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Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Subjects and methods
  5. Results
  6. Discussion
  7. AUTHOR CONTRIBUTIONS
  8. REFERENCES

Objective

To test 4-year-olds, using 14 maneuvers of the Childhood Myositis Assessment Scale (CMAS), comparing healthy children with those with juvenile dermatomyositis (DM).

Methods

Healthy 4-year-olds (n = 28) completed the CMAS. Their scores were compared with children with juvenile DM (n = 18) who had a muscle Disease Activity Score (DAS-M) of 0.

Results

The healthy children achieved a mean ± SD CMAS score of 46.6 ± 2.3 (interquartile range 46–47). There were no significant differences between boys and girls, and the scores were not significantly associated with height or weight. The greatest variation involved items that assessed endurance. Item 1, neck raise, yielded a mean ± SD score of 28.2 ± 19.3 seconds, with a mean ± SD CMAS score of 2.5 ± 0.9 (maximum score 5). Item 3, leg lift, yielded a mean ± SD score of 55.5 ± 37.3 seconds, with a mean ± SD CMAS score of 3.1 ± 1.1 (maximum score 5). Item 5, sit-ups maneuver, yielded a mean ± SD score of 5.3 ± 1.1 sit-ups. Almost identical data were obtained for the 18 treated children with juvenile DM who had normal strength on the DAS-M.

Conclusion

Healthy children ages 4 years do not achieve the total CMAS score of 52 attained by older children. Both boys and girls were remarkably consistent, with a mean CMAS score of 46.6. Children ages 4 years with juvenile DM with a DAS-M of 0 also achieved a CMAS score of 46.6. We conclude that half of 4-year-old children achieve a mean CMAS score of 46 or 47, not a total CMAS score of 52, suggesting that weakness may be overdiagnosed in 4-year-olds with an inflammatory myopathy.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Subjects and methods
  5. Results
  6. Discussion
  7. AUTHOR CONTRIBUTIONS
  8. REFERENCES

Juvenile dermatomyositis (DM) is characterized clinically by progressive proximal muscle weakness and a distinctive rash over the face and extremities, and in severe cases, the trunk ([1]). The mean age at onset of symptoms is 6.7 years, but more than 25% of children have their first symptom at age ≤4 years ([2]). To clinically assess muscle strength and function, a range of measures are often utilized, including manual muscle strength testing (MMT) and the Childhood Health Assessment Questionnaire (C-HAQ). MMT has good inter-/intrarater reliability and is sensitive to changes in strength when muscles are moderately weak, but may not be reliable in children ages <5 years ([3, 4]). The C-HAQ is highly correlated with muscle strength and overall disease activity in childhood idiopathic inflammatory myopathy (IIM), although it becomes difficult to measure improvement in status as subjects approach normal physical function and are unable to score better than zero ([5]). Due to the limitations of evaluation of physical performance that do not include endurance, such as the MMT and the C-HAQ, additional assessments such as the Childhood Myositis Assessment Scale (CMAS) were developed. The CMAS was validated and found to have clinical utility by the Juvenile Dermatomyositis Disease Activity Collaborative Study Group as a quantitative, observational, performance-based instrument to assess proximal muscle strength, function, and endurance in subjects ages 2 years to adults ([6-8]). This test is now used internationally in conjunction with other measures of strength and function ([9, 10]).

The CMAS consists of 14 physical maneuvers designed to assess proximal and axial muscle groups ([6-8]). Subjects are graded based on their ability to complete specific tasks and to achieve and maintain specific positions over a period of time for tests of endurance. The maximum score is 52 points. The primary purpose of the CMAS is to serve as a longitudinal assessment tool for an individual patient to quantitatively establish improvement or worsening since a previous examination ([3]). However, during the development of the CMAS, it was realized that not all children might be able to achieve a full point score based on typical development and ability to participate in activities. To address this, Rennebohm et al, as part of a larger study of 303 children ages 4–9 years, tested 25 healthy boys and 25 healthy girls in each age group to determine how successfully they could perform 9 CMAS maneuvers ([6]). This group found that results of the head lift, leg lift, and sit-up maneuvers revealed age-related and, to a much lesser degree, sex-related variability. Their results documented that typically developing children, particularly younger children, were not necessarily able to achieve maximum possible scores for some CMAS maneuvers ([6]).

Based on the above results for children ages 4–9 years and the current utilization of this measure for children as young as age 2 years, the present study was designed to document the scores achievable on the CMAS by healthy children ages 4.0–4.9 years. Previous research had incorporated only 9 maneuvers of the CMAS, since the additional 5 maneuvers were added after the commencement of the study ([8]). This study documented the scores for children on all 14 maneuvers of the CMAS test to provide comparative data for medical personnel when they determine whether performance on the CMAS is reflective of disease activity or age-related developmental limitations.

