Childhood Myositis Assessment Scale Score Research Articles

P.042 Anti-HMG Coenzyme A reductase antibody (anti-HMGCR) myopathy: case review of two pediatric patients from a single center

Background: Necrotizing anti-HMGCR myopathy is rare in children. Pediatric cases are not typically associated with statin use or malignancy. Methods: Retrospective chart review (January 2009 to December 2023) identified cases of anti-HMGCR myopathy at our hospital. Results: Two patients were identified. Patient A, presented at 8 yo with a 2 year history of proximal muscle weakness. His CK was 4,840 U/L (normal <205 U/L) with a high anti-HMGCR antibody titre. His Childhood Myositis Assessment Scale (CMAS) score was 33/52. Monthly IVIG was started and his muscle strength and CK improved. Two years later, weekly methotrexate was started for persistent mild CK elevation (602 to 869 U/L). At 11 years old, 3 years after diagnosis, his CMAS score was 47 and he could participate in soccer with mild fatigue. Patient B, presented at 8 yo with acute proximal weakness, rash and CMAS 13/52. His CK was 20,185 U/L with elevated anti-HMGCR antibody titre. He received oral corticosteroids, weekly methotrexate and monthly IVIG. At 10 yo, 2 years after diagnosis, he is asymptomatic with CMAS 51. He is maintained on methotrexate monotherapy. Conclusions: Anti-HMGCR antibody myopathy requires prompt diagnosis to obviate muscle necrosis and long-term complications. Our patients showed clinical and CMAS improvement with treatment.

48 Juvenile dermatomyositis: the experience of Military Pediatrics Department of Tunis

BackgroundJuvenile dermatomyositis (JD) is a rare autoimmune disorder characterized by a non-infectious inflammatory state affecting of the muscles and skin associated with a vasculopathy which represents the essential of its physiopathogenesis.ObjectivesTo review the clinical and biological diagnosis of DMJ as well as its evolution under treatment based on the cases of two patients at the Military Pediatrics Department of Tunis.ObservationsCase 1: This was a three-and-a-half-year-old child with a history of a simple febrile seizure, admitted for a skin rash and myalgia that had been evolving for eight months. Skin examination revealed an erythematous rash of the face and upper eyelids with erythematous papular lesions in front of the proximal interphalangeal joint recalling Gottron's papules. Muscle testing was in favor of a proximal deficiency and the electromyogram (EMG) revealed a diffuse myogenic process more pronounced on the proximal muscles without signs of myositic activity. Biology analysis did not reveal a biological inflammatory syndrome but rather increased muscle enzymes levels up to 3- and 4-times normal values. On the immune status report, there was no evidence of DMJ-specific autoantibodies (ASM), but the anti-SRP antibodies associated with myositis were present. The diagnosis of DMJ was established in view of the association of typical cutaneous signs and 3 muscular signs (proximal deficit, elevation of muscle enzymes, myogenic tracing) and an evaluation of the activity of the disease according to a standardized scale by the Childhood Myositis Assessment Scale (CMAS) was required (which was at 7/52). Treatment with corticosteroids and methotrexate was started after a pretherapeutic evaluation and regular check-ups of the child showed a clear improvement of clinical and muscular signs (CMAS became at 41/52). Case 2: A 7-year-old boy, with no previous pathological history, admitted to our department to explore his gait disorder associated to erythematosquamous lesions. At the dermatological inspection, a localized erythema was noted on the upper eyelids, the nose, the cheeks and the chin area, as well as erythematosquamous lesions on the interphalangeal joints, metacarpophalangeal joints, elbows and knees (Gottron papules). The gait was waddling, the EMG was in favor of myogenic disorder and the muscular testing revealed a proximal muscular affection. The biology results showed an elevation of CPK and LDH to 1.5 times the normal values and a sedimentation rate at 40 mm/h. The antibodies determination showed the existence of anti-NXP2 antibodies specific to myositis. The progression under treatment (corticosteroids, methotrexate and adjuvant treatment) was favorable with a CMAS score of 39 (CMAS was 11 when admitted). The persistence of squamous lesions recalling calcinosis on the dorsal surfaces of the forearms was well correlated with the presence of anti-NXP2 antibodies.ConclusionThe positive diagnosis of DMJ in a child must be based on clinical and biological arguments. The immunological characterization of DMJ should be an important element in the disease management because it can explain the lesions associated with certain myositis specific antibodies as well as their evolution, which implies a particular follow-up depending on the detected antibodies (risk of cancer in anti-NXP2 AC positive patients)

