Damage Extent and Predictors in Adult and Juvenile Dermatomyositis and Polymyositis as Determined With the Myrositis Damage Index

Environmental Autoimmunity Group, National Institute of Environmental Health Sciences, NIH, Bethesda, MD 20892-1301, USA.
Arthritis & Rheumatology (Impact Factor: 7.76). 11/2009; 60(11):3425-35. DOI: 10.1002/art.24904
Source: PubMed


We undertook this study to validate the Myositis Damage Index (MDI) in juvenile and adult myositis, to describe the degree and types of damage and to develop predictors of damage.
Retrospective MDI evaluations and prospective assessment of disease activity and illness features were conducted. Patients with juvenile-onset disease (n = 143) were evaluated a median of 18 months after diagnosis; 135 patients were assessed 7-9 months later, and 121 were last assessed a median of 82 months after diagnosis. Ninety-six patients with adult-onset dermatomyositis or polymyositis had a baseline assessment a median of 30 months after diagnosis; 77 patients had a 6-month followup evaluation, and 55 had a final assessment a median of 60 months after diagnosis.
Damage was present in 79% of juvenile patients and in 97% of adult patients. In juveniles, scarring, contractures, persistent weakness, muscle dysfunction, and calcinosis were most frequent (23-30%) at the last evaluation. In adults, muscle atrophy, muscle dysfunction, and muscle weakness were most frequent (74-84%). MDI severity correlated with physician-assessed global damage, serum creatinine, and muscle atrophy on magnetic resonance imaging, and in juveniles also with functional disability and weakness. MDI damage scores and frequency were highest in patients with a chronic illness course and in adult patients who died. Predictors of damage included functional disability, duration of active disease, disease severity at diagnosis, physician-assessed global disease activity, and illness features, including ulcerations in children and pericarditis in adults.
Damage is common in myositis after a median duration of 5 years in patients with adult-onset disease and 6.8 years in patients with juvenile-onset disease. The MDI has good content, construct, and predictive validity in juvenile and adult myositis.

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Available from: Robert M Rennebohm, Jun 13, 2014
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    • "Calcinosis is a relatively common disease manifestation in JDM and occurs in up to 30% of cases; it is a cause of considerable morbidity, and can lead to skin ulceration, pain from nerve entrapment and joint contractures [4,6,31]. It typically occurs 1 to 3 years after JDM diagnosis, but may develop at the onset of illness or up to 20 years later [32]. "
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    ABSTRACT: Adult and juvenile dermatomyositis share the hallmark features of pathognomic skin rash and muscle inflammation, but are heterogeneous disorders with a range of additional disease features and complications. The frequency of important clinical features such as calcinosis, interstitial lung disease and malignancy varies markedly between adult and juvenile disease. These differences may reflect different disease triggers between children and adults, but whilst various viral and other environmental triggers have been implicated, results are so far conflicting. Myositis-specific autoantibodies can be detected in both adults and children with idiopathic inflammatory myopathies. They are associated with specific disease phenotypes and complications, and divide patients into clinically homogenous subgroups. Interestingly, whilst the same autoantibodies are found in both adults and children, the disease features remain different within autoantibody subgroups, particularly with regard to life-threatening disease associations, such as malignancy and rapidly progressive interstitial lung disease. Our understanding of the mechanisms that underlie these differences is limited by a lack of studies directly comparing adults and children. Dermatomyositis is an autoimmune disease, which is believed to develop as a result of an environmental trigger in a genetically predisposed individual. Age-specific host immune responses and muscle physiology may be additional complicating factors that have significant impact on disease presentation. Further study into this area may produce new insights into disease pathogenesis.
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    • "Such core outcome variables include an overall physician assessment and a parent/patient assessment by visual analogue or Likert scale, a measure of functional ability typically using the Child Health Assessment Questionnaire (CHAQ), assessment of muscle strength using CMAS or MMT8, laboratory variables (creatine kinase, lactate dehydrogenase, erythrocyte sedimentation rate) and assessment of disease activity that captures extramuscular disease (the DAS or the Myositis Disease Activity Assessment Tool, MDAAT) [Wedderburn and Rider, 2009]. The Myositis Damage Index is another potentially useful tool which has recently been validated in both adult and paediatric populations for the assessment of disease-related damage in patients with dermatomyositis [Isenberg, 2004; Rider et al. 2011]. As the collection of such data items becomes more routine in specialist centres and beyond, the comparison of outcomes between different treatment protocols and regimes, as well as in clinical trials, will become possible. "
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    • "Several studies have suggested that higher CK levels are associated with increased disease activity [11,13,28], though levels are not always reliable as predictors of disease activity or therapeutic response, despite their being used widely in clinical practice. A higher initial CK level may be associated with a more rapidly progressing course, prompting patients to seek treatment more quickly. "
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