Box 1. Significance & Innovations

  • A group of 28 healthy children ages 4 years scored a mean of 46.6 of 52 points on the Childhood Myositis Assessment Scale (CMAS).
  • Based on the current usage of the CMAS in the clinical setting, weakness may be overdiagnosed in children ages 4 years who have developed an inflammatory myopathy.

Subjects and methods

  1. Top of page
  2. Abstract
  3. Introduction
  4. Subjects and methods
  5. Results
  6. Discussion
  7. AUTHOR CONTRIBUTIONS
  8. REFERENCES

Healthy children ages 4 years were recruited through a global e-mail sent to members of the staff of Ann & Robert H. Lurie Children's Hospital in Chicago, Illinois. Approval from the Lurie Children's Research Hospital Institutional Review Board (2010–14188) was obtained prior to recruitment. Interested parents answered prescreening questions via phone to determine the child's eligibility for the study. Written informed consent was obtained from the parents of all eligible children who participated in a single study visit. Children with juvenile DM were assessed as part of routine clinical care.

Subjects

Fourteen boys and 14 girls ages 4.0–4.9 years were enrolled in this prospective pilot study as controls. Children were eligible for inclusion in the study if they were typically developing, healthy children. Children were excluded from the study if parents reported that the child was taking prescribed medications or had any medical diagnosis requiring therapeutic services. All enrolled subjects completed the full CMAS assessment, providing a complete data set. The mean ± SD age of all subjects was 4.4 ± 0.3 years. The racial composition was 68% white and 32% nonwhite.

Juvenile DM patients

Data were obtained from our database of >500 children with IIMs. We selected all those children with juvenile DM between the ages of 4.0 and 4.9 years who had achieved a Disease Activity Score for muscle weakness (DAS-M) of 0 after medical therapy at our facility ([9, 10]). The DAS-M was evaluated by a single individual (LMP) and has been validated ([11, 12]). Eighteen children with definite juvenile DM (by Bohan and Peter criteria) ([13]) whose DAS-M had returned to 0 after initiation of medical therapy were identified and included in this study; no child in this age range was excluded. Fifteen were white and 3 were nonwhite. The mean ± SD age of the 18 juvenile DM patients (2 boys, 16 girls) at the time of the study was 4.6 ± 0.3 years. The mean ± SD age at disease onset was 3.2 ± 0.7 years, with a mean ± SD duration of untreated disease of 7.2 ± 7.0 months before their first medication was given. The mean ± SD DAS for skin at diagnosis (first visit) was 5.1 ± 2.2 and for muscle was 3.6 ± 3.2. Of this group, 2 of 17 were positive for myositis-specific autoantibody/Ro and Mi-2 at the time of the study when their DAS-M was 0 and their mean ± SD DAS for skin was 2.6 ± 2.1. At the time of the study, 17 children were still taking medication, including 14 taking oral prednisone, 5 taking hydroxychloroquine, 5 taking intravenous methylprednisolone, 1 taking intravenous immunoglobulin, and 1 taking mycophenolate.

Measures

During the study visit, height, weight, and CMAS scores were obtained for each subject.

CMAS

The CMAS was administered using an examining table, stopwatch, step stool, chair, and pen. The 14 items were tested one after the other in the order listed on the CMAS scoring sheet. Scoring was completed based on the subject's ability to meet defined criteria, as listed in the “Standardized Method for Performing the Childhood Myositis Assessment Scale” ([8]). For all healthy controls, measurements were performed by a single individual, a clinical research nurse trained in the administration of the CMAS (RF), at the time of the study visit. The CMAS was performed for children with juvenile DM by a trained physical therapist (RQ) in the Juvenile Myositis Clinic at Northwestern University at each clinic visit, and the data were entered into the database.

DAS

The DAS-M is a validated assessment that includes scoring for pediatric muscle strength to reach a maximal score of 11 ([9, 10]). The DAS is used internationally to assess the impact of myositis on the child's performance and his or her response to therapy ([11, 12]).

Statistical analysis

The distribution of the final CMAS score was summarized using descriptive statistics, including the mean ± SD, median, minimum, and maximum, and by sex. Correlation between the CMAS score and other variables, including height and weight, was calculated using Spearman's rank correlation coefficient (ρ) for boys and girls. Comparison of CMAS scores between sexes or disease status was performed using the Wilcoxon-Mann-Whitney test.