P11 An unusual case of Systemic Sclerosis/JDM overlap in a child with PAX8-related congenital hypothyroidism

Introduction/BackgroundJuvenile dermatomyositis is a rare inflammatory disease with a reported incidence of 0.8–4.1 per million children per year. It presents with a constellation of symptoms and signs of inflammation of skin and muscle, and is associated with significant morbidity if untreated. Juvenile systemic sclerosis (JSSc) is an even rarer rheumatological condition of childhood with significant risk of internal organ involvement, especially cardiopulmonary disease. We herewith present the case of a 7-year-old boy with history of hypothyroidism associated with a PAX8 gene variant who presented with clinical features of an overlap of Systemic Sclerosis with JDM with supportive autoantibody profile.Description/MethodA 7-year-old boy presented with a history of restricted range of movements in his hands – noted due to difficulties with pen grip – and calcinosis. He reported symptoms of fatigue, intolerance to cold with colour changes to hands and feet, stiffness of movements particularly in the morning, and infrequent episodes of choking. His past medical history was significant for hypothyroidism secondary to a paternally inherited PAX8 missense mutation, and there is a family history of Raynaud’s and hypothyroidism. A detailed examination identified diffusely swollen hands with sclerodactyly, calcinosis of his elbows and fingertips, and limited flexion of his fingers and wrists. He also had telangiectasia of his upper eyelids, Gottron’s papules over his knees and elbows, and sluggish circulation in his hands and feet. He had evidence of mild proximal muscle weakness.His investigations revealed mild elevation of muscle enzymes with normal inflammatory markers. His autoantibody profile showed a moderately positive ANA titre of 1600 with a nucleolar pattern, and was positive for anti-NXP2 and anti-SCL-100 antibodies MRI scan of the pelvis showed no evidence of myositis, echocardiogram was normal and a high-resolution CT scan of chest was normal with no features of interstitial lung disease.The overall picture was one of Systemic Sclerosis/JDM overlap with CREST syndrome. He was commenced on induction therapy with IV Methylprednisolone and Cyclophosphamide in view of the calcinosis. After three cycles of Cyclophosphamide and weaning course of oral corticosteroids, his energy levels are significantly improved and he has better overall mobility with no significant proximal muscle weakness (Childhood Myositis Assessment Scale score 49/53). However, flexion of his fingers remains limited albeit better; he has ongoing fingertip calcinosis but fewer lesions over his elbows. He has been commenced on weekly subcutaneous Methotrexate as he completes Cyclophosphamide.Discussion/ResultsThis patient had an unusual medical history of early onset thyroid dysfunction, the genetic testing for which revealed a missense PAX8 gene variant [c.49G>Ap.(Gly17Arg)] (also present in his father, who is euthyroid). This was classified as being of uncertain significance, although felt to clinically be the most likely cause for his hypothyroidism. There was no evidence to suggest that PAX8 gene mutations increased the risk of autoimmune conditions. There is evidence that PAX8 gene mutations, when expressed on malignant cells, may confer resistance to chemotherapy, which made us rethink the plan to commence him on Cyclophosphamide. However, we were reassured that in constitutional variants, there is no increased risk of cancer, and no known history of resistance to Cyclophosphamide.This patient also demonstrated an interesting antibody pattern, as he was positive for anti-NXP2 antibodies (indicating high risk for calcinosis) and anti-SCL-100 antibodies, which are associated with a clinical subset of patients with overlap of Systemic Sclerosis and JDM and associated with extensive extra-muscular features. He had two distinct clinical phenotypes of calcinosis, which is probably explained by the presence of two autoantibodies that increase the risk of calcinosis.Key learning points/ConclusionAlthough JDM has bimodal age group for presentation in childhood, only 3% of systemic sclerosis are seen in childhood, which makes this an extremely unusual presentation, given the age, gender and the overlap features (clinical and immunological).We explored whether this rare presentation could be linked to the underlying PAX8 gene mutations, but we could not find any association.With the clinical diagnosis of systemic sclerosis, it was important to rule out cardiopulmonary complications.The other consideration was regarding the choice of therapeutic agent - whether the germline PAX8 gene variants could increase the risk of malignancies or cause resistance to chemotherapeutic agents like Cyclophosphamide, for neither of which we could find any evidence.Extensive calcinosis cutis in this patient could be explained by the presence of two risk factors (CREST syndrome and JDM with NXP2 antibodies).

