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About the Tools

In order to determine how myositis patients' illnesses change over time, information is collected from both physicians and patients in a standardized way.

Disease activity assesses the manifestations of myositis which are thought to be reversible that result directly from the inflammatory process, whereas disease damage are those persistent changes in anatomy, physiology, pathology or function which result from previously active disease and from complications of therapy or other events.

IMACS has developed a consensus on a set of Core Set Domains and Measures for the assessment of disease activity, disease damage and patient-reported outcomes in adult and juvenile myositis patients. They are as follows:

Disease Activity Core Set Measures

  • Physician Global Activity - Visual Analogue Scale/Likert
  • Patient/Parent Global Activity - Visual Analogue Scale/Likert
  • Muscle Strength - Manual Muscle Testing (MMT)
  • Physical Function - Health Assessment Questionnaire (HAQ), Childhood Health Assessment Questionnaire (CHAQ), Childhood Myositis Assessment Scale (CMAS)
  • Laboratory - Muscle enymes
  • Extra-Muscular Activity - Myositis Disease Activity Assessment Tool (MDAAT) [MyoAct, MITAX]

Disease Damage Core Set Measures

  • Myositis Damage Index
  • Physician Global Damage - Visual Analogue Scale/Likert
  • Patient/Parent Global Damage - Visual Analogue Scale/Likert
  • Muscle Strength - MMT
  • Physical Function - [C]HAQ

Patient Reported Outcomes

  • Health Related Quality of Life using SF-36/CHQ, PedsQL
  • Myositis-specific measure to be developed/validated
  • Patient-reported fatigue measures to be developed/validated

Reference for Consensus of Core Set Domains and Measures for the assessment of disease activity, disease damage and patient-reported outcomes in adult and juvenile myositis patients


  • Miller FW, Rider LG, Chung YL, Cooper R, Danko K, Farewell V, Lundberg I, Morrison C, Oakley L, Oakley I, Pilkington C, Vencovsky J, Vincent K, Scott DL, Isenberg DA, for the International Myositis Outcome Assessment Collaborative Study Group, Proposed preliminary core set measures for disease outcome assessment in adult and juvenile idiopathic inflammatory myopathies, Rheumatology (Oxford), 2001 Nov, 40(11):1262-73. Pub Med (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11709610&dopt=Abstract) Exit NIEHS.

Restricted Tool Access

  • A portion of the IMACS tools are only available via download by registered members of IMACS. Though all users have access to all tool descriptions and references (where applicable), only registered members have access to download the tools themselves and view any educational resources associated with the tool. IMACS members can view these documents and videos by providing their Login Name and Password.

Content Types

The tools are available for download in the following media types:

  • Adobe PDF documents pdf icon
  • Microsoft Word documents word icon
  • Flash presentations flash icon

Preliminary Definitions of Improvement

  • IMACS has also developed and partially validated Preliminary Definitions of Improvement for Adult and Juvenile Myositis which combine these core set measures of disease activity and define clinically meaningful change in each of the core set activity measures. IMACS suggests that these 13 Preliminary Definitions of Improvement be used as outcome measures or endpoints for all therapeutic trials in adult and juvenile myositis.

    Rider LG, Giannini EH, Brunner HI, Ruperto N, James-Newton L, Reed AM, Lachenbruch PA, Miller FW; International Myositis Assessment and Clinical Studies Group , International Consensus On Preliminary Definitions of Improvement for Adult and Juvenile Myositis, Arthritis Rheum., 2004 Jul, 50(7):2281-90
    Pub Med (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15248228) Exit NIEHS
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Last Reviewed: October 30, 2007