Volume 73, No.1: 2021 Siriraj Medical Journal

https://he02.tci-thaijo.org/index.php/sirirajmedj/index

Original Article

SMJ

Sirichai Wilartratsami, M.D., Borriwat Santipas, M.D., Panya Luksanapruksa, M.D., Surin anapipatsiri,

M.D., Visit Vamvanij, M.D.

Department of Orthopedic Surgery, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, ailand.

Reliability and Validity of the Thai Version of the

Modied Japanese Orthopaedic Association Score

(mJOA score)

ABSTRACT

Objective: To evaluate the reliability and validity of the ai version of the modied Japanese Orthopaedic

Association scale.

Methods: e modied Japanese Orthopaedic Association scale was translated into ai language to create the

ai version of the Modied Japanese Orthopaedic Association (ai-mJOA) scale. Translation was performed

according to international standards using a forward-backward translation protocol. Translation was performed

by 2 expert translators and 1 physician, and the nal version was approved by an expert committee. ai patients

with cervical spondylosis with myelopathy were enrolled and evaluated using the ai-mJOA scale, Nurick Grading,

the ai version of the Neck Disability Index (ai-NDI), and the ai version of the Short Form-36 (ai-SF-36).

Reliability and validity of the ai-mJOA were assessed via comparison with the Nurick Grading and the ai-NDI.

Results: Ninety-two patients were included. e most common compression level was C5-C6 vertebral disc.

Cronbach’s alpha of the total ai-mJOA showed excellent internal consistency (0.991). e intraclass correlation

coecient (ICC) for test-retest reliability was 0.981 (95% condence interval [CI]: 0.972-0.988). Regarding concurrent

validity, the motor dysfunction score of the lower extremities and the total score of the ai-mJOA were strongly

correlated with Nurick Grading (r=0.825, r=0.712, respectively). e total score of the ai-mJOA was moderately

correlated with the ai-NDI (r=0.670).

Conclusion: e ai-mJOA was found to be a valid and reliable tool for evaluating symptom severity in ai

patients with cervical spondylosis with myelopathy.

Keywords: Reliability; validity; ai version; Modied Japanese Orthopaedic Association Score; ai-mJOA (Siriraj

Med J 2021; 73: 55-60)

Corresponding author: Visit Vamvanij

E-mail: drvisitvam@gmail.com

Received 3 September 2020 Revised 24 September 2020 Accepted 25 September 2020

ORCID ID: http://orcid.org/0000-0002-6056-0961

http://dx.doi.org/10.33192/Smj.2021.08

INTRODUCTION

Cervical spondylosis with myelopathy (CSM) is one

of the most common progressive spinal degenerative

conditions in elderly patients, and the neurological

symptoms of CSM include neck pain, weakness, and

numbness of extremities, and gait dysfunction.

Functional

disability plays a key role in the treatment decision-making

process. Surgery is not superior to conservative treatment

in patients with mild symptoms. Law, et al. previously

described several poor prognostic factors that they found

to be associated with conservative treatment, including

progression of symptoms, presence of myelopathy for

more than six months, a compression ratio approaching

0.4, and transverse area of the cord <40 mm.

However,

Volume 73, No.1: 2021 Siriraj Medical Journal

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these factors include the imaging of the spine, which

may not be applicable in some settings.

Currently, the most commonly utilized scales for

evaluating the severity of symptoms are Nurick grading,

the Neck Disability Index (NDI),

and the modied

Japanese Orthopaedic Association (mJOA) scale.

e

mJOA scale is multidimensional, and it is used to separately

assess the function of upper and lower extremities and

bladder function in CSM patients. e mJOA has been

widely used to standardize the clinical assessment of

CSM.

e mJOA has been translated into several languages,

including Italian

, Brazilian-Portuguese

, and Dutch.

is study aimed to translate and adapt the mJOA to

the ai language, and to determine its reliability and

validity among ai patients with CSM.

MATERIALS AND METHODS

Questionnaire

e mJOA scale was designed to assess micturition

and motor function and sensation of the extremities in

patients with CSM. e mJOA has an 18-point scale

that consists of motor dysfunction of upper extremities

(5 points), motor dysfunction of lower extremities

(7 points), sensory dysfunction of upper extremities

(3 points), and sphincter dysfunction (3 points). A score of

18 shows no neurological decits, whereas an increasingly

lower score represents an increasingly greater severity

of functional impairment and disability.

e mJOA was translated into the ai language

according to linguistic validation guidelines using a forward-

backward translation protocol to create the ai-mJOA.

is process involved independent translation of the

mJOA from English to ai by both a professional English

translator and a bilingual physician. e two independent

translations were then discussed and combined into a

consensus version. e backward translation from ai

to English was performed by a native English speaker

who is a professional translator of the ai language

to the English language. e English translation was

then compared to the original mJOA questionnaire and

checked for mistranslation and misunderstanding.