Short-term effectiveness of baricitinib in children with refractory and/or severe juvenile dermatomyositis.

ObjectiveTo determine the short-term effectiveness safety of baricitinib in children with refractory and/or severe juvenile dermatomyositis (rsJDM) in a real-world setting.MethodsThis was a single-center retrospective study, including 20 children with rsJDM. They were all treated using baricitinib combined with steroids and other immunosuppressive agents. The childhood myositis assessment scale (CMAS) and PRINTO remission criteria were used to evaluate the disease severity and treatment outcome at 0, 4, 12, and 24 weeks after initiation of baricitinib.ResultsThe skin rash improved in 95% of patients (19/20) at week 24, with a significant decrease of skin-DAS at weeks 12 (6.0 vs. 2.0, p < 0.05] and week 24 [6.0 vs. 1.0, p < 0.05) by median statistics. The CMAS score increased significantly at week 12 (41.0 [29.0, 44.0] vs. 46.0 [42.0, 52.0], p < 0.05) and week 24 (41.0 [29.0, 44.0] vs. 50.0 [45.0, 52.0], p < 0.05), as did the manual muscle testing (MMT)-8 score at week 24 (73.0 [610, 76.0] vs. 79.0 [77.0, 80.0], p < 0.05). At 24 weeks, the complete response (CR) and partial response (PR) were achieved in 75% (15/20) and 15% (3/20), respectively. The dose of corticosteroids (CS) decreased by 37% from the baseline (0.53 [0.42, 1.00] mg/kg) to week 12 (0.33 [0.18, 0.40] mg/kg) (p < 0.05), and by 49% at week 24 (p < 0.05). No serious side effects were observed.ConclusionBaricitinib combined with traditional immunosuppressants treatment was efficacious in rsJDM. Add-on therapy of baricitinib was helpful for tapering CS dose. No serious side effects were observed in this study.

Expression of myxovirus-resistance protein A: a possible marker of muscle disease activity and autoantibody specificities in juvenile dermatomyositis.

AimsTo evaluate the relationship between expression of myxovirus‐resistance protein A (MxA) protein on muscle biopsies by immunohistochemistry and disease activity in juvenile dermatomyositis (JDM) patients. Also, another aim was to investigate whether the expression of MxA is related with myositis‐specific autoantibodies (MSA) status in JDM patients.Methods103 patients (median aged 6.3, interquartile range 0.5–15.9) enrolled in the Juvenile Dermatomyositis Cohort and Biomarker Study (JDCBS). Muscle biopsies were stained with MxA and scored. Clinical data at initial presentation were collected and autoantibodies were analysed. Multiple linear regression analysis was performed to estimate the association between MxA expression on muscle fibres and muscle disease activity, and MSA status.ResultsExpression of MxA protein on JDM samples was identified in 61.2%. There was a significant association between MxA scores and Childhood Myositis Assessment Scale (CMAS) (P = 0.002), and Manual Muscle Testing of Eight Muscles (MMT8) (P = 0.026). CMAS and MMT8 scores were significantly lower in the group of patients with strong MxA expression. MxA scores differed according to MSA subgroups (P = 0.002). Patients with positive nuclear matrix protein 2 autoantibodies had strong MxA expression, whereas anti‐melanoma differentiation‐associated gene 5 positive patients had no or weak MxA expression.ConclusionsThis study reveals the significant association between level of MxA expression on muscle fibres and clinical measures of muscular disease activity in JDM patients and MSA status. This confirms type I interferonopathies in muscle fibres of JDM patients which could help with improving treatment outcome in JDM patients and underscoring the distinct pathophysiological pathways in different MSA status.

Analysis of Published Criteria for Clinically Inactive Disease in a Large Juvenile Dermatomyositis Cohort Shows That Skin Disease Is Underestimated.

