Current affiliation: Hye Min Ji (Department of Physical Medicine and Rehabilitation, Veterans Health Service Medical Center, Seoul, Korea)
To systematically translate the Duchenne muscular dystrophy Functional Ability Self-Assessment Tool (DMDSAT) into Korean and verify the reliability and validity of the Korean version (K-DMDSAT).
The original DMDSAT was translated into Korean by two translators and two pediatric physiatrists. A total of 88 patients with genetically confirmed Duchenne muscular dystrophy (DMD) participated in the study. They were evaluated using the K-DMDSAT once as a self-assessment and once by an interviewer. The interviewer evaluated the K-DMDSAT again 1 week later using a test-retest approach. The intraclass correlation coefficient (ICC) was used to verify the interrater and test-retest reliabilities. Pearson correlation analysis between the K-DMDSAT and the Brooke or Vignos scales were used to assess validity.
The total score and all domains of the K-DMDSAT showed excellent interrater and test-retest reliability, with an ICC for total scores of 0.985 and 0.987, respectively. All domains had an ICC >0.90. From the Pearson correlation analysis, the total K-DMDSAT score was significantly correlated with the Vignos and Brooke scales (r=0.918 and 0.825, respectively; p<0.001), and each domain of K-DMDSAT showed significant correlation with either the Vignos or Brooke scales.
DMDSAT was systematically translated into Korean, and K-DMDSAT was verified to have excellent reliability and validity. K-DMDSAT can help clinicians easily describe and categorize various functional aspects of patients with DMD through the entire disease progression.
Duchenne muscular dystrophy (DMD) is the most common congenital muscular dystrophy, affecting approximately one in 5,000 live male births [
The Duchenne muscular dystrophy Functional Ability Self-Assessment Tool (DMDSAT) is a patient-reported outcome scale developed to assess and describe the functional status of patients with DMD throughout the entire disease course [
Furthermore, Landfeldt et al. [
DMDSAT comprises four domains:
In the
In the
With the sum of scores of all four domains, the total score of the DMDSAT ranges between 0 and 23, with a higher score representing a higher functional activity or level of independence.
K-DMDSAT was developed by translating and reverse-translating the questionnaires. Before beginning the procedure, approval via e-mail was obtained from the original author and Newcastle University, the copyright-holders of DMDSAT. Forward translation was performed by a professional translator and reviewed by two Korean pediatric physiatrists fluent in both English and Korean (
Patients diagnosed with DMD who visited the pediatric outpatient clinic of our hospital between April 2020 and October 2021 were recruited for this study. DMD diagnosis was confirmed using a dystrophin gene study. To identify dystrophin mutations, multiplex polymerase chain reaction and direct sequencing (Xp21.2-p21.1, exons 1–79) were performed. If the deletion or duplication tests yielded negative results, dystrophin gene sequencing was performed to search for point mutations or small deletions or insertions. Written informed consent was obtained from all participants after explaining the purpose and content of this study. Patients or caregivers who could not fully understand the written questionnaires were excluded. A total of 88 patients agreed to participate, and none dropped out during the study. This study was conducted in accordance with the Declaration of the World Medical Association and was reviewed and approved by the Institutional Review Board (IRB) of Seoul National University Hospital (IRB No. H-2106-062-1225).
This study was conducted to verify the interrater and test-retest reliability of K-DMDSAT. On the day of participation, patients were asked to complete the K-DMDSAT without assistance. However, in cases where the patient could not comprehend or understand the questions owing to a lack of reading ability, a proxy writer was allowed if he was living with parents or caregivers with whom he had a continuous relationship.
On the same day as the self-assessment, an interviewer asked questions on the DMDSAT items and recorded their responses to fill out the K-DMDSAT. The same interviewer once more evaluated the participants 1 week after the first evaluation. The K-DMDSAT score was measured, provided that participants did not experience any important medical or functional change in clinical status in a week. During the entire research period, the patient’s self-report of K-DMDSAT took approximately 10 minutes, and the interview took approximately 5 minutes. All assessments were performed at the outpatient clinic of the Department of Pediatric Rehabilitation Medicine.