Participants

is study was approved by the Siriraj Institutional

Review Board (SIRB) of the Faculty of Medicine Siriraj

Hospital, Mahidol University, Bangkok, ailand [COA

no. 328/2016(EC1)], and written informed consent was

obtained from all participants. Enrolled patients were

prospectively recruited from the in-hospital spinal

surgery unit at Siriraj Hospital during December 2016

to November 2019. During this period, 92 patients with

CSM that were scheduled for surgical treatment were

enrolled. All patients were assessed using the Thai-

mJOA, Nurick grading, and the ai-NDI

on the day

of admission, and once again 72 hours aer surgery.

Outcome measurement

To assess test-retest reliability, all patients were asked

to complete the ai-mJOA on the day of admission

before surgery, and then once again 3 days aer surgery.

Test-retest reliability was determined using intraclass

correlation coecient (ICC). Reliability was determined

by calculating Cronbach’s alpha. Internal consistency

estimates of >0.70 were considered acceptable for group

comparisons.

Concurrent validity was evaluated by comparing the

ai-mJOA with the Nurick grading scale and the ai-

NDI. Validity was determined by calculating Spearman’s

correlation coecient. Correlation coecients of 0.1 to

0.3 were considered weak; 0.3 to 0.6, moderate; and >0.6,

strong. All statistical analyses were performed using

SPSS v.18.0.

RESULTS

Ninety-two patients were enrolled in this study,

and most subjects were male (63.04%). Approximately

one-third of patients each had 1, 2, and 3 levels of cervical

spinal cord compression (34.4% had 1 level, 31.1% had 2

levels, and 31.1% had 3 levels). Demographic and clinical

data of patients, including scoring of the ai-mJOA,

the Nurick grading scale, and the ai-NDI, are shown

in Table 1.

e Cronbach’s alpha values were acceptable for

all domains of the ai-mJOA, as follows: 0.991 for the

total score, 0.990 for Motor dysfunction score of the

upper extremities, 0.997 for Motor dysfunction score

of the lower extremities, 0.945 for Sensory dysfunction

score of the upper extremities, and 0.977 for Sphincter

dysfunction score. For the test-retest evaluation, the ICC’s

were 0.981 (95% condence interval [CI]: 0.972-0.988) for

the total score, 0.98 (95% CI: 0.97-0.987) for the Motor

dysfunction score of the upper extremities, 0.995 (95%

CI: 0.992-0.997) for the Motor dysfunction score of the

lower extremities, 0.896 (95% CI: 0.847-0.930) for the

Sensory dysfunction score of the upper extremities, and

0.955 (95% CI: 0.933-0.97) for the Sphincter dysfunction

score. ese ICC values indicate good repeatability for

each domain. Details of ICC and test-retest results are

shown in Table 2. We also reported the Cronbach’s

alpha values and ICCs of a previous study compared to

our values from the present study in Table 4.

Wilartratsami et al.

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Original Article

SMJ

TABLE 1. Demographic and clinical characteristics of the study population.

TABLE 2. Reliability of the ai-mJOA scale (N=92).

Characteristics (N = 92)

Gender

Male 58 (63.04%)

Female 34 (36.96%)

Number of neurological compression levels

1 31 (34.4%)

2 28 (31.1%)

3 28 (31.1%)

4 3 (3.3%)

Level of neurological compression

C2-C3 1 (1.1%)

C3-C4 37 (41.6%)

C4-C5 55 (61.8)

C5-C6 63 (70.8)

C6-C7 24 (27%)

C7-T1 0 (0.0%)

Thai-mJOA score 11.9±3.5 (4-18)

Nurick grading score 2.8±1.2 (0-5)

Thai-NDI score 37.7±17.4 (2-78)

Data presented as number and percentage or mean ± standard deviation (range)

Abbreviations: C = cervical; T = thoracic; ai-mJOA = ai version of the modied Japanese Orthopaedic Association; ai-NDI = ai

version of the Neck Disability Index

Scoring parameters Cronbach’s Test-retest

Floor Ceiling

alpha ICC (95% CI)

Thai-mJOA scale

Total 0.991 0.981 (0.972-0.988) 0.0% 5.4%

Motor dysfunction score of the upper extremities 0.990 0.980 (0.970-0.987) 0.0% 38.0%

Motor dysfunction score of the lower extremities 0.997 0.995 (0.992-0.997) 1.1% 17.4%

Sensory dysfunction score of the upper extremities 0.945 0.896 (0.847-0.930) 1.1% 14.1%

Sphincter dysfunction score 0.977 0.955 (0.933-0.970) 4.3% 73.9%

Abbreviations: ICC, intraclass correlation coecient; CI, condence interval; ai-mJOA scale, ai version of the modied Japanese

Orthopaedic Association scale

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TABLE 3. Correlation coecients between ai-mJOA score and Nurick grading score and the ai NDI score as

determined by Spearman’s correlation coecient.