ObjectiveThe Pediatric Rheumatology International Trials Organisation (PRINTO) recently published criteria for classification of patients with juvenile dermatomyositis (DM) as having clinically inactive disease. The criteria require that at least 3 of 4 conditions be met, i.e., creatine kinase level ≤150 units/liter, Childhood Myositis Assessment Scale score ≥48, Manual Muscle Testing in 8 muscles score ≥78, and physician's global assessment of overall disease activity (PGA) ≤0.2. The present study was undertaken to test these criteria in a UK cohort of patients with juvenile DM.MethodsWe assessed 1,114 patient visits for the 4 items in the PRINTO criteria for clinically inactive disease. Each visit was analyzed to determine whether skin disease was present. The Disease Activity Score (DAS) for juvenile DM was determined in 59 patients.ResultsAt 307 of the 1,114 visits, clinically inactive disease was achieved based on the 3 muscle criteria (but with a PGA of >0.2); rash was present at 65.8% of these visits and nailfold capillary abnormalities at 35.2%. When PGA ≤0.2 was one of the 3 criteria that were met, the frequency of skin signs was significantly lower (rash in 23.1% and nailfold capillary abnormalities in 8.7%). If PGA was considered an essential criterion for clinically inactive disease (P‐CID), patients with active skin disease were less likely to be categorized as having clinically inactive disease (a median DAS skin score of 0 [of a possible maximum of 9] in visits where the PGA was ≤0.2, versus a median DAS skin score of 4 in patients meeting the 3 muscle criteria [with a PGA of >0.2]; P < 0.001). Use of the P‐CID led to improvements in the positive predictive value and the positive likelihood ratio (85.4% and 11.0, respectively, compared to 72.9% and 5.1 with the current criteria).ConclusionThere was a high frequency of skin disease among patients with juvenile DM who did not meet the PGA criterion for inactive disease but met the other 3 criteria. Incorporating PGA as an essential criterion for clinically inactive disease helps prevent the misclassification of patients with active skin disease.

G380(P) The Role of Etanercept in Juvenile Dermatomyositis (JDMS) in Children

IntroductionJuvenile dermatomyositis is a rare autoimmune disease characterised by profound muscle weakness in addition to skin lesions, calcinosis, and underlying vasculopathy. Current treatment plans, including methotrexate and corticosteroids, are ineffective...

Clinical Characteristics of Children With Juvenile Dermatomyositis: The Childhood Arthritis and Rheumatology Research Alliance Registry

To investigate aspects of juvenile dermatomyositis (DM), including disease characteristics and treatment, through a national multicenter registry. Subjects meeting the modified Bohan and Peter criteria for definite juvenile DM were analyzed from the cross-sectional Childhood Arthritis and Rheumatology Research Alliance (CARRA) Registry between 2010 and 2012 from 55 US pediatric rheumatology centers. Demographics, disease characteristics, diagnostic assessments, and medication exposure data were collected at enrollment. A total of 384 subjects met the criteria for analysis. At enrollment, the median Childhood Myositis Assessment Scale score was 51 (interquartile range [IQR] 46-52), the median Childhood Health Assessment Questionnaire score was 0 (IQR 0-0.5), and the median physician and subject global assessment scores were 1 (IQR 0-2) and 1 (IQR 0-3), respectively, out of a maximum of 10. Of the diagnostic assessments, magnetic resonance imaging was more likely than electromyography or muscle biopsy to show abnormalities. A total of 329 subjects had ≥2 diagnostic studies performed, and >34% of these subjects reported ≥1 negative study. Ninety-five percent had been treated with corticosteroids and 92% with methotrexate, suggesting that these medications were almost universally prescribed for juvenile DM in the US. In 2 years, the ongoing CARRA Registry has collected clinical data on 384 children with juvenile DM and has the potential to become one of the largest juvenile DM cohorts in the world. More research is needed about prognostic factors in juvenile DM, and differences in therapy based on manifestations of disease need to be explored by practitioners. This registry provides the infrastructure needed to advance clinical and translational research and represents a major step toward improving outcomes of children with juvenile DM.