The DMDSAT scores by self- and interviewer assessment were compared to verify interrater reliability, and results from the first and second assessments by the interviewer were compared to verify test-retest reliability. The intraclass correlation coefficient (ICC) was used for statistical analysis, where values between 0.74 and 1.0 represented excellent reliability, 0.60 and 0.74 represented good reliability, 0.40 and 0.59 represented fair reliability, and <0.4 represented poor reliability.
In this study, the Brooke scale [
The interrater reliability of K-DMDSAT was significant for the total score and all 4 K-DMDSAT domains (
Similar results with interrater reliability were observed for the test-retest reliability (
Pearson correlation analysis showed a significant correlation between the total score of the K-DMDSAT and the Vignos and Brooke scales (r=0.918 and 0.825, respectively, p<0.001). Specifically, the
This study was designed to translate DMDSAT into Korean and investigate the reliability and validity of KDMDSAT. Results showed that K-DMDSAT had excellent interrater and test-retest reliability and validity, which supports using K-DMDSAT in clinical practice.
Similar results were reported by Landfeldt et al. [
Although K-DMDSAT is a patient-reported outcome scale, it shows excellent interrater reliability. There are several possible reasons for this finding. First, the questionnaires are simple and easy to understand since the measure is designed to be completed by patients or caregivers who are not health professionals. Moreover, the questionnaires were about daily activities performed every day, not specific tasks, meaning that the respondents could easily fill out the assessment tool without profoundly thinking. Second, the items for each domain are listed in order of difficulty, which helps recognize the patient’s current function. Finally, because the time to complete the assessment is less than 10 minutes, a more reliable response can be expected with low fatigue and higher compliance.
Since there is a consensus that motor function, which reflects activities of daily living, is more clinically relevant than conventional motor examination, such as manual muscle testing, for assessing patients with muscular dystrophy [
The Comprehensive Functional Scale for DMD (CFSD) [
The Egen Klassifikation (EK) scale was also designed for the same purpose and extended in 2008 to include more functional abilities, including swallowing function (e.g., food textures) and distal hand function (e.g., ability to control joystick) [
Compared to these two well-validated comprehensive scales, the CFSD and EK scales, the DMDSAT lacks items assessing other aspects of DMD, especially dysphagia and pain. Since dysphagia and pain are symptoms that require careful attention and are strongly associated with quality of life [
In addition, we believe a supplementary item should be considered for the scoring system of the ventilatory support domain of DMDSAT. Most patients typically begin ventilator use at night and eventually increase use during the day if there is dyspnea during the day or elevated daytime carbon dioxide levels despite adequate night treatment [
This study had several limitations. Among the participants, only 11 (12.5%) patients received ventilator support. The mean score of each K-DMDSAT domain for this population was 1.63±1.29 for the arm function domain, 0.27±0.46 for the mobility domain, and 0 for the transfer domain. There might have been a bottom effect, though it was not investigated in the current study. Since there has been considerable improvement in the life span of patients with DMD owing to advances in standards of care, especially in respiratory management [
In conclusion, DMDSAT was systematically translated into Korean, and K-DMDSAT was verified to have excellent reliability and validity. K-DMDSAT is a short, clinically relevant assessment tool for patients with DMD that can be rapidly administered without assistantance. K-DMDSAT can help clinicians easily describe functional levels comprehensively at different stages of disease progression.
No potential conflict of interest relevant to this article was reported.
None.
Conceptualization: Ji HM, Shin HI. Methodology: Ji HM, Hyun SE, Shin HI. Formal analysis: Lee K, Ji HM. Project administration: Lee K, Ji HM. Visualization: Lee K. Writing – original draft: Lee K. Writing – review and editing: Lee K, Shin HI, Hyun SE, Ji HM. Approval of final manuscript: all authors.
