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Japanese Journal of Comprehensive Rehabilitation Science (2020)

Original Article

Value of the Hyodo score in predicting dysphagia severity,
recommended diet, and liquid consistency
Kaori Kikumura, MD,1,2 Hitoshi Kagaya, MD, DMSc,1 Seiko Shibata, MD, DMSc,1
Koichiro Matsuo, DDS, PhD,3 Fumi Toda, MD, DMSc,1 Mao Ogawa, MD, DMSc,1
Yuriko Ito, DDS, DMSc,1 Megumi Ozeki, MD, DMSc,4 Yohei Otaka, MD, PhD1
Department of Rehabilitation Medicine I, School of Medicine, Fujita Health University, Toyoake, Aichi, Japan
Department of Rehabilitation, Okinawa Kyodo Hospital, Naha, Okinawa, Japan3
Department of Dentistry and Oral-Maxillofacial Surgery, School of Medicine, Fujita Health University, Toyoake,
Aichi, Japan
4
Faculty of Rehabilitation, School of Health Sciences, Fujita Health University, Toyoake, Aichi, Japan1
2

ABSTRACT
Kikumura K, Kagaya H, Shibata S, Matsuo K, Toda F,
Ogawa M, Ito Y, Ozeki M, Otaka Y. Value of theHyodo score in predicting dysphagia severity,
recommended diet, and liquid consistency. Jpn J
Compr Rehabil Sci 2020; 11: 109-115.
Objective: To define whether the Hyodo score can beused to predict dysphagia severity and determine theappropriate diet and liquid consistency in a retrospective
observational study.
Methods: A total of 741 patients with suspected
dysphagia were enrolled. The median patient age was
77 years, and the major primary diseases were
respiratory disease and cerebrovascular disease. The
results of a videoendoscopic evaluation of swallowing
were used to determine the Hyodo score, dysphagia
severity, and recommended diet and liquid consistency.
Dysphagia severity was rated using the Dysphagia
Severity Scale (DSS). There were seven choices ofrecommended staple food, eight choices of side dish,and six choices of liquid intake.
Results: The median DSS score was 4, and the median
Hyodo score was 4. Ordinal logistic regression analysis
revealed that resting, swallowing, and the total Hyodoscores were significantly correlated to the DSS score,
recommended staple food, side dish, and liquid intake(p < 0.001).
Conclusion: The Hyodo scores are useful to predictthe dysphagia severity as well as determine theCorrespondence: Kaori Kikumura, MD
Department of Rehabilitation, Okinawa Kyodo Hospital,
4-10-55 Kohagura, Naha, Okinawa 900-8558, Japan.
E-mail: haisai8131k@yahoo.co.jp
Accepted: September 17, 2020.
Conflict of Interest: The authors declare no conflict ofinterest.
©Kaifukuki Rehabilitation Ward Association 2020
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recommended diet and liquid consistency.
Key words: dysphagia, videoendoscopic evaluationof swallowing, Hyodo score, Dysphagia Severity
Scale
Introduction
With population aging in Japan, dysphagia isincreasingly becoming a public health problem.
Dysphagia can cause undernutrition, dehydration, andaspiration pneumonia; further, it reduces the quality oflife [1‐3]. The gold standards used for assessing
dysphagia are videoendoscopic evaluation of swallowing(VE) and videofluoroscopic examination of swallowing.
VE does not require the patient to be exposed to radiationand can be performed at the bedside [4, 5]. In VE,
dysphagia is assessed by introducing an endoscope via
the nasal cavity, observing the pharynx and larynx, andthen administering a bolus and observing the swallowing
function; however, quantitative assessment is generally
difficult.
A qualitative scale called the fiberoptic endoscopic
dysphagia severity scale (FEDSS) has been developed
for assessing dysphagia in patients with acute stroke.
The FEDSS is a six-level ordinal scale; when using thescale, patients are not given an oral diet if they display
aspiration or laryngeal penetration when swallowing
saliva or a teaspoon of puree, or if they display
laryngeal penetration or aspiration without protective