Lack of Achievement of a Full Score on the Childhood Myositis Assessment Scale by Healthy Four‐Year‐Olds and Those Recovering From Juvenile Dermatomyositis

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

Pulmonary Function Tests in Idiopathic Inflammatory Myopathy: Association With Clinical Parameters in Children

To determine the association of decreased lung function in children with idiopathic inflammatory myopathies (IIMs) with specific clinical parameters. This study of 38 children ages 6-23 years diagnosed with definite/probable IIM evaluated the association of myositis-specific/-associated antibodies (MSAs/MAAs), duration of untreated disease at diagnosis, Disease Activity Score for muscle (DAS-M), muscle-derived enzymes (aldolase, lactate dehydrogenase [LDH], aspartate transaminase, and creatine phosphokinase [CPK]), neopterin and von Willebrand factor antigen, and the Childhood Myositis Assessment Scale (CMAS) scores with data from pulmonary function testing (PFT). Impaired PFTs were defined as total lung capacity (TLC) or diffusing capacity for carbon monoxide (DLCO) of <80% predicted. The PFTs documented that 37% of the children (14 of 38) had either decreased TLC or decreased DLCO; 5% (2 of 38) had both. Children with decreased TLC alone (7 [18%] of 38) were older both at the time of PFT and diagnosis, had anti-Jo-1 and anti-Scl-70 antibody, and had elevated levels of CPK and neopterin. Children with decreased DLCO alone (5 [13%] of 38) had a shorter duration of untreated disease at diagnosis, had higher DAS-M and total DAS, were positive for anti-Ro and anti-PL-12, had increased LDH, and had elevated levels of neopterin and aldolase, with low CMAS scores for items 1, 3, 10, 11, and 14. Assessment of PFTs in children with IIMs should be considered, since more than one-third of patients were found to be impaired. The presence of MSAs/MAAs, an elevated serum neopterin level (mean ± SD 12.4 ± 9.6 nmoles/liter, normal value <10.5), older age at diagnosis, and shorter duration of untreated disease at diagnosis suggest the presence of potential lung pathology.

Use of the childhood myositis assessment scale to measure disease activity in juvenile dermatomyositis and the possible limitation of patient age

Aims We aimed to assess the use of the Childhood Myositis Assessment Scale (CMAS) via a retrospective audit in our tertiary rheumatology department. CMAS, our audit gold standard, is internationally validated, included in two recently proposed sets of measures of disease activity in Juvenile Dermatomyositis (JDM). Methods Physiotherapy and medical notes of all patients diagnosed with JDM from 2005 to 2011 were reviewed recording CMAS scores and other JDM assessment tools including muscle-enzymes and Childhood Health Assessment Questionnaires (CHAQ). Results Eleven new patients were diagnosed, in-keeping with the incidence of JDM (age range 3-15 years). Most CMAS scores were done by our physiotherapist. All had a CMAS prior to treatment, 73% on the day of diagnosis and all within 2 days of diagnosis. The five younger children (≤5 years) had higher CMAS scores at diagnosis (mean 29) than the six older children (mean 22). Muscle-enzyme results were documented at diagnosis for all (maximum Creatinine Kinase 18100 U/l). All patients had follow-up CMAS. Children living further from the tertiary hospital had less CMAS scores documented (table 1). Younger children rarely achieved a maximum CMAS score at follow-up (table 2). 9/11 patients had CHAQ data in their notes (scores: 0-1.625) although unexpectedly not dated. Conclusions This audit confirms that from 2005-2011 our department routinely used CMAS for all JDM patients at diagnosis and follow-up. This involved an important physiotherapist role. The lower number of CMAS scores documented for children living >50 miles away was probably because there were also some done at local hospitals unavailable for this audit. Persistent low scores at follow up for our younger patients may reflect a recently reported finding that ≤5 year olds without JDM are unable to score a maximum CMAS score. We propose a novel CMAS computer game for young JDM patients. CMAS, CHAQ, and muscle-enzymes are now included on a database at each clinic visit and re-audit will be performed in the future.