Thai-mJOA scale

Motor Motor Sensory

Scoring system Total dysfunction dysfunction dysfunction Sphincter

score score of score of score of dysfunction

the upper the lower the upper score

extremities extremities extremities

Nurick grading -0.712 -0.404 -0.825 -0.273 -0.348

Thai-NDI -0.670 -0.574 -0.570 -0.371 -0.325

TABLE 4. Cronbach’s alpha values and test-retest ICC of present study and previous study.

Longo, et al. The present

(2016)

study

Language Italian Thai

Number of patients 75 92

Total Score 0.6 0.991

Motor dysfunction score 0.45 0.99

of the upper extremities

Cronbach's alpha Motor dysfunction score 0.54 0.997

of the lower extremities

Sensory dysfunction score 0.58 0.945

of the upper extremities

Sphincter dysfunction score 0.6 0.977

Total score 0.91 0.981

(0.972-0.988)

Motor dysfunction score 0.892 0.980

of the upper extremities (0.970-0.987)

Test-retest ICC Motor dysfunction score 0.929 0.995

(95% CI) of the lower extremities (0.992-0.997)

Sensory dysfunction score 0.924 0.896

of the upper extremities (0.847-0.930)

Sphincter dysfunction score 0.93 0.955

(0.933-0.970)

Abbreviations: ai-mJOA = ai version of the modied Japanese Orthopaedic Association; ai-NDI = ai version of the Neck Disability

Index

Abbreviations: ICC = intraclass correlation coecient; CI = condence interval

Wilartratsami et al.

Volume 73, No.1: 2021 Siriraj Medical Journal

https://he02.tci-thaijo.org/index.php/sirirajmedj/index

Original Article

SMJ

Concurrent validity of the ai-mJOA compared

to Nurick grading and the ai-NDI is described in

Table 3. e most strongly correlated domains were

Nurick grading with the Motor dysfunction score of the

lower extremities of the ai-mJOA (-0.825), and Nurick

grading with the total score of the ai-mJOA (-0.712).

e ai-NDI was also shown to be strongly correlated

with the total score of the ai-mJOA (-0.670).

A Bland-Altman plot showing the dierence between

the pre-operative mJOA and post-operative mJOA plotted

against the mean of the two scores is shown in Fig 1.

e arithmetic mean dierence between the two score

(the bias) was 0.1648 (95% CI: -0.01191 to 0.3178). e

upper and lower limits of agreement were 1.6041 and

-1.2744, respectively.

DISCUSSION

In the present study, the modied Japanese Orthopaedic

Association scale was translated into ai language using

a forward-backward translation protocol to create the

ai-mJOA. e results showed good reliability and

validity of the ai-SSS questionnaire, which correlated

with both the Nurick grading scale and the ai-NDI.

e Cronbach’s alpha of total score and each domain

ranged from 0.945-0.997, which demonstrate excellent

internal consistency, and these values are consistent

with the Cronbach’s alpha values (range: 0.813-0.826)

previously reported by Yonenobu, et al.

We also found

that the ai-mJOA has excellent reliability. e ICCs

for test-reliability for all domains ranged from 0.896 to

0.995, which also agreed with the previous ndings of

Yonenobu, et al.

Our analysis for concurrent validity

revealed a significant strongly negative correlation

between the Nurick grading scale and the total score

of ai-mJOA, and with the Motor dysfunction score

of the lower extremities domain of the Thai-mJOA

(Spearman’s correlation coecient: -0.712 and -0.825,

respectively). e ai-NDI was also found to be strongly

negatively correlated with the total score of the ai-mJOA

(Spearman’s correlation coecient: -0.67). ese ndings

resulted from dierences in interpretation between the

ai-mJOA and the Nurick grading scale, and between

the ai-mJOA and the ai-NDI. More specically,

severe functional disability is indicated by a lower score

on the ai-mJOA, but by a higher score on the Nurick

grading scale and the ai-NDI.

CONCLUSION

e original modied Japanese Orthopaedic Association

scale was successfully translated to ai language to create

the ai-mJOA. e ai-mJOA was found to be a valid

and reliable tool for evaluating symptom severity in ai

patients with cervical spondylosis with myelopathy.

ACKNOWLEDGMENTS

e authors gratefully acknowledge Professor Dr.

Edward C. Benzel for giving us the permission to translate

the modied Japanese Orthopaedic Association (mJOA)

Fig 1. Bland-Altman plot showing the dierence between the pre-operative mJOA and post-operative mJOA plotted against the mean of

the two scores

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scale into ai language, and Ms. Nhathita Panatreswas

of the Division of Research, Department of Orthopaedic

Surgery, Faculty of Medicine Siriraj Hospital, Mahidol

University for assistance with data collection and statistical

analysis.

Conict of interest declaration

e authors hereby declare no personal or professional

conicts of interest relating to any aspect of this study.

Funding disclosure

is study was funded by a grant from the Faculty

of Medicine Siriraj Hospital, Mahidol University [grant

no. (IO) R015932036].

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