reflex when swallowing a teaspoon of colored water[6, 7]. The qualitative scale commonly used in Japanto assess dysphagia is the Hyodo scoring system [8]. A
resting score is assigned for salivary pooling at thevallecula and piriform sinuses, and for glottal closurereflex at rest. In addition, induction of the swallowing
reflex and pharyngeal clearance when swallowing 3
mL of colored water are evaluated. Each element has a
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score of 0‐3 (on a four-point scale) (Table 1). Higher
Hyodo scores indicate more severe dysphagia. A total
Hyodo score of ≤ 4 indicates that the patient can safely
eat an oral diet; a score of ≥ 9 typically contraindicatesan oral diet [8‐11]. To the best of our knowledge, nostudy has shown which diets and liquids arerecommended based on each score. It is usuallynecessary to administer many different boluses ofvarying types and quantities while performing VE todetermine which diets and liquids are appropriate.
However, it is sometimes challenging for a non-expert
to determine the optimal boluses to be used. Given
that the Hyodo score is easy to calculate while
performing VE, it would be clinically useful if it could
be used to determine to a certain extent which dietsand liquids are indicated. The objective of this study
was to determine whether the Hyodo scores can beused to predict the severity of dysphagia and the ideal
diet and liquid intake levels, as assessed using various
boluses by VE.
MethodThis study was approved by our institution’s Ethics
Committee. At this institution, patients with suspected
dysphagia are screened by a certified dysphagia nurse
or a physiatrist. If a more detailed examination isrequired, written informed consent is obtained fromthe patient or a proxy, and swallowing rounds are
performed with VE [12]. VE has been performed for along time at our institution using 4-mL boluses ofliquid, so we used 4-mL boluses to determine theHyodo scores. VE was performed on 1,435 patientsfrom April 2017 to January 2020. We excluded 487
patients who were not administered 4-mL thin liquid
bolus during the examination and 207 patients forwhom insufficient data were available because thestudy was retrospective and observational; finally, 741
patients were enrolled. Of these, 503 were men and
238 were women, and the median age was 77 years(69‐84 years). The major primary disease wasrespiratory disease in 192 patients, cerebrovasculardisease in 151 patients, cancer in 108 patients,
cardiovascular disease in 79 patients, gastrointestinal
disease in 56 patients, orthopedic disease in 27
patients, neuromuscular disease in 24 patients, andother diseases in 104 patients.
Swallowing rounds are conducted at this institution
by a transdisciplinary team that includes physiatrists,
dentists, speech-language-hearing therapists, nurses,
dietitians, dental hygienists, and other specialists. The
team collaborates across disciplines to reach aconsensus on each patient, such as the patient’s
dysphagia severity as well as recommended diet andliquid consistency. For the VE, first, the pharynx andlarynx are observed; thereafter, salivary pooling isstudied, and then, the endoscope tip is touched against
the epiglottis to assess the sensation in the pharynx. A
variety of boluses, such as 4-mL thick liquid, 10-mL
thick liquid, 4-mL thin liquid, 10-mL thin liquid, a cup

Table 1. Hyodo score (quoted from reference 8).
Score

Number of cases

1 Salivary pooling at vallecula and piriform sinuses
No pooling
Slight pooling
Moderate pooling without penetration
Severe pooling and penetration into larynx during inspiration

0
1
2
3

290
307
116
28

2 Glottal closure reflex induced by touching the epiglottis with the endoscope
Prompt reflex
Weak reflex
Occationally
No reflex

0
1
2
3

370
243
61
67

3 Induction of swallowing reflex(Leading edge of bolus at the initiation of swallowing reflex by thin liquid)
Before vallecula
Vallecula
Piriform sinuses
After piriform sinuses