Long‐term muscular outcome and predisposing and prognostic factors in juvenile dermatomyositis: A case–control study

To compare muscle strength, physical health, and HLA-DRB1 allele carriage frequencies in patients with longstanding juvenile dermatomyositis (DM) with that of controls, and to determine the presence of and risk factors for muscle weakness and magnetic resonance imaging (MRI)-detected muscle damage in juvenile DM patients. Fifty-nine patients with juvenile DM examined a median of 16.8 years (range 2.0-38.1 years) after disease onset were compared with 59 age- and sex-matched controls. Muscle strength/endurance was measured by manual muscle testing (MMT) and the Childhood Myositis Assessment Scale (CMAS); health status was measured by the Short Form 36. HLA-DRB1 alleles were determined by sequencing in patients and 898 healthy controls. In patients, disease activity/damage was measured by the Disease Activity Score (DAS), Myositis Damage Index (MDI), Health Assessment Questionnaire/Childhood Health Assessment Questionnaire, and MRI scans of the thigh muscles. Early disease characteristics were obtained by chart review. Patients had lower muscle strength/endurance (P < 0.001 for both) and physical health (P = 0.014) and increased HLA-DRB1*0301 (P = 0.01) and DRB1*1401 (P = 0.003) compared with controls. In patients, persistent muscle weakness was found in 42% with MMT (score <78) and in 31% with the CMAS (score <48), whereas MRI-detected muscle damage was found in 52%. Muscle weakness and MRI-detected muscle damage were predicted by MDI muscle damage and a high DAS 1 year postdiagnosis. A median of 16.8 years after disease onset, juvenile DM patients were weaker than the controls; muscle weakness/reduced endurance was found in 31-42% of patients and MRI-detected muscular damage was found in 52% of patients. The outcomes were predicted by high disease activity and muscle damage present 1 year postdiagnosis.

Normal scores for nine maneuvers of the Childhood Myositis Assessment Scale.

To document and evaluate the scores that normal, healthy children achieve when performing 9 maneuvers of the Childhood Myositis Assessment Scale (CMAS). A total of 303 healthy children, 4-9 years of age, were scored as they performed 9 CMAS maneuvers. The data were then evaluated to determine whether normal scores for some maneuvers are age and sex dependent. All children were able to achieve maximum possible scores for the supine to prone, supine to sit, floor sit, floor rise, and chair rise maneuvers. All but 2 4-year-olds achieved a maximum possible score for the arm raise/duration maneuver. Performance of the head lift and sit-up maneuvers varied significantly, depending primarily on age. Children in all age groups had less difficulty performing the leg lift than the head lift or sit-up. The normative data generated by this study are of value for interpreting the serial CMAS scores of children with idiopathic inflammatory myopathies.

Validation and clinical significance of the Childhood Myositis Assessment Scale for assessment of muscle function in the juvenile idiopathic inflammatory myopathies.

To examine the measurement characteristics of the Childhood Myositis Assessment Scale (CMAS) in children with juvenile idiopathic inflammatory myopathy (juvenile IIM), and to obtain preliminary data on the clinical significance of CMAS scores. One hundred eight children with juvenile IIM were evaluated on 2 occasions, 7-9 months apart, using various measures of physical function, strength, and disease activity. Interrater reliability, construct validity, and responsiveness of the CMAS were examined. The minimum clinically important difference (MID) and CMAS scores corresponding to various degrees of physical disability were estimated. The intraclass correlation coefficient for 26 patients assessed by 2 examiners was 0.89, indicating very good interrater reliability. The CMAS score correlated highly with the Childhood Health Assessment Questionnaire (C-HAQ) score and with findings on manual muscle testing (MMT) (r(s) = -0.73 and 0.73, respectively) and moderately with physician-assessed global disease activity and skin activity, parent-assessed global disease severity, and muscle magnetic resonance imaging (r(s) = -0.44 to -0.61), thereby demonstrating good construct validity. The standardized response mean was 0.81 (95% confidence interval 0.53, 1.09) in patients with at least 0.8 cm improvement on a 10-cm visual analog scale for physician-assessed global disease activity, indicating strong responsiveness. In bivariate regression models predicting physician-assessed global disease activity, MMT remained significant in models containing the CMAS (P = 0.03) while the C-HAQ did not (P = 0.4). Estimates of the MID ranged from 1.5 to 3.0 points on a 0-52-point scale. CMAS scores corresponding to no, mild, mild-to-moderate, and moderate physical disability, respectively, were 48, 45, 39, and 30. The CMAS exhibits good reliability, construct validity, and responsiveness, and is therefore a valid instrument for the assessment of physical function, muscle strength, and endurance in children with juvenile IIM. Preliminary data on MID and corresponding levels of disability should aid in the clinical interpretation of CMAS scores when assessing patients with juvenile IIM.