Clinical characteristics of participants
Characteristic | Value (n=88) |
---|---|
Demographics | |
Age (yr) | 16.63±5.09 (8–35) |
Ambulatory status | |
Ambulant | 30 (34.1) |
Nonambulant | 58 (65.9) |
Time since loss of ambulation (yr) | 6.14±4.43 (0–18) |
Ventilatory support | |
All day | 4 (4.5) |
At night only | 7 (8.0) |
Not used | 77 (87.5) |
Brooke/Vignos scale | |
Brooke scale | 2.67±1.67 (1–6) |
Vignos scale | 6.77±3.23 (1–10) |
K-DMDSAT | |
|
4.65±1.69 (1–6) |
|
1.82±1.78 (0–5) |
|
3.49±4.16 (0–10) |
|
1.83±0.49 (0–2) |
Total score | 11.60±7.16 (1–23) |
Values are presented as mean±standard deviation (minimum–maximum) or number (%).
K-DMDSAT, Korean version of the Duchenne muscular dystrophy Functional Ability Self-Assessment Tool.
Interrater reliability of the K-DMDSAT (n=88)
K-DMDSAT | Self | Interviewer | ICC |
---|---|---|---|
Total score | 11.60±7.16 | 11.73±7.40 | 0.985 |
4.65±1.69 | 4.67±1.61 | 0.914 |
|
1.82±1.78 | 1.82±1.86 | 0.982 |
|
3.49±4.16 | 3.44±4.29 | 0.978 |
|
1.83±0.49 | 1.80±0.53 | 0.942 |
Values are presented as mean±standard deviation.
K-DMDSAT, Korean version of the Duchenne muscular dystrophy Functional Ability Self-Assessment Tool; ICC, intraclass correlation coefficient.
p<0.001.
Test-retest reliability of the K-DMDSAT (n=88)
K-DMDSAT | Test | Re-test | ICC |
---|---|---|---|
Total score | 11.73±7.40 | 11.42±7.61 | 0.987 |
4.67±1.61 | 4.72±1.63 | 0.961 |
|
1.82±1.86 | 1.70±1.96 | 0.987 |
|
3.44±4.29 | 3.24±4.23 | 0.973 |
|
1.80±0.53 | 1.76±0.55 | 0.970 |
Values are presented as mean±standard deviation.
K-DMDSAT, Korean version of the Duchenne muscular dystrophy Functional Ability Self-Assessment Tool; ICC, intraclass correlation coefficient.
p<0.001.
The questions below describe the levels of activity for arm function, mobility, transfers, and need for ventilatory support. The activities are intended to be in order of difficulty, and we would like you to
Arm function | |
---|---|
Can put an item such as a book onto a shelf above shoulder height | ● |
Can lift at least one arm above the head | ● |
Can lift at least one arm to shoulder height | ● |
Can eat a meal without any help | ● |
Needs help to cut up food but can feed and drink independently | ● |
Needs help to drink or feed | ● |
Can pick up objects (e.g., pen/money) | ● |
Can move fingers (e.g., press on mobile or other electronic device) | ● |
Cannot move fingers | ● |
Mobility | |
---|---|
Walks independently outdoors for long distances (>1 km) | ● |
Walks independently outdoors for medium distances (<1 km) | ● |
Walks independently outdoors for short distances (e.g., to a car) | ● |
Walks outdoors with help from a person | ● |
Walks indoors independently but requires a wheelchair outdoors | ● |
Walks indoors with help from a person and requires a wheelchair outdoors | ● |