0
1
2
3

138
173
258
172

4 Pharyngeal clearance after swallowing thin liquid
No residues
Pharyngeal residues remain but they are washed out after 2‐3 swallows
Pharyngeal residues remain after multiple swallows
Much pharyngeal residues and penetrate into larynx

0
1
2
3

370
305
64
2

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Kikumura K et al.: Dysphagia prediction by Hyodo scoreof thin liquid, rice gruel, a pureed food, and a twophase mixture of soft rice and liquid, are administeredas required, and penetration, aspiration, induction of
the swallowing reflex, and pharyngeal clearance areobserved. The Hyodo scores were calculated based on
the observations of the pharynx and larynx and theresults of administering the 4-mL thin liquid bolus.
Dysphagia severity was assessed using the Dysphagia
Severity Scale (DSS) [13]. The DSS is a seven-level
ordinal scale wherein 1 denotes saliva aspiration; 2,food aspiration; 3, water aspiration; 4, occasional
aspiration; 5, oral problems; 6, minimal problems; and7, within normal limits. Lower numbers indicate more
severe dysphagia. The recommended staple foods
were rice, soft rice, rice gruel, thickened rice gruel,gelled rice gruel, or no staple food (forbidden); therecommended side dish was a regular diet, a soft diet,a mechanical soft diet, a mechanical soft diet withthickened liquid, a modified thickened diet, a pureed
diet, a jelly diet, or no side dish (forbidden). The
recommended liquids were thin liquid, 0.5% thickliquid, 1% thick liquid, 1.5% thick liquid, 2% thickliquid, and no liquid (forbidden).
We used the partial correlation coefficient andSpearman rank correlation coefficient to assess thecorrelation among the four elements of the Hyodoscore. We conducted an ordinal logistic regression
analysis using the Hyodo resting scores, liquidswallowing scores, and total scores as explanatory
variables, with the DSS score, recommended diet, andrecommended liquid consistency as objective variables.
Statistical significance was set at 5%. Median values
were displayed, and interquartile ranges were displayedin parentheses. The statistical software used was JMP
12 (SAS Institute Japan Inc., Tokyo), except for the
regression coefficient, odds ratio, 95% confidence
interval, and p value by ordinal logistic regression
analysis which were calculated by BellCurve for Excel(Social Survey Research Information Co., Ltd., Tokyo).

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patients, 97 aspirated the 4-mL liquid bolus, and 644
did not.
The median resting score was 1 (0‐1) for salivary
pooling at the vallecula and piriform sinuses and 1(0‐1) for glottal closure reflex at rest; the medianswallowing score was 2 (1‐2) for induction ofswallowing reflex and 1 (0‐1) for pharyngeal clearance(Table 1). The median total score was 4 (2‐5) (Figure1). The partial correlation coefficients were theminimum ( ρ = 0.047) between glottal closure reflex
and induction of swallowing reflex, while salivary
pooling and pharyngeal clearance was the maximum( ρ = 0.217). All partial correlation coefficients showedsignificant differences (Table 2).
The recommended staple food, side dish, and liquid
intake are shown in Table 3. For the analysis, given therelatively small patient population, we combined thepatients who were recommended thickened rice grueland gelled rice gruel and those recommended pureed
and jelly diets. We also created a patient group thatcomprised patients who were recommended thinliquids, those recommended 0.5‐1% thick liquid, thoserecommended 1.5‐2% thick liquid, and those who
were given no liquids orally. Ordinal logistic regression
analysis revealed that the resting and total of the Hyodoscores were significantly associated with the DSS
score, recommended staple foods, recommended side
dish, and recommended liquid consistency (p < 0.001)(Table 4). Figure 2 shows the likelihood of a given
DSS score, recommended diet, and liquid consistency
at a given Hyodo resting score and total score outputtedby JMP 12. The probability that a patient would score

Results
The median time between hospitalization and VE
was 16 days (9‐32 days). The DSS score was 2 in 50
patients, 3 in 261 patients, 4 in 176 patients, 5 in 63
patients, 6 in 141 patients, and 7 in 50 patients. The
median DSS score was 4 (3‐6), and a DSS score of 1,
the most severe level, was not observed. Of the 741

Figure 1. Distribution of Hyodo score.
The median total score was 4, while the mode was 3.
Higher Hyodo scores indicate more severe dysphagia.

