Juvenile Autoimmune Necrotizing Myopathies

Study Overview
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Brief Summary
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Autoimmune necrotizing myopathies (AINM) in adult patients are characterized by severity of muscle damage, presence of necrosis with little inflammation on muscle biopsy and anti-HMGCR or anti-SRP auto-antibodies. Data on AINM in children are currently lacking. The purpose of this study is to specify the characteristics at AINM diagnosis, treatments and evolution of juvenile AINM with anti-HMGCR or anti-SRP antibodies.

Official Title
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Clinical, Paraclinical, Functional Characteristics and Evolution of Juvenile Autoimmune Necrotizing Myopathies in a National Retrospective Cohort

Conditions
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Immune-Mediated Necrotizing Myopathy

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: AINM histologically proved by predominant muscle fibers necrosis lesions associated with minimal or absent inflammatory lesions Either anti-SRP or anti-HMGCR antibodies positivity Disease onset before age 18 Exclusion Criteria: Seronegative necrotizing myopathies Forms compatible with another type of myositis (e.g. dermatomyositis)
Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| autoimmune necrotizing myopathy beginning before 18<br> | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Type of muscle involvment | Proximal or distal or axial muscle involvement by muscle testing | At diagnosis | 
| Type of cutaneous involvment | Rash or Gottron lesions | At diagnosis | 
| Other clinical manifestations | Dysphagia or dyspnea or fever or interstitial lung involvement or articular involvement or gastrointestinal involvment | At diagnosis | 
| Blood CK level | Blood CK level | At diagnosis | 
| Histology | Results of muscle biopsy : necrosis | At diagnosis | 
| Histology | Results of muscle biopsy : inflammation | At diagnosis | 
| MMT score | MMT score | At diagnosis | 
| CMAS score | CMAS score | At diagnosis | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Type of drugs used | Drugs ever used : name and duration | At last visit | 
| Iatrogenic complications | Infectious complications | At last visit | 
| Iatrogenic complications | Bone complications | At last visit | 
| Status of the disease at last visit | Status of the disease at last visit : active or remission or death | At last visit | 
| Number of relapses | Number of relapses | At last visit | 
| Type of muscle involvment | Proximal or distal or axial muscle involvement by muscle testing | At last visit | 
| Type of cutaneous involvment | Rash or Gottron lesions | At last visit | 
| Other clinical manifestations | Dysphagia or dyspnea or fever or interstitial lung involvement or articular involvement or gastrointestinal involvment | At last visit | 
| Blood CK level | Blood CK level | At last visit | 
| CMAS score | CMAS score | At last visit | 
| MMT score | MMT score | At last visit | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Autoimmune necrotizing myopathy, anti-HMGCR antibodies, anti-SRP antibodies