reliable, valid way of documenting the pharyngeal swallow components in safety & efficiency, and how these results might translate into the overall concept of swallow impairment!!

If that doesn’t sound amazing and make you wanna flip out of your fluoro chair😱🤩. . .

Is your head spinning with all this mind-blowing info🤯? Because the article is 💥FREE ACCESS💥 if you need a much clearer picture of what this all actually looks like, scroll to the bottom for an easier and more digestable😉 image the authors graciously provide…..

Some extra things to keep in mind:

“Critical elements of standardization include, among many, the contrast agent, the bolus protocol, the frame rate of image acquisition, and the patient instructions.

A uniform bolus protocol must be efficient to minimize radiation exposure (per the as-low-as-reasonably-achievable principle) yet feature a sufficient range of consistencies to assess swallow capacity.” p.5

That’s a big nod to you MBSImP,™ since the authors specifically go on to state “The effect of testing additional bolus types on the psychometric properties of DIGEST has not been evaluated.” So if you’re thinking you’re gonna go rogue during your fluoro with the DIGEST tool, I would probably think twice or hope the authors don’t come knocking because really, all this guidance is not about us, it’s for our patients’ safety and overall care😉.

Additionally, because DIGEST is more of a clinician-rated pharyngeal measure, the authors are quick to point out this measure should ❌NOT❌ replace “more elegant, validated measures of biomechanical, kinematic, physiologic, and temporal parameters of the swallow” that can also be critically essential in the pathophysiology of dysphagia. (And there are so, so many out there🥴). And really, is anything ever a “one-and-done” in our field anyway?😉

“To use DIGEST as a clinical decision-making tool, the clinician must also consider a host of concomitant factors, including the patient’s respiratory status, general wellness, mental functioning, and compensatory abilities. As such, although we are hopeful that DIGEST offers an ideal tool for risk stratification, DIGEST alone cannot be used to render clinical decisions about oral intake and dysphagia therapy.” p.8

So while the investigators admit their streamlined MBS measure is not the end-all-be-all, it can be a great tool used the right way, with the right patients, at the right time.👍

Do you or have you used DIGEST?!

What are more thoughts on its clinical utility?

One more final addition because I almost overlooked all these FEES-possibilities😉:

A recent 2021 💥FREE ACCESS💥 article (that also provides an equally great image representing the overall grading process) used many of the same measures and methods to conclude:

“DIGEST-FEES is a valid and reliable scale to describe the severity of pharyngeal dysphagia in patients with HNC.” p.1

(I highly recommend still checking out the article to know a bit more about some limitations and just how they came to this conclusion though!!😉🤓)

Here’s that awesome overview of DIGEST grading criteria:

Figure 2 Original image from Reference

And another just for more proof of how to map all this out:

Table 4 Original image from Reference

Articles Referenced: [FREE ACCESS]

Hutcheson, K., Barrow, M., Barringer, D., Knott, J., Lin, H., & Weber, R. et al. (2016). Dynamic Imaging Grade of Swallowing Toxicity (DIGEST): Scale development and validation. Cancer, 123(1), 62-70. doi: 10.1002/cncr.30283

Starmer, H., Arrese, L., Langmore, S., Ma, Y., Murray, J., & Patterson, J. et al. (2021). Adaptation and Validation of the Dynamic Imaging Grade of Swallowing Toxicity for Flexible Endoscopic Evaluation of Swallowing: DIGEST-FEES. Journal Of Speech, Language, And Hearing Research, 64(6), 1802-1810. doi: 10.1044/2021_jslhr-21-00014

(And a recent small refinement of the measure:)

Hutcheson, K. A., Barbon, C., Alvarez, C., & Lewin, J. S. (2020). Refining measurement of mild safety impairment (safety grade 1) in the DIGEST criteria: Validation of DIGEST v2. Poster Presentation at the Dysphagia Research Society Annual Meeting.


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