Functional and Structural Adaptations of Skeletal Muscle in Long-Term Juvenile Dermatomyositis: A Controlled Cross-Sectional Study

Juvenile Dermatomyositis: what comes next? Long-term outcomes in childhood myositis from a patient perspective

BACKGROUND

To describe long-term outcomes in JDM using patient questionnaires and link to longitudinal, prospectively collected data for each patient within the Juvenile Dermatomyositis Cohort and Biomarker Study, UK and Ireland (JDCBS) to determine outcome predictors.  METHODS: JDCBS participants aged ≥ 16y completed the SF36, HAQ and a questionnaire regarding current disease features, medications, education and employment. Data collected from the JDCBS included disease subtype, demographics, clinical and laboratory features. Intensity indices were calculated for physician VAS, modified skin DAS, CMAS and MMT8 by dividing area under the curve (AUC) from longitudinal score trajectories by duration of study follow-up (y). Relationships between questionnaire and JDCBS clinical / laboratory data were investigated fitting statistical models appropriate for cross sectional and longitudinal data.

RESULTS

Of 190 questionnaires sent, 84 (44%) were returned. Average age of respondents was 20.6 years (SD 3.9), time since diagnosis was 12.4 years (SD 5.0), age at onset was 9.2 years (SD 4.3), female to male ratio 4.25:1. Forty-nine (59%) self-reported persistently active disease, 54 (65%) were still taking immunosuppressive medication. 14/32 at school/higher education reported myositis adversely affecting academic results. 18-24 year-olds were twice as likely to be unemployed compared the UK population (OR = 0.456, 95% CI 0.24, 0.84, p = 0.001). Participants ≥ 18 years were three times as likely to be living with a parent/guardian (OR = 3.39, p < 0.001). SF36 MCS and MMT8 intensity index scores were significantly correlated (ρ = 0.328, p = 0.007).

CONCLUSIONS

After 12.4 years, questionnaire responders reported self-perceived high rates of persistently active disease and medication use, reduced rates of employment and were more likely to live with a parent/guardian. Perceived persistently active muscle disease appeared to affect quality of life in these patients and was the most significant contributor to long-term outcomes. Our findings highlight the importance of including the patient perspective in the assessment of long term outcomes, so that that we can start to target initial management strategies more effectively based on a combination of clinical and patient-reported data.

Body composition in longstanding juvenile dermatomyositis; Associations with disease activity, muscle strength and cardiometabolic measures

OBJECTIVE

To (i) compare body composition parameters in patients with longstanding juvenile dermatomyositis (JDM) and controls and (ii) explore associations between body composition and disease activity/inflammation, muscle strength, health-related quality of life (HRQL) and cardiometabolic measures.

METHODS

In a cross-sectional study, we included 59 patients (median disease duration 16.7 y; median age 21.5 y) and 59 age- and sex-matched controls. Active/inactive disease were defined by the PRINTO criteria. Body composition was assessed by total body dual-energy absorptiometry (DXA), inflammation by hs-CRP and cytokines, muscle strength by manual muscle test (MMT-8), HRQL by 36-item short form survey physical component score (SF-36 PCS) and cardiometabolic function by echocardiography (systolic and diastolic function) and serum-lipids.

RESULTS

DXA analyses revealed lower appendicular lean mass index (ALMI) (reflecting limb skeletal muscle mass), higher body fat percentage (BF%) and higher android: gynoid fat ratio (A: G ratio) (reflecting central fat distribution) in patients than controls, despite similar BMI. Patients with active disease had lower ALMI and higher BF% than those with inactive disease; lower ALMI and higher BF% were associated with inflammation (elevated monocyte attractant protein-1 (MCP-1) and hs-CRP). Lower ALMI was associated with reduced muscle strength; higher BF% was associated with impaired HRQL. Central fat distribution (higher A: G ratio) was associated with impaired cardiac function and unfavorable serum-lipids.

CONCLUSION

: Despite normal BMI, patients with JDM, especially those with active disease, had unfavorable body composition, which was associated with impaired HRQL/muscle strength and cardiometabolic function. The association between central fat distribution and cardiometabolic alterations is a novel finding in JDM.

Juvenile Dermatomyositis: Advances in Pathogenesis, Assessment, and Management

BACKGROUND

Juvenile dermatomyositis is the most common inflammatory myopathy in the pediatric age group and a major cause of mortality and morbidity in individuals with childhood rheumatic diseases. Mounting evidence suggests that early diagnosis and timely aggressive treatment are associated with better outcomes.

OBJECTIVE

The purpose of this article is to provide readers with an update on the evaluation, diagnosis, and the treatment of juvenile dermatomyositis.

METHODS

A PubMed search was performed in Clinical Queries using the key term "juvenile dermatomyositis" in the search engine. The search strategy included meta-analyses, randomized controlled trials, clinical trials, observational studies, and reviews. The search was restricted to English literature. The information retrieved from the above search was used in the compilation of the present article.

RESULTS

Juvenile dermatomyositis is a chronic autoimmune inflammatory condition characterized by systemic capillary vasculopathy that primarily affects the skin and muscles with possible involvement of other organs. In 2017, the European League Against Rheumatism (EULAR) and the American College of Rheumatology (ACR) developed diagnostic criteria for juvenile idiopathic inflammatory myopathies and juvenile dermatomyositis. In the absence of muscle biopsies which are infrequently performed in children, scores (in brackets) are assigned to four variables related to muscle weakness, three variables related to skin manifestations, one variable related to other clinical manifestations, and two variables related to laboratory measurements to discriminate idiopathic inflammatory myopathies from non-idiopathic inflammatory myopathies as follows: objective symmetric weakness, usually progressive, of the proximal upper extremities (0.7); objective symmetric weakness, usually progressive, of the proximal lower extremities (0.8); neck flexors relatively weaker than neck extensors (1.9); leg proximal muscles relatively weaker than distal muscles (0.9); heliotrope rash (3.1); Gottron papules (2.1); Gottron sign (3.3); dysphagia or esophageal dysmotility (0.7); the presence of anti-Jo-1 autoantibody (3.9); and elevated serum levels of muscle enzymes (1.3). In the absence of muscle biopsy, a definite diagnosis of idiopathic inflammatory myopathy can be made if the total score is ≥7.5. Patients whose age at onset of symptoms is less than 18 years and who meet the above criteria for idiopathic inflammatory myopathy and have a heliotrope rash, Gottron papules or Gottron sign are deemed to have juvenile dermatomyositis. The mainstay of therapy at the time of diagnosis is a high-dose corticosteroid (oral or intravenous) in combination with methotrexate.

CONCLUSION

For mild to moderate active muscle disease, early aggressive treatment with high-dose oral prednisone alone or in combination with methotrexate is the cornerstone of management. Pulse intravenous methylprednisolone is often preferred to oral prednisone in more severely affected patients, patients who respond poorly to oral prednisone, and those with gastrointestinal vasculopathy. Other steroid-sparing immunosuppressive agents such as cyclosporine and cyclophosphamide are reserved for patients with contraindications or intolerance to methotrexate and for refractory cases, as the use of these agents is associated with more adverse events. Various biological agents have been used in the treatment of juvenile dermatomyositis. Data on their efficacy are limited, and their use in the treatment of juvenile dermatomyositis is considered investigational.