Uses a wheelchair indoors and outdoors | ● |
Uses a wheelchair but unable to use it in some situations (e.g., cold weather) | ● |
Unable to control the wheelchair without help | ● |
Transfers | Can do independently | Can do with help | Need to be lifted or hoisted, or cannot |
---|---|---|---|
Get on and off the floor | ● | ● | ● |
Get in and out of a chair | ● | ● | ● |
Get in and out of bed | ● | ● | ● |
Get on and off the toilet | ● | ● | ● |
Go up and down stairs | ● | ● | ● |
Ventilatory support | Not ventilated | Ventilated at night | Ventilated during day and night |
---|---|---|---|
Ventilatory status | ● | ● | ● |
Arm function | Original score | Re-score |
---|---|---|
Can put an item such as a book onto a shelf above shoulder height | 8 | 6 |
Can lift at least one arm above the head | 7 | 5 |
Can lift at least one arm to shoulder height | 6 | |
Can eat a meal without any help | 5 | |
Needs help to cut up food but can feed and drink independently | 4 | 4 |
Needs help to drink or feed | 3 | 3 |
Can pick up objects (e.g., pen/money) | 2 | 2 |
Can move fingers (e.g., press on mobile or other electronic device) | 1 | 1 |
Cannot move fingers | 0 | 0 |
Mobility | Original score | Re-score |
---|---|---|
Walks independently outdoors for long distances (>1 km) | 8 | 5 |
Walks independently outdoors for medium distances (<1 km) | 7 | 4 |
Walks independently outdoors for short distances (e.g., to a car) | 6 | 3 |
Walks outdoors with help from a person | 5 | |
Walks indoors independently but requires a wheelchair outdoors | 4 | 2 |
Walks indoors with help from a person and requires a wheelchair outdoors | 3 | |
Uses a wheelchair indoors and outdoors | 2 | 1 |
Uses a wheelchair but unable to use it in some situations (e.g., cold weather) | 1 | 0 |
Unable to control the wheelchair without help | 0 |
아래는 팔 기능, 보행 및 자세 변환의 기능 수준과 폐 기능을 파악하는 설문입니다. 활동은 쉬운 동작에서 어려운 동작 순으로 나열되어 있으니
팔 기능 | |
---|---|
책 등을 어깨 높이 위에 있는 선반 등에 놓을 수 있음 | ● |
한 팔 이상을 머리 위까지 들 수 있음 | ● |
한 팔 이상을 어깨 높이까지 들 수 있음 | ● |
도움 없이 음식을 먹을 수 있음 | ● |
음식을 자르는 데는 도움이 필요하나 스스로 먹고 마실 수 있음 | ● |
먹고 마시는 데 도움이 필요함 | ● |
물건을 집어 올릴 수 있음(예, 펜이나 돈) | ● |
손가락을 움직일 수 있음(예, 휴대폰이나 다른 전자기기 다루기) | ● |
손가락을 움직일 수 없음 | ● |
보행 | |
---|---|
야외에서 먼 거리 스스로 걷기(1 km 이상) | ● |
야외에서 중간 거리 스스로 걷기(1 km 미만) | ● |
야외에서 승차 등을 비롯한 짧은 거리를 스스로 걸을 수 있음(예, 차까지) | ● |
야외에서 다른 사람의 도움을 받아 걸을 수 있음 | ● |
실내에서는 스스로 걸을 수 있으나 야외에서는 휠체어가 필요함 | ● |
실내에서는 다른 사람의 도움을 받아 걸을 수 있으며 야외에서는 휠체어가 필요함 | ● |
실내와 야외에서 휠체어를 사용함 | ● |
휠체어를 사용하지만 추운 날씨를 비롯한 특정 상황에서는 제한적임 | ● |
도움 없이는 휠체어를 제어할 수 없음 | ● |
이동 | 스스로 할 수 있음 | 도움이 필요함 | 견인이 필요하거나 불가능함 |
---|---|---|---|
바닥에서 일어나기/바닥에 앉기 | ● | ● | ● |
의자에서 일어나기/의자에 앉기 | ● | ● | ● |
침대 오르내리기 | ● | ● | ● |
변기에서 일어나기/변기에 앉기 | ● | ● | ● |
계단 오르내리기 | ● | ● | ● |
호흡 보조 | 호흡 보조 장치를 사용하지 않음 | 밤에 호흡 보조 장치를 사용함 | 낮과 밤 모두 호흡 보조 장치를 사용함 |
---|---|---|---|
호흡 상태 | ● | ● | ● |