Table 2. Partial correlation coefficients in Hyodo score.
Salivary pooling
Salivary pooling
Glottal closure reflex
Induction of swallowing reflex
Pharyngeal clearance

Induction ofswallowing reflex

Pharyngeal
clearance

0.168 ( p<0.001)

0.089 ( p<0.001)
0.047 ( p=0.001)

0.217 ( p<0.001)
0.102 ( p<0.001)
0.163 ( p<0.001)

0.047 ( p=0.001)
0.102 ( p<0.001)

0.163 ( p<0.001)

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0.168 ( p<0.001)
0.089 ( p<0.001)
0.217 ( p<0.001)

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Table 3. Recommended diet and liquid consistency.
Number of cases
Staple foodricesoft rice
rice gruelthickened rice gruelgelled rice gruel
none

35
212
350
6
104
34

Side dishregular dietsoft dietmechanical soft dietmechanical soft diet with thickened liquid
modified thickened dietpureed dietjelly diet
none

35
131
109
178
149
105
4
30

Liquid intake thin
0.5% thick
1% thick
1.5% thick
2% thick liquid
none

309
28
370
15
6
13

Table 4. Ordinal logistic regression analysis.
Objective variables

Explanatory
variables

Regression
Odds ratio 95% Confidence interval p Valuecoefficient

Dysphagia Severity Scale(DSS)

Hyodo resting score
Hyodo total score-0.503-0.487

0.605
0.614

0.545-0.671
0.577-0.655<0.001<0.001

Staple food

Hyodo resting score
Hyodo total score-0.467-0.408

0.627
0.665

0.575-0.684
0.621-0.712<0.001<0.001

Side dishHyodo resting score
Hyodo total score-0.466-0.423

0.627
0.655

0.570-0.690
0.620-0.692<0.001<0.001Liquid intake

Hyodo resting score
Hyodo total score-0.466-0.460

0.628
0.632

0.566-0.696
0.580-0.688<0.001<0.001

2 on the DSS when the resting score and total score
were both 0 was very small. However, dysphagia
became more severe as the scores increased, and when
the total score was 10, the probability of having a DSS
score of 2 was approximately 50%. When the total
score was 0, the probability of having a DSS score of
7 (within a normal range) was > 25%. As the Hyodoscores increased, the more difficult to aspirate staple
foods and side dishes were recommended and one
quarter of those with a total score ≥ 9 were not given
any food. Although about 60% of patients with aresting score of 0 and 80% of those with a total scoreof 0 were permitted thin liquids, as these scores
increased, thick liquids became increasingly necessary;a higher proportion of thickener was recommended,
and more patients were forbidden oral liquids.

Discussion
The present results showed that there was asignificant relationship between the Hyodo score andthe DSS score, recommended diet, and recommended
liquid consistency. In VE, the conditions in the pharynx
and larynx are observed before the boluses areadministered. In the Hyodo scoring system, a restingscore is assigned for salivary pooling at the valleculaand piriform sinuses, and glottal closure reflex at rest.
If there is no salivary pooling and good pharyngeal
sensation, the resting score will be 0, the probability ofthin liquid being permitted will be > 50%, and we canpredict that the DSS score will be ≥ 3 and that waterand food will not be forbidden. If the resting score is 6,
then it is highly probable that the DSS score will be 2
or 3, the recommended staple food will be rice gruel or