Results

  1. Top of page
  2. Abstract
  3. Introduction
  4. Subjects and methods
  5. Results
  6. Discussion
  7. AUTHOR CONTRIBUTIONS
  8. REFERENCES

The test population of 28 healthy children achieved a total mean CMAS score of 46.6. There were no significant differences between boys and girls (mean ± SD CMAS score 46.6 ± 2.6 versus 46.6 ± 2.0; P = 0.83), and their scores were not significantly associated with their height (ρ = 0.27, P = 0.15), weight (ρ = 0.25, P = 0.20), or age (when comparing 4.0–4.5-year-olds to 4.5–4.9-year-olds; P = 0.85). We observed no significant difference (Table 1) in the mean ± SD total CMAS score between children with juvenile DM (46.1 ± 2.5) compared to healthy children (46.6 ± 2.3; P = 0.49) or between the female children with juvenile DM (46.2 ± 2.4) versus the healthy female children (46.6 ± 2.0; P = 0.86). When all children, i.e., those who were healthy and those with juvenile DM, were combined to increase the statistical power, a significant correlation was observed between CMAS score and height (ρ = 0.31, P = 0.03), and a marginally significant correlation was observed between CMAS score and weight (ρ = 0.26, P = 0.08). On item 8, arm raise score, 41 of 44 children scored 60 seconds, and the additional 3 children scored 36, 40, and 45 seconds, demonstrating very little variation overall. The greatest variation in the scores involved the additional measures that assessed endurance. Item 1, neck raise score, yielded a mean ± SD of 28.2 ± 19.3 seconds, with a mean ± SD CMAS score of 2.5 ± 0.9 (maximum score 5). Item 3, leg lift score, yielded a mean ± SD of 55.5 ± 37.3 seconds, with a mean ± SD CMAS score of 3.1 ± 1.1 (maximum score 5). Item 5, sit-up maneuver, yielded a mean ± SD score of 5.3 ± 1.1 completed sit-ups. Additional CMAS items were very consistent between the boys and the girls. The distribution of CMAS scores among the 28 healthy children was very symmetric, forming a classic bell-shaped curve. The interquartile range was 1 (first and third quartiles 46 and 47), with a median of 46. Nine children had a score of 46 and 7 children had a score of 47, for a total of 16 of 28 children studied scoring 46 or 47. Similar results are shown for children ages 4 years with juvenile DM who had achieved a DAS-M of 0 after medical therapy, even though they still had significant cutaneous involvement (Table 1).

Table 1. CMAS testing for the most variable items in 4-year-olds: healthy children compared with children with juvenile DM with a Disease Activity Score of 0*
 No. (%)Age at diagnosis, yearsAge at CMAS, yearsCMAS total scoreNeck raise duration, secondsaLeg lift duration, secondsbSit-ups performedc
  1. Values are the mean ± SD unless otherwise indicated. CMAS = Childhood Myositis Assessment Scale; DM = dermatomyositis; N/A = not applicable.

  2. a

    N = 3 missing.

  3. b

    N = 2 missing. P < 0.001 comparing healthy subjects with children with juvenile DM.

  4. c

    P < 0.001 comparing healthy subjects with children with juvenile DM.

Healthy children       
Sex       
Male14 (50.0)N/A4.5 ± 0.446.6 ± 2.623.9 ± 19.765.4 ± 41.45.2 ± 1.3
Female14 (50.0)N/A4.3 ± 0.346.6 ± 2.032.9 ± 18.643.8 ± 29.45.4 ± 0.9
Race       
White19 (67.9)N/A4.4 ± 0.446.7 ± 2.628.3 ± 19.865.6 ± 39.35.3 ± 1.2
Nonwhite9 (32.1)N/A4.4 ± 0.346.3 ± 1.727.8 ± 19.135.8 ± 23.05.4 ± 0.9
Total28 (100)N/A4.4 ± 0.346.6 ± 2.328.2 ± 19.355.5 ± 37.35.3 ± 1.1
Juvenile DM       
Sex       
Male2 (11.1)3.6 ± 0.44.8 ± 0.345.5 ± 3.535 ± 36.8120 ± 0.02 ± 1.4
Female16 (88.9)3.1 ± 0.74.6 ± 0.346.2 ± 2.442.6 ± 33.0102.1 ± 30.93 ± 1.7
Race       
White15 (83.3)3.1 ± 0.64.6 ± 0.346.3 ± 2.546.6 ± 33.0106.5 ± 26.13.1 ± 1.8
Nonwhite3 (16.7)3.8 ± 0.64.6 ± 0.245 ± 2.017.7 ± 15.091.7 ± 15.02 ± 1.0
Total18 (100)3.2 ± 0.74.6 ± 0.346.1 ± 2.541.8 ± 32.4104.1 ± 29.62.9 ± 1.7

In Table 1, it is seen that the children with juvenile DM achieved a better score on leg lifts than the controls (P < 0.05), but did not do as well on sit-ups (P < 0.05), reflecting an often-observed lag in recovery of core strength in children with juvenile DM.