Decreased aerobic capacity in children with juvenile dermatomyositis

To determine whether patients with juvenile dermatomyositis (DM) have limited aerobic capacity compared with healthy controls. Fourteen juvenile DM patients with inactive to moderately active, stable disease (age range 7-17 years) and 14 age- and sex-matched controls performed a maximal exercise test using a cycle ergometer. Oxygen uptake and power were measured at peak exercise (VO(2peak) and W(peak), respectively) and at anaerobic threshold (AT and W(AT)). Juvenile DM disease activity and damage were also assessed. Patients with juvenile DM had significantly reduced VO(2peak) (19.6 ml O(2)/kg/minute in juvenile DM versus 31.1 ml O(2)/kg/minute in controls), peak heart rate (166 versus 184 beats per minute), W(peak) (1.6 versus 2.7 watts/kg), AT (11.1 versus 18.0 ml O(2)/kg/minute) and W(AT) (0.6 versus 1.4 watts/kg), compared to controls (P <or= 0.05 for each). Aerobic exercise parameters correlated with physician global disease activity and damage, T1-weighted magnetic resonance imaging, and Childhood Myositis Assessment Scale scores (r(s) = 0.58 - 0.82, P <or= 0.05). Patients with juvenile DM with a range of disease activity have a decreased aerobic and work capacity compared to healthy children. Aerobic exercise limitation in juvenile DM correlates best with measures of disease damage (global damage assessment, T1-weighted magnetic resonance imaging, and disease duration). Aerobic exercise testing may be valuable in the assessment of physical endurance, and aerobic training may be indicated as part of the therapeutic regimen in myositis patients with inactive to moderately active, stable disease.

Development of validated disease activity and damage indices for the juvenile idiopathic inflammatory myopathies. II. The Childhood Myositis Assessment Scale (CMAS): a quantitative tool for the evaluation of muscle function. The Juvenile Dermatomyositis Disease Activity Collaborative Study Group.

To develop, validate, and determine the measurement characteristics of a quantitative tool for assessing the severity of muscle involvement in children with idiopathic inflammatory myopathies. The Childhood Myositis Assessment Scale (CMAS) was developed from 2 existing observational functional assessment tools to assess muscle function in the areas of strength and endurance across a wide range of ability and ages. The 14 ordinal items included were chosen to assess primarily axial and proximal muscle groups and are ranked with standard performance and scoring methods. Following the development of the CMAS, a training video and written instructions were developed and reviewed by the physicians participating in this study. Subsequently, utilizing a randomized block design, 12 physicians independently scored 10 children (9 with dermatomyositis, 1 with polymyositis; ages 4-15 years) twice in one day (morning and afternoon) on the CMAS. A pediatric physical therapist performed quantitative manual muscle strength testing (MMT) twice on each child (morning and afternoon), including the neck, trunk, and proximal and distal extremity muscle groups. The CMAS has a potential range of 0-51, with higher scores indicating greater muscle strength and endurance. The observed mean for the 10 patients was 36.4 (median 44, SD 14.1, observed range 5-51). The total score for the CMAS correlated with the physician's global assessment (by visual analog scale) of disease activity, the MMT score, serum creatine kinase level, and the Juvenile Arthritis Functional Assessment Report score. The score on the CMAS was not correlated with patient age. Interrater reliability (Kendall's coefficient of concordance) ranged from 0.77 to 1.0 for individual items (all P < 0.001), and overall, it was 0.95 (P < 0.001). Intrarater reliability for the individual physicians was measured by correlation of the CMAS scores for each patient on 2 separate evaluations and ranged from 0.97 to 0.99, with an overall correlation for all physicians of 0.98 (all P < 0.001). The CMAS demonstrated an acceptable range of observed scores, excellent convergent validity, and excellent inter- and intrarater reliability. The CMAS is validated to quantitatively assess muscle function in the areas of strength and endurance in children with idiopathic inflammatory myopathies. It can be used in routine clinical care as well as therapeutic trials.