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Figure 2. Probability of dysphagia severity and recommended diet andliquid consistency by Hyodo resting score and total score.
Ordinal logistic probability plots are shown. As the Hyodo scores increased,
dysphagia deteriorated, while the recommended staple foods and side dishes
became softer and contained thickener. The necessity of thick liquids also
increased.
a: rice, b: soft rice, c: rice gruel, d: thickened or gelled rice gruel, e: regulardiet, f: soft diet, g: mechanical soft diet, h: mechanical soft diet withthickened liquid, i: modified thickened diet, j: pureed or jelly diet.
gelled rice gruel, and the side dish will be a modified
thickened diet, a pureed diet, or forbidden. In suchcases, the liquids will usually require a thickener.
Considering these facts, we can determine which
boluses will be appropriate when performing VE.
Nevertheless, it should be noted that there is a limit topredicting DSS from the Hyodo score, because DSS is
a comprehensive assessment that contains anticipatory
stage and food processing in the oral cavity, while theHyodo score measures the status and functions of thepharynx and larynx.
Previous studies have reported that safe oral
ingestion was possible with a Hyodo total score of ≤ 4,

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was difficult with a total score of ≥ 9, and that there
was a high risk of aspiration with a total score of ≥ 7[8‐11]. Figure 2 shows that food and drink were rarely
forbidden when the total score was ≤ 4 and that there
was a high probability that thick liquid was required
when the total score was ≥ 7. However, the present
results show that there was only about a 25% chanceof food and drink being forbidden, even with a total
score ≥ 9. The various types of boluses should be usedas needed in VE, and the staple food, side dish, andliquid after examination can be adjusted to achievereasonable oral intake.
The present study had certain limitations. The

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Kikumura K et al.: Dysphagia prediction by Hyodo scoreoriginal method for assessing the Hyodo score
recommends the use of a 3-mL bolus of liquid to be
swallowed, but 4-mL boluses were administered inthis retrospective study. Care must be taken ininterpreting the results as they were obtained by notexactly the same method. However, when severe
dysphagia is suspected, there is a higher risk of liquid
aspiration, and in some cases a jelly is used [14]. An
assessment scale using gelatin jelly called the HyodoKomagane score has been developed [15]. Thin liquids
are more easily aspirated than thick liquid [16‐18];
therefore, when performing VE at our institution, we
generally administer a thick liquid bolus first, and incase of aspiration, a thin liquid bolus is not typicallyadministered. In our previous study wherein VE wasperformed on 998 hospitalized patients, 7% of thepatients had a DSS score of 1, and 31% had a score of
2 [12]; thus, the cases in the present study were clearlyless severe. Thin liquids are not administered in more
severe cases of dysphagia; therefore, we believe thatfurther research is necessary to determine the Hyodoscores assessed using thick liquids or jelly. The present
study was a retrospective observational study thatinvestigated the food and drink recommended basedon the VE results. Given that the diets and liquidconsistencies were ultimately decided by the physician
in charge at the time, they were affected by the patient’s
overall condition, complications, and comorbidities
and do not necessarily correspond to the diets and liquidconsistencies that would have been recommended
based on a diagnosis of dysphagia alone. Moreover,many patients in the present study had respiratory or
cerebrovascular disease, and we must consider theeffects that the differences in the primary disease would
have had on the results. Furthermore, the present study
was only conducted at a single institution; therefore,
further studies at multiple institutions are needed tostandardize the results.
In conclusion, the Hyodo scores consist of observing
the pharynx and larynx, and assessing the ability toswallow colored water was useful to predict the dysphagia
severity as well as determine the recommended diet andliquid consistency. Further studies in multiple facilities
are needed.
Acknowledgements
The authors thank Yuki Nagashima, DDS, Hidetaka
Tsuzuki,DDS, PhD, Shigeru Tamura, RN, Miyo
Yamasaki, RN, Ayumi Inagaki, RN, and Mayumi
Ikeda, RN for their cooperation in swallowing rounds.

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