The minimum, maximum, median, and mean ± SD CMAS scores achieved by the healthy controls for the 3 most variable CMAS items are shown in Table 2. These scores are based on the child's timed score as indicated in the CMAS scoring guide. A score of 120 seconds translates to a score of 5 for the head elevation and leg lift duration maneuvers, and 6 sits-ups are required to achieve a maximum score of 6 on the sit-up maneuver.

Table 2. CMAS maneuver scores by sex in healthy controls*
CMAS maneuver (maximum points possible)MinMaxMedianMean ± SD
  1. CMAS = Childhood Myositis Assessment Scale.

1. Head elevation ([5])    
Female2422.5 ± 0.7
Male1522.4 ± 1.2
3. Straight leg lift/duration ([5])    
Female2532.9 ± 1.1
Male2543.4 ± 1.2
5. Sit-ups ([6])    
Female4665.4 ± 0.9
Male2665.2 ± 1.3

Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Subjects and methods
  5. Results
  6. Discussion
  7. AUTHOR CONTRIBUTIONS
  8. REFERENCES

In this pilot study of 28 typically developing children ages 4 years, we found that the mean score achieved on the CMAS is 46.6 of 52, or 89% of the maximum score. Scores for the head elevation, straight leg lift/duration, and sit-up maneuvers were the most variable among this age group. These findings highlight the need for further research of children of all age groups to determine when the child is capable of achieving the full CMAS score, and to establish if weakness is overdiagnosed in young children with inflammatory myopathy. Although these data were collected from a small sample and reflect only one age group, they provided valuable insight into the capabilities of young children when performing the CMAS.

Physicians routinely use the CMAS data as one part of the clinical picture in determining a child's status in the disease process, and may also modify medications based in part on this information. Therefore, it is important that in addition to viewing the CMAS as a way to monitor change serially, we are also aware of how this score may vary by age and developmental level for both healthy children and those with myositis. Gaining a better understanding of the capabilities of children to achieve specific scores on the CMAS will assist the physician in determining if lower scores are reflective of the disease process or are normal age-related variations.

To our knowledge, only Rennebohm et al compiled normal scores for children on the CMAS ([6]). Their research assessed the scores for healthy children ages 4–9 years, but incorporated only 9 of the 14 maneuvers of the CMAS. The current study assessed 4-year-olds on all 14 items of the CMAS in order to add to the documented knowledge base regarding score capabilities of healthy children. The data from the children with juvenile DM document that the DAS-M is confirmed by a CMAS score that is identical to that achieved by the healthy controls. Rennebohm et al previously noted that children with myositis and healthy volunteers may have differences in attitude and motivation, which could influence their respective performance on the CMAS. We believe that this is a valid and important point, as we routinely see that motivation of both the child and/or the parent during testing can strongly influence the performance of the child during clinic visits. Additionally, children may experience a practice or learning effect after the completion of serial CMAS testing over time. We have observed that many 3- and 4-year-olds initially perform poorly on this assessment, but quickly demonstrate significant improvements in their scores over the next few visits. It is unclear at this time if these changes are purely due to treatment interventions, or if the children are also becoming more comfortable with the activities being asked of them. It is also important to note that the tasks that show the greatest variability in this pilot study (head and leg raise duration and sit-ups) are tasks that are not routinely performed by 4-year-old children. In summary, the standard of a CMAS achievement of 52 points for children ages 4 years is not realistic and may lead to the overdiagnosis of muscle weakness. We have provided evidence that a score of 46 is attainable by both healthy children and those who have recovered from juvenile DM muscle damage.

AUTHOR CONTRIBUTIONS

  1. Top of page
  2. Abstract
  3. Introduction
  4. Subjects and methods
  5. Results
  6. Discussion
  7. AUTHOR CONTRIBUTIONS
  8. REFERENCES

All authors were involved in drafting the article or revising it critically for important intellectual content, and all authors approved the final version to be published. Dr. Pachman had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Study conception and design. Quiñones, Morgan, Amoruso, Field, Pachman.

Acquisition of data. Quiñones, Morgan, Amoruso, Field, Pachman.

Analysis and interpretation of data. Quiñones, Morgan, Field, Huang, Pachman.

REFERENCES

  1. Top of page
  2. Abstract
  3. Introduction
  4. Subjects and methods
  5. Results
  6. Discussion
  7. AUTHOR CONTRIBUTIONS
  8. REFERENCES
  • 1
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  • 2
    Pachman LM, Lipton R, Ramsey-Goldman R, Shamiyeh E, Abbott K, Mendez EP, et al.History of infection before the onset of juvenile dermatomyositis: results from the National Institute of Arthritis and Musculoskeletal and Skin Diseases Research Registry.Arthritis Rheum2005;53:16672.
